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Chapter 6—Scan Parameters

This chapter describes the Scan Parameters area of the Exam window andprovides detailed information about each parameter. These selections allowyou to customize your scans and processing in various ways.

6 - 2 Copyright © 2008 by Hitachi Medical Systems America, Inc. All rights reserved.

MR System Reference Manual

Scan Parameters Area

The default location of the Scan Parameters area is on the right side of theExam window, as shown in the example. The Scan Parameters area can bedisplayed on either side of the Exam window. To change the display location,refer to the “Displaying the Scan Parameters Area” section in this chapter.

This area contains two tabs:

• Basic tab—Contains the 12 default parameters and any parameters you addto the tab.

• All tab—Contains all the parameters in the Echelon MR System, including thedefault parameters listed on the Basic tab.

These tabs are described in the following sections.

Scan Parameters area

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Basic Tab

The Basic tab contains the following 12 default parameters, as shown inthe example:

• FOV

• TR

• TE

• FA

• Thickness

• Interval

• Multi slice

• Freq#

• Phase#

• NSA

• Synch. StopWatch

• Gating



This tab will also contain any parameters that you choose to add. To add aparameter to the Basic tab, follow these steps:

1. Select the All tab, as shown in the example, and scroll to the bottom of theScan Parameters area.

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2. Select the Config button. The Config Setting window will open, as shown inthe example. Parameters that are displayed with a check mark, but aregrayed-out, are the Basic tab default parameters.

3. Select each parameter that you would like to add to the Basic tab bydouble left-clicking on the parameter name or by left-clicking on the checkbox next to the parameter. A green check mark in the check box indicatesthat the parameter has been selected.

4. Left-click on the OK button to save your changes and close the ConfigSetting window.

To remove a parameter from the Basic tab, follow these steps:

1. Select the All tab and scroll to the bottom of the Scan Parameters area.

2. Select the Config button. The Config Setting window will open.

3. Double left-click on the green check mark next to each parameter you wishto remove. The check mark will be removed and the parameter will not bedisplayed on the Basic tab.

4. Left-click on the OK button to save your changes and close the ConfigSetting window.

Note:Changes made to the Basic tabapply only to the Exam windowcurrently in use.

Path:Exam window,Scan Parameters areaAll tabConfig buttonConfig Setting window



All Tab

The All tab, shown in the example, displays all of the scan parameters includingthe default parameters. Because there are so many scan parameters, not all ofthem can be displayed in the window. You can use the scroll bar to locate thedesired set of parameters or left-click on the Overview button to open theScanParameterList window, which is shown in the next section.

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Scan Parameters Area Buttons

The top of the Scan Parameters area contains the following buttons:

Overview—Opens the ScanParameterList window, as shown in the example.You can view and change the various parameters found under the All tab in thisone window, rather than scrolling through all the categories.

Reset—Resets all the parameters that you changed to the previously saveddefault values.

The buttons at the bottom of the Scan Parameters area are used during scanningand are described in the “START, STOP, and Other Buttons” section inChapter 5, “Exam Window Scanning Functions.”

Path:Exam window,Scan Parameters areaAll tabOverview buttonScanParameterListwindow



Displaying the Scan Parameters Area

The Scan Parameters area can be displayed on the right or left side of theExam window. To change the display location, follow the procedure below:

1. Select the System Settings Launcher button. From the drop-down menu,select the Window Setting function. (This selection will appear if you havecustomized the drop-down menu.)

2. Under the Exam Window tab, you can change the display location ofScan Parameters in the Select Examination Window area. Additionally,under the heading Display of Task list, you can choose Graphical or TaskName for the display of the Protocol Properties area, as shown in theexamples.

Scan Parameters area on left of Exam window, graphical display of task list selected

Note:Refer to the “Launcher Buttons”section of Chapter 3, “SystemOverview,” for a detailedexplanation of the drop-downmenu customization function forLauncher toolbar buttons.

Path:System Settings drop-downmenuWindow Setting menuoptionWindow Setting window,Exam window tab

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Scan Parameters area on right of Exam window, Task Name display of task list selected

Scan Parameters Descriptions

The scan parameters are separated into the following sets of related parameters:

Sequence—Includes parameters related to the scan to be performed, such asslice plane, sequence type, and acquisition mode.

Seq. Parameter—Includes parameters related to pulse sequences (TR, TE, andNSA) and slices (thickness, interval, and number).

Advanced—Includes parameters related to additional functions, such as phasedirection, presaturation, and bandwidth.

RADAR (RADial Acquisition Regime)—Includes parameters related to thesampling of K-space in a radial pattern.

Saturation—Includes parameters related to the suppression of specific signals,such as fat, water, and silicone.



MTC (Magnetization Transfer Contrast)—Includes parameters used to changethe contrast of images by moving magnetization from bound protons to freeprotons.

VENC (Velocity ENCoding)—Includes parameters related to the use of phaseinformation to determine the rate and direction of blood flow.

SSP (Sloped Slab Profile)—Includes parameters related to a sloped slab used tosuppress blood flow saturation in 3D MRA.

MPG (Motion Probing Gradient)—Includes parameters related to scanning withthe application of a gradient magnetic field to emphasize proton diffusion. This isused with Diffusion Weighted Imaging (DWI).

Scan Control—Includes parameters related to the timing of contrast-enhancedscans in various scan modes, such as wait times, delays, and contrast agents.

RAPID (Rapid Acquisition through a Parallel Imaging Design)—Includesparameters related to the reduction of phase encode steps, which reduces scantime.

Gating—Includes parameters used with ECG, pulse, and respiratory gatedscans.

NAVI (NAVIgator Echo)—Includes parameters related to Navigator acquisi-tions, which are used to reduce artifacts produced in a scan region, such as theheart, where breathing can change the scan position.

PAPE (PArtial Phase Encode)—Includes parameters related to PAPE, whichimproves temporal resolution while maintaining image spatial resolution.

Filter/PostProcessing—Includes parameters related to improving an image’svisual characteristics, as well as other post-processing selections.

Positioning—Includes parameters related to scan position, such as slice orderand plane order.

Others—Includes parameters for receiver coils and morning QA functions.

You can change parameter values by selecting from a drop-down list of choicesor by left-clicking on up or down arrows (to change a numerical value in a field).You can also change numerical values by highlighting the field, typing the newvalue, and then pressing the Enter key. Parameter fields that are grayed-out arenot accessible; this occurrence depends on the combination of parameters thathave been selected. The Reset button at the top of the Scan Parameters windowwill reset all parameters to their previously saved default values.

The parameters are described in the remainder of this chapter.

Definition:3D MRA refers to three-dimen-sional magnetic resonanceangiography. A slab refers to acollection of slices to be excitedwith a single excitation pulse,used in 3D acquisitions.

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Sequence

The Sequence section, found under the All tab of Scan Parameters and shownin the example, contains the following parameters:

Slice Plane—Provides the following choices for the plane of the slices, asshown in the example:

• AX—Axial

• SAG—Sagittal

• COR—Coronal

• SA—Sagittal and axial

• CA—Coronal and axial

• SC—Sagittal and coronal

• SCA—Sagittal, coronal, and axial

2D/3D—Provides the following choices for the acquisition mode, as shown inthe example:

• 2D—Two-dimensional acquisition. One slice is acquired per TR.

• 3D—Three-dimensional acquisition. In 3D acquisitions, data encoded withslice direction position information is collected, in addition to phase encodingand frequency encoding. Multiple slices of image data are reconstructed usingthe 3D Fourier conversion. 3D acquisitions can achieve images with varyingslice thicknesses.

Note:The values that can be set maybe limited by the Sequence thatis selected and related scanparameters.



Sequence—Provides options for the pulse sequence. The choices are describedbelow (a partial listing is shown in each example):

• SE (Spin Echo)—Produces images with proton density, T1, and/or T2weighting.

• IR (Inversion Recovery)—Uses a 180° inverting radio frequency (RF) pulseprior to the 90° excitation pulse to acquire images with specific suppression.

• GE (Gradient Echo)—Uses a variable flip angle to acquire images with T1 orT2* contrast. The contrast weighting is primarily determined by the flip angle.

• SARGE (Steady State Acquisition with Rewound Gradient Echo)—Usesclosely spaced RF excitation pulses and short TR (repetition time) to create asteady-state signal. This sequence produces images with T1 and T2 weighting.

• RSSG (RF Spoiled SARGE)—Uses closely spaced RF excitation pulses withvariable phase shifts. This sequence produces images with T1 weighting.

• TRSG (Time Reversed SARGE)—Acquires the signal that was excited by theprior RF pulse. This sequence produces images with heavy T2 weighting.

• BASG (Balanced SARGE)—Uses a short TR and acquires the signal under asteady state, with slice, phase, and frequency rewinder pulses. This sequenceproduces images with high signal-to-noise ratio (SNR), mixed T1/T2 contrast,and bright fluid.

• FSE (Fast Spin Echo)—Uses multiple 180° RF pulses to more rapidly produceimages with proton density, T1, and/or T2 weighting.

• FIR (Fast Inversion Recovery)—Uses a 180° inverting RF pulse prior to the90° excitation pulse to acquire images with specific tissue suppressions.

• Prime FSE—Similar to FSE, except that the user can enter TE and bandwidthvalues, rather than values for the Inter E. Time (echo interval) and Echo Shiftparameters. (These parameters are described later in this chapter.)

• Prime FIR—Similar to FIR, except that the user can enter TE and bandwidthvalues, rather than Inter E. Time and Echo Shift parameter values.

• DW FSE (Diffusion Weighted FSE)—Optional. Used to acquire diffusion-weighted images by adding an MPG pulse to a RADAR FSE sequence.

• TOF (Time of Flight)—Used to produce MRA using flow/inflow resultsof blood.

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• PC (Phase Contrast)—Optional. Produces MR angiographs using phaseinformation of blood flow.

• SE EPI (Spin Echo using Echo Planar Imaging)—Produces images with T1 orT2 weighting using very short acquisition times.

• GE EPI (Gradient Echo using EPI)—Produces images with T2* weightingusing very short acquisition times.

• DW EPI (Diffusion Weighted EPI)—Produces diffusion-weighted images,which depict the restriction of water molecule diffusion.

• RSSG EPI (RF Spoiled SARGE using EPI)—Optional. Produces images withT1 weighting using short acquisition times.

• Shim (Shimming)—Performs highly precise corrections of the static magneticfield.

• S-Map (Sensitivity Map)—Function performed before the main scan whenusing NATURAL, which is a coil intensity (shading) correction function.

• MRSSE (MR Spectroscopy using Spin Echo)—Optional. Acquires moleculardensities of metabolizing substances in the human body.

EchoTime Mode—Sets the range for the echo time.

For SE sequences, choose one of the following:

• Normal—Use for normal scanning.

• Short TE—Use to acquire images with shorter TE than the Normal setting;however, some parameters such as Dual Slice and Multi Echo will be re-stricted.

For FSE, FIR, Prime FSE, and Prime FIR sequences, choose one of thefollowing:

• Short IET—Use to acquire images with short Inter E. Times, such as 11 andbelow. In the example, Short IET is selected.

• Long IET—Use to acquire thin slice images with Inter E. Times of 12 andabove. This selection is more commonly used than Short IET.



Shim Mode—Provides options for the use of shimming results, as shown inthe example.

• off—Does not use shimming results.

• Volume—Uses volume shimming results. Shimming results are not used whenthere are changes in a patient and coils.

• Regional—Performs regional shimming in a specific area designated by thepurple box on the positioning screen.

Oblique—Provides methods for determining whether or not scans can beperformed, based on the angulation of slices. Select from the following, as shownin the example:

• Full—Allows full angulation of slices, but will require protocol changes if asteep angle is used.

• Limited—Allows a limited degree of angulation, so that the protocol param-eters selected for the acquisition can be used.

Seq. Parameter

The Seq. Parameter section, found under the All tab of Scan Parameters andshown in the example, contains the following parameters:


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FOV—Indicates the size in millimeters of the visual field to be reconstructedfollowing the scan.

TR—Indicates the repetition time in milliseconds of the pulse sequence. (Duringgated scans, TR values are automatically set when Trigger is selected for theGate or Resp mode.)

TE—Indicates the echo period in milliseconds for the first echo. This value isautomatically set when the following Sequences are selected:

• BASG

• FSE

• FIR

• Shim

TE2—Indicates the echo period for the second echo. This setting is displayedwhen the selected Sequence is SE, GE, SARGE, RSSG, or FSE, and theMulti Echo parameter is set to 2 or more. (When FSE is selected, TE2 is auto-matically set based on other parameters, such as E.Factor.)

TE3—Indicates the echo time for the third echo. This setting is displayed whenthe selected Sequence is SE and the Multi Echo parameter is set to 3 or more.

TE4—Indicates the echo time for the fourth echo. This setting is displayedwhen the selected Sequence is SE and the Multi Echo parameter is set to 4 ormore.

The example shows settings for the TE through TE4 parameter fields.

FA (Flip Angle)—The angle of excitation to which the net magnetization is tippedrelative to the main magnetic field.

IR Pulse (Inversion Recovery Pulse)—Indicates if an IR pulse will be used fortissue saturation. This is primarily used with Cardiac scanning.

This parameter can be selected when the selected Sequence is SE, BASG, FSE,DW FSE, DW EPI, SE EPI, or GE EPI.

The following choices are available, as shown in the example:

• Off—Does not perform tissue saturation; this is the recommended setting.

• Single—Performs tissue saturation with designated TI.

Note:TE2, TE3, and TE4 are usedonly for multiple echos.

Note:Additional IR pulse options(Double, Triple) are associatedwith the Cardiac package, whichis a purchasable option.



TI—Sets the Inversion Time, which is the time period between the initial 180°inversion pulse and the 90°excitation pulse in an IR pulse sequence. This field isavailable when the selected Sequence is IR or FIR, the ECG Gate Mode param-eter is Delayed or Myoper, or when the IR Pulse parameter is Single. Themeasurement of the TI will be calculated as follows:

• When the Sequence is IR or FIR, or the IR Pulse parameter is Single, TI is theinterval between the STIR pulse and the excitation pulse.

• When the Gate Mode is Delayed or Myoper, TI is the interval between theSTIR pulse and the zero encode excitation pulse.

IRFA (IR Flip Angle)—Specifies the angulation of the inversion pulse and canaffect the performance of tissue saturation. This angle is entered when theselected sequence is IR or FIR, or the IR Pulse parameter is set to Single.

IR Thickness Rate—Indicates the slice thickness selection of the initial 180°pulse relative to the slice thickness of the main scan. The normal setting for thisparameter is 1.3. You can use this parameter when the selected Sequence is FIRor Prime FIR, or when the Sequence is FSE, Prime FSE, or DW FSE; and theIR Pulse parameter is Single. In the example, the Sequence is FIR and the IRThickness parameter is set to a value of 1.3.

Thickness—Indicates the slice thickness (in millimeters).

Interval—Indicates the spacing (in millimeters) between slices, measuredfrom the center of one slice to the center of the next slice. The interval in2D multi-slice acquisitions is between parallel slices; the interval in 3D multi-slab acquisitions is between parallel slabs.

Multi slice—Indicates the number of slices to be acquired during one scan.This setting is displayed for 2D acquisitions only.

Note:For a FLAIR sequence ofthe brain, the value of theIR Thickness Rate should beset to 4.0.

Note:The gap between slicescan be calculated as:Interval – Thickness = Gap

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Multi Echo—Indicates the number of echoes to be collected in one scan.As the Multi Echo value is increased, additional numbered TE fields (TE2, TE3,and so on) become available. This parameter is available when the selectedSequence is SE, FSE, GE, SARGE, or RSSG. In the example, the Sequence isGE and the Multi Echo parameter is set to a value of 2.

Multi slab—Available for 3D acquisitions only. Indicates the number of sliceslabs to be acquired in one scan. In the example, the Sequence is TOF and theMulti slab parameter is set to a value of 5.

Multi Acquisition—Indicates the number of acquisitions. This setting isaccessible when the selected Mode parameter is Interleaved or Sequential.

When the Mode parameter is Stack, the value in the Multi Acquisition field is notaccessible but will be the same as the value set in the Stacks field, as shown inthe example.



When the Mode parameter is Single Slice, the Multi Acquisition field is notaccessible. However, the displayed number of acquisitions will be the same asthe number set in the Multi slice parameter for 2D acquisitions, or the numberset in the Multi slab parameter for 3D acquisitions, as shown in the examples.

Multi slice Multi slab

The following examples explain how the Multi Acquisition, Mode, and Multi sliceparameters can be set in various combinations to acquire images differently.

Example 1: Multi slice is 6, Mode is Interleaved, and Multi Acquisition is 2.

The Multi Acquisition of 2 divides the slices into two groups of three slices each.The Interleaved mode acquires the top and bottom slices, then the middle slice ineach group, all with the same TR. For these parameter settings, the first acquisi-tion would be slices 1 and 3, and then slice 2; the second acquisition would beslices 4 and 6, and then slice 5.

Example 2: Multi Slice is 6, Mode is Sequential, and Multi Acquisition is 2.

The Multi Acquisition of 2 divides the slices into two groups of three slices each.The Sequential mode acquires the slices in numerical order, one group at a time,all with the same TR. For these parameter settings, the first acquisition would beslices 1, 2, and 3; the second acquisition would be slices 4, 5, and 6.

Example 3: Multi Slice is 6, Stacks is 2, and Mode is Stack.

Stack mode can be used when slices are set at different angles, such as inaxial lumbar imaging. Stack mode acquires the slices in the first stack, thenthe slices in the second stack, all with the same TR. For these parametersettings, the setting of the Stacks value at 2 with the mode set to Stack willcause the Multi Slice field to be updated and display a total of 12 slices(6 slices×2 stacks = 12 total slices).

Example 4: Multi Slice is 6 and Mode is Single Slice.

Single Slice mode is used to acquire one slice per TR, as in 2D TOF sequences.For these parameter settings, each slice (of the 6 total slices) will be acquiredindividually.

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Mode—Specifies the acquisition mode. The choices, as shown in theexample, are:

• Interleaved—Slices are acquired in an odd- and even-numbered fashion (suchas slice numbers 1, 3, 5, 7, then slice numbers 2, 4, 6, 8).

• Sequential—Slices are acquired in order of slice number (such as 1, 2, 3, 4).

• Stack—Slices are acquired for each angle.

• Single Slice—Each slice is acquired as a separate acquisition, with the selectedparameters (one slice per TR).

S.encode—Indicates the number of encodings in the slice direction (the totalnumber of acquired slices). This setting, as shown in the example, is displayedfor 3D acquisitions only.

Stacks—Indicates the number of groups when acquiring multiple groups withdifferent angles.

Freq#—Indicates the number of sampling steps in the frequency axis, as shownin the example. You can hold the pointer over the field to view the range that isavailable.



Phase#—Indicates the number of sampling steps in the phase axis, as shown inthe example. You can hold the pointer over the field to view the range that isavailable.

NSA (Number of Signals Averaged)—Indicates the number of signal acquisitionsto be averaged. Increasing the NSA will improve the SNR of the image, but alsoincreases scan time. Doubling the NSA doubles the scan time, but only increasesthe SNR by approximately 40% because increased noise accompanies theincreased number of signals.

APR[%] (Asymmetric Projection Rate)—Indicates a percentage of K-spacethat will not be acquired in the phase encoding direction. K-space as a whole is100%; the APR[%] parameter can be set to values between 0% and 45% andcan be changed by 5% intervals. This parameter is used in conjunction with HalfScan.

The position of the nonacquired K-space region changes for each of the echolayouts, as shown in the examples. In addition, processing of the nonacquiredregion changes according to the setting of the Half Scan parameter (describednext in this section).

Centric

4 3 2 1 1 2 3 4

APR

Anti Centric

1 2 3 4 4 3 2 1

APR

Sequential

1 2 3

3 4 5

APR

ADA

5 4 3 2 1 3 2 1

APR

Frequency

Phase

Frequency

Phase

Frequency

Phase

Frequency

Phase

Slice

PEAKS RPEAKS

Slice

Phase 1 3 2

1 3 2

4 6 5

8 7 9

11 10 12

APR 1 3 2

4 6 5

7 9 8

11 10 12

14 13 15 APR

Phase

Note:A value must be entered in theAPR[%] field to enable access tothe Half Scan field.

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Half Scan—Enables image acquisition in a shorter time by limiting thesampling of the phase axis in K-space. Spatial resolution is maintained, butSNR is reduced. Images are created using the acquired data, combined withthe interpolated data used to fill the nonacquired region of K-space. Acquisitionsare performed in accordance with the values set for the phase direction in theAPR[%] parameter. The choices, as shown in the example, are:

• off—Does not use Half Scan.

• ON—Uses Half Scan.

The examples explain how the APR[%] and Half Scan parameters functiontogether:

Example 1: APR[%] set at 25(%) and Half Scan set to ON

This is the equivalent of ¾ Scan. Data is acquired from three-fourths (¾) or75% of K-space; one-fourth (¼) or 25% of K-space will be interpolated.

Example 2: APR[%] set at 45(%) and Half Scan set to ON

This is the equivalent of ½ (Half) Scan. Data is acquired from 55% of K-space;45% of K-space will be interpolated.

Shot Num.—Indicates the number of RF excitations, or TR periods, needed toacquire data, as shown in the example. A lower shot number results in a fasterscan time. The shot number can be calculated using the following equation:

Phase Encoding Steps ÷ E. Factor = Shot Number

This parameter is available when the selected Sequence is SE EPI, DW EPI, orGE EPI. Hold the pointer over the field to display the range of settings.

This parameter is displayed, but not accessible, in the following cases:

• Selected Sequence parameter is FSE, FIR, RSSG EPI, or DW FSE.

• Selected Sequence parameter is Prime FSE or Prime FIR, and the Echo Alloc.parameter is set to Centric.



E. Factor—The number of echoes to be used to create a single image. Anacceleration rate is obtained based on the number of echoes used. However, themore the echo is delayed, the weaker the signal strength becomes due to thedecay of signal amplitude (T2 or T2*). As the E. Factor increases, the SNR andresolution decrease.

This parameter is available when the selected Sequence parameter is FSE, FIR,DW FSE, or RSSG EPI.

This parameter is displayed (but not accessible) in the following cases:

• Selected Sequence parameter is SE EPI, DW EPI, and GE EPI.

OR

• Selected Sequence parameter is Prime FSE and Prime FIR, and the EchoAlloc. parameter is set to ADA.

Inter E. Time—The time between echoes. This setting is displayed when theSequence is selected from any of the following: FSE, FIR, SE EPI, DW EPI, GEEPI, or RSSG EPI. When the selected Sequence is FSE or FIR, an effective TEis calculated by the system. This TE calculation includes the E. Factor, EchoAlloc., Echo Shift, and Inter E. Time parameters to determine image weighting.

Echo Shift—Adjusts image contrast by changing the location of the effectiveTE in K-space, without changing the number of echoes. An echo shift of 1changes the effective TE by an increment equal to the value displayed in theInter E. Time field. This setting is available when the selected Sequence is FSE,FIR, SE EPI, GE EPI, RSSG EPI, or DW EPI. This setting is displayed but isnot accessible when the selected Sequence is DW FSE, Prime FSE, or PrimeFIR.

Echo Shift2—Allows you to select the Echo Shift for the second echo. Thisparameter is available when the selected Sequence is Prime FSE or Prime FIR.

Echo Alloc.—Allows you to select the echo layout method (a partial listing ofoptions is shown in the example).

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The choices are:

• Sequential

• Centric

• AntiCentric

• ADA (Asymetric Data Allocation)

• PEAKS (optional)

• RPEAKS (optional)

• TPEAKS (optional)

The Sequence that is selected determines which echo layouts will be available.Sequential, Centric, AntiCentric, and ADA are frequency/phase 2D echo layouts.

The nonacquired region will be determined in combination with the value set inthe APR[%] parameter. Processing of the nonacquired region will changeaccording to the value set in the Half Scan parameter. (For example, Half Scanis automatically set when ADA is selected.)

Frequency

Phase

Frequency

Phase

Centric

4 3 2 1 1 2 3 4

Anti Centric

1 2 3 4 4 3 2 1

Sequential

1 2 3 4 5 6 7 8

ADA

8 7 6 5 4 3 2 1

Frequency

Phase

Frequency

Phase

PEAKS and RPEAKS are optional phase/slice 2D echo layouts, which areused during 3D contrast-enhanced MRA. Acquisition is started in the directionof the epicenter of K-space. When the epicenter is acquired, acquisition isperformed receding from the epicenter. When the APR[%] parameter is 0, thereis no difference between PEAKS and RPEAKS. However, when the APR[%]parameter is set to anything above 0, the nonacquisition region differs. Process-ing of the nonacquired region will change according to the value set in theHalf Scan parameter.

Slice

Phase

Slice

Phase

PEAKS

1 3 2

1 3 2

4 6 5

8 7 9

11 10 12

APR

RPEAKS

1 3 2

4 6 5

7 9 8

11 10 12

14 13 15 APR



TPEAKS is an optional phase/slice 2D echo layout, which is used during3D contrast-enhanced MRA in the same way as PEAKS and RPEAKS. Thedistance between the center of the phase/slice plane and each acquisition pointis used as the standard to set the acquisition order. As shown in the example,acquisition is performed from the center of the phase/slice plane, with the timethat K-space data collection begins as the peak of the contrast agent density.Acquisition is then performed on the side closest to the center.

Additional selections for the Echo Alloc. parameter are available with theTIGRE measurement function. (The TIGRE sequence is described in moredetail in the “TIGRE” section of this chapter.) To access these additional selec-tions, parameters must be set as follows:

• 2D/3D field—3D

• Sequence field—RSSG

• Saturation field—Segment FS

As shown in the example, the additional Echo Alloc. selections for TIGREinclude:

• Cent-Cent—Echo allocation for both the phase and slice encode directions isCentric.

• Cent-Seq—Echo allocation for the phase encode direction is Centric, while theecho allocation for the slice encode direction is Sequential.

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Chemical Shift—Indicates the optimum polarity of the phase-encoding gradientmagnetic field. The polarity can be changed to minimize the effects of imagedistortion. This setting is available when the selected Sequence is SE EPI,GE EPI, DW EPI, or RSSG EPI, and the Echo Alloc. parameter is set toSequential or ADA. As shown in the example, the options are:

• Normal—Normal polarity of the phase encoding gradient magnetic field.

• Reverse—Reverse polarity of the phase encoding gradient magnetic field.

DE Pulse (Driven Equilibrium Pulse)—An additional pulse that can be usedfollowing signal collection to possibly decrease TR and consequently decreasescan time, while maintaining T2 contrast. A DE pulse converges the transverserelaxation of the magnetization and forces it to longitudinal relaxation. Thissetting is available when the selected Sequence parameter is FSE, FIR, PrimeFSE, Prime FIR, or DW FSE. The following options are available, as shown inthe example:

• off—Does not add the DE pulse.

• ON—Adds the DE pulse.



Advanced

The Advanced section, found under the All tab of Scan Parameters and shown inthe example, contains many additional parameters that can be used during imageacquisitions.

The Advanced parameters are described below:

Presat (Presaturation)—Allows you to apply presaturation pulses that canreduce artifacts by controlling the signals from movable areas (such as bloodflow signal or the abdominal wall).

Presaturation is a technique that uses repeated RF excitation of structuresadjacent to the anatomy of interest to reduce or eliminate the phase effectartifacts that can be caused by flowing nuclei in these adjacent structures. Thesignal from the flowing nuclei is saturated, and therefore nullified, upon enteringthe FOV.

You can set up to a maximum of eight presats, with the Presat field displayingthe total number. The first two presats are automatically set as parallel regionsadjacent to the slice surface. These two regions prevent the blood flow signalfrom flowing into the slice plane to be scanned. Presats are displayed in blue.The mouse can be used to rotate, move, or magnify the presat regions.


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Walking—Allows the position of the presat region to move, or “walk,” foreach slice acquired (or each slab in 3D). In this manner, the presat alwaysremains adjacent to the slice. This is used when acquiring blood vessel imagesin angiography.

This setting is available when the selected Sequence is TOF or BASG. If awalking presat is selected, it is the first presat displayed in the viewport, and it isdisplayed in green. Only one walking presat is available. The mouse can be usedto rotate, move, or magnify the walking presat region. The number displayed inthe Presat parameter field is the total number of presats, including the walkingpresat.

The example shows a walking presat.

Intermittent—Applies presats for each repetition time (which is the value set inthe TR parameter); normally, the presat is applied for each slice acquisition.Intermittent presats will allow you to increase the number of slices; however asthe TR increases, the effectiveness of the presat decreases.

The maximum number of intermittent presats available is 2. The intermittentpresats will be displayed in light blue. The mouse can be used to rotate, move, ormagnify the intermittent presats. The number displayed in the Presat field is thetotal number of presats, including the intermittent presats.



The examples show the Intermittent parameter with values of 1 and 2.

Intermittent parameter set to 1

Intermittent parameter set to 2

6Scan Parameters

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Segment—May improve presat results. Available when the selected Sequenceis BASG, and one or more presats have been selected. The example shows theSegment parameter set to 1.

Dual Slice—Acquires twice as many images with the same scan parameters byacquiring two parallel slices at a time. The number that can be entered in theMulti slice field is doubled. An even number is required in the NSA parameterfield. Dual Slice is available when the selected Sequence is SE, IR, or GE. Thechoices for this parameter, as shown in the example, are:

• off—Does not use dual slice.

• ON—Uses dual slice.

Rephase (Flow Compensation)—Used to suppress flow artifacts, such as bloodand CSF. The options, as shown in the example, include:

• off—No rephase.

• Slice—Rephase is applied along the slice direction only.

• Freq.—Rephase is applied along the frequency direction only.

• Slice-Freq.—Rephase is applied along the slice and frequency directions.

The Rephase directions that are available depend on the Sequence that isselected. For multi-echo acquisitions, Rephase can be applied to the first andsecond echo. Rephase can be used with the following Sequences: SE (secondecho only), GE, SARGE, RSSG, FSE, Prime FSE, or DW FSE.



Bandwidth (kHz)—Indicates the frequency bandwidth of the reception signal,as shown in the example. Since noise is distributed evenly across all frequencybandwidths, reducing the frequency bandwidth value reduces noise and improvesthe SNR; however, chemical shift artifacts may become more noticeable.

Bandwidth2—Indicates the frequency bandwidth (kHz) of the receptionsignal for the second and subsequent echoes during a multi-echo acquisition.This parameter is available when the selected Sequence is SE, GE, SARGE, orRSSG, and the Multi Echo parameter (under Seq. Parameter) is set to 2 or more.

In the example, the Multi Echo parameter is set to 2, and the Bandwidth2parameter is set to 10.

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AMI (Asymmetric Measurement Imaging)—Indicates the percentage (usually20% to 30%) of the early portion of the echo signal that will not be measured,as there is more noise in the beginning of the echo signal (as shown in theexample). Asymmetric measurement imaging allows the user to shorten theTE and increase the number of slices, and may result in improved contrast onT1-weighted images. However, if AMI is set to 30% or higher without settingthe Half Echo parameter to ON, spatial resolution may be degraded. (The HalfEcho parameter is described next in this section.)

100%

Asymmetric measurementimaging (%)

Frequency direction GC

Echo signal

Half Echo—Prevents degradation of spatial resolution during AMI. The HalfEcho function creates an image by estimating the uncollected data, based on thecollected data, in the frequency direction. It allows for the use of a shorter TE,or lower bandwidth. The options are:

• off—Does not use half echo.

• ON—Uses half echo.

Rect.FOV (Rectangular Field of View)—Reduces the number of acquisitionpoints in the phase direction (set in the Phase# parameter). This parameter isused to match the size of the phase encoding direction for the scan target, aswell as for the FOV that has been set.

The scan time will be reduced by the amount that the value of the Phase#parameter is reduced. Although the spatial resolution is the same as for a normalscan, the SNR will be reduced in accordance with the number of reductions inthe phase encoding direction.

As shown in the example, the options include:

• off—Does not use Rect.FOV.

• Auto—Acquires the size of the patient in the phase encoding direction, andthen automatically determines the FOV actually acquired and the number ofacquisition points in the phase direction.

• Manual—Allows the user to select the size of the rectangular FOV.

Note:The Half Echo function usesfrequency direction data in thesame manner that the Half Scanfunction uses phase directiondata.



Size[%]—Available when the Rect.FOV parameter is set to Manual.Allows you to enter the size of the rectangular FOV to be acquired;this value is displayed as a percentage of the current FOV parameter(under Seq. Parameters). The example shows a Size[%] parameter set to 80,meaning the FOV will be reduced by 20% in the phase encoding direction.

Anti.aliasing—Removes aliasing artifacts that are produced when the patientis larger than the FOV in the phase encoding direction. Anti-aliasing is alsoeffective in reducing motion artifacts in certain anatomic regions (such as thechest or abdomen).

As shown in the example, the options include:

• off—Does not use anti-aliasing.

• Auto—Acquires the size of the patient in the phase encoding direction. TheFOV that is actually acquired and the number of acquisition points in the phasedirection are automatically determined based on the value of the Mode param-eter, which is described next in this section. The available Mode values will beRes and Time.

• Manual—Allows you to enter the FOV size in the Size[%] parameter. Theavailable Mode values will be Res, Time, and TimeRes.

Mode—Specifies the manner in which anti-aliasing is performed: maintainingspatial resolution, maintaining scan time, or both. The following options arealways available:

• Res—Spatial Resolution Mode. Increases the number of acquisition points inthe phase direction according to the value of the Size[%] parameter. Thespatial resolution is maintained, but the scan time increases based on the valueof the Size[%] parameter.

• Time—Scan Time Mode. Increases the acquisition FOV according to thevalue of the Size[%] parameter, but does not change the number of acquisitionpoints in the phase direction. The scan time is maintained, but the spatialresolution decreases based on the value of the Size[%] parameter.

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The following additional mode is available when the Anti.aliasing parameter is setto Manual:

• TimeRes—Scan Time/Spatial Resolution Mode. Doubles the number ofacquisition points in the phase direction and reduces the effective NSA by half.The NSA parameter field must be set to an even number. The SNR, scan time,and spatial resolution are all maintained.

The examples show the Mode options.

Mode options when Anti.aliasing is Mode options when Anti.aliasing isset to Auto set to Manual

Size[%]—Indicates the size of the FOV that is measured when the Anti.aliasingparameter is set to Manual. This number represents a percentage of the numberentered in the FOV parameter (under Seq. Parameters). If the selected Mode isTime/Res, the Size[%] parameter will default to 200. The example shows aSize[%] parameter set to 150.

# RF Prep—Allows you to enter the number of reserve RF excitations priorto scanning. This value can affect both image contrast and artifacts. Thisparameter is available when the selected Sequence is BASG.

Dummy Echo—Allows you to skip the short TE signal component whenacquiring heavily T2-weighted images. This parameter is available when theselected Sequence is Prime FSE or Prime FIR.

RF Phase—Allows you to enter the phase angle of the RF pulse when theRF pulse is used to control the previous excitation signal. The unit is degrees.This parameter is available when the selected Sequence is BASG or PBSG. Thisparameter is displayed but not accessible when the selected Sequence is RSSG,TOF, PC, or RSSG EPI.



The example shows that the selected Sequence is BASG, with # RF Prep setto 37 and RF Phase set to 117.

Phase Dir. A—Specifies the phase encoding direction for the axial plane. Thisparameter is available when the selected Slice Plane is AX, SA, CA, or SCA.As shown in the example, the options are:

• A-P—Sets the phase encoding direction as Anterior-Posterior.

• R-L—Sets the phase encoding direction as Right-Left.

Phase Dir. S—Specifies the phase encoding direction for the SAG plane. Thisparameter is available when the selected Slice Plane is SAG, SA, SC, or SCA.As shown in the example, the options are:

• A-P—Sets the phase encoding direction as Anterior-Posterior.

• H-F—Sets the phase encoding direction as Head-Foot.

Phase Dir. C—Specifies the phase encoding direction for the COR plane. Thisparameter is available when the selected Slice Plane is COR, CA, SC, or SCA.As shown in the example, the options are:

• R-L—Sets the phase encoding direction as Right-Left.

• H-F—Sets the phase encoding direction as Head-Foot.

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RADAR

RADAR (RADial Acquisition Regime) is a nonorthogonal sampling scan func-tion, which samples K-space in a radial pattern. It is used to reduce motionartifacts.

The RADAR section, found under the All tab of Scan Parameters and shown inthe example, contains the following parameters:

RADAR—Specifies whether the RADAR function is ON or off. RADAR canbe used when the selected Sequence is 2D/3D FSE, 2D/3D FIR, or 2D DWFSE.

Proj#—Displays the total number of acquired echoes. This number is setautomatically, according to the value of the Phase # parameter (in the Seq.Parameter area).

E. Factor—Select the number of echoes to be acquired per Blade. As theE. Factor increases, the scan time decreases.

Blade—Displays the number of Blades to be used in the RADAR acquisition.The system automatically calculates and displays the number of Blades, basedon the values of the Proj.# and E. Factor parameters. (The Blade value willapproximate the Proj.# value divided by the E. Factor value, as inBlade = Proj.# ÷ E. Factor).

The examples show the relationship between the Blade and E. Factor values.

Note:Blade refers to a segmentedarea that rotates in themeasurement space.



Saturation

The Saturation section, found under the All tab of Scan Parameters, contains thefollowing parameters:

Saturation—Provides the following options for suppressing specific signals, asshown in the examples:

• off—Does not perform signal suppression.

• FatSat—Suppresses MR signals produced by fat elements by eliminatingspecific RF waves. When you select FatSat, you will also select the Wave,Duration, and RF amp parameters. The maximum number that can be set inthe Multi slice parameter (in the Seq. Parameter area) may be reduced if theTR is to be maintained. In addition, the SNR may decrease and contrast maychange, depending on the values selected for the Duration and Off.Freqparameters.

• Segment FS—Segmented fatsat pulse used with TIGRE sequences to maintainfat suppression in dynamic scans.

• PhaseCycle—Scanning is performed multiple times and fat signals are selec-tively suppressed. The Multi scan mode must be set to Fluoro or Dynamic andthe selected sequence must be BASG.

• Water Excitation—Water magnetization is selectively excited and fat magneti-zation is suppressed. Smaller composite pulses (that add up to 90°) are used;only water protons are flipped to the transverse plane and can emit a signal.

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Additional Parameters for FatSat Saturation

When the Saturation selection is FatSat, as shown in the example, the followingadditional parameters are available:

Wave—Provides options for the waveform of the fatsat pulse, as shown in theexample. Each of these waveforms maintains a minimum TR, which limits thenumber of slices available. H-Sinc Light suppresses lipids. H-Sinc Heavysuppresses lipids and fatty protons, which precess at the same frequency aswater.

When acquiring T2-weighted images with a large FOV, the following settings arerecommended:

• Sinc—When the selected Sequence is DW EPI

• H-Sinc Light or H-Sinc Heavy—When the selected Sequence is FSE, PrimeFSE, or DW FSE

Duration—Allows you to enter the time in milliseconds for the fatsat pulse.This value determines the frequency bandwidth for the patient signal that issuppressed by the fatsat pulse. Time and frequency bandwidth are inverselyrelated (for example, a shorter time results in a wider bandwidth).

RF amp.[%]—Allows you to enter the strength (RF amplitude) of the fatsatpulse. If this value is changed, the suppression effects of fat signals will change.100% of the initial value is the optimal strength calculated from the Wave andDuration parameters.

Off.Freq[Hz]—Displays the frequency difference (in Hz) between the fat peakand the water peak. This value is field-strength-dependent and should not bechanged. At 1.5T, the value is -224Hz. This field is not available when theFreq. graph field is set to Auto or ON.

Segment—May be used to improve fat suppression results when the selectedSequence is BASG and the selected Saturation parameter is FatSat. Increasingthe segment number divides the fatsat pulse into segments. This may decreasescan time, but also decreases the effectiveness of the fatsat pulse.

Definition:Precession refers to thesecondary spin of hydrogennuclei when placed within amagnetic field.



Additional Parameters for Segment FS Saturation

When the Saturation selection is Segment FS (for use with TIGRE sequences),the Wave options include Sinc and H-Sinc, as shown in the example. Therecommended wave is H-Sinc, as it provides more consistent fat suppression.

Additional Parameters for Phase Cycle Saturation

When the Saturation selection is Phase Cycle, the following additional parameteris available, as shown in the example:

Quasi TimeRes—May improve time resolution by sharing data. This parameteris available only when the selected Multi scan mode (in the Scan Control area) isFluoro or Dynamic.

Additional Parameters for Water Excitation Saturation

When the Saturation selection is Water Excitation, as shown in the example, thefollowing additional parameter is available:

Wave—Indicates the wave for the RF excitation pulse; each group of compositepulses adds up to 90°. As the pulse number increases (and the total pulse islonger), the water selection increases and the fat suppression effects improve;however, the images will have more noise. The following options are available:

• 1-1—One 45° pulse, one 45° pulse.

• 1-2-1—One 22.5° pulse, one 45° pulse (2×22.5°), one 22.5° pulse.

• 1-3-3-1—One 11.25° pulse, one 33.75° pulse (3×11.25°),one 33.75° pulse (3×11.25°), one 11.25° pulse.

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Freq. Graph Parameter

All Saturation selections include the Freq. graph parameter, which is explainedbelow.

Freq. graph—Determines whether or not to display a frequency graph inthe Frequency Prescan window, which is described in the next section. Thefollowing options are available, as shown in the example:

• off—Does not display the frequency graph.

• Auto—When the offset frequency for the fatsat pulse is determined in theExam window, that value is used during the acquisition. This setting can onlybe used when the Saturation parameter is FatSat.

• ON—Displays the frequency graph.

Frequency Prescan Window

The Frequency Prescan window, as shown in the example, displays thefrequency graph results. This window will appear at the beginning of a scanwhen the Freq. graph parameter is set to ON or when it is set to Auto and theSaturation parameter is Fat Sat.

This window contains the following features:

Frequency (MHz)—Displays the center frequency of water (MHz).

Offset Frequency (MHz)—Represents the precessional frequency difference(Hz) between fat and water. This value is field-strength-dependent and shouldnot be changed. At 1.5T, the value is -224Hz; this is the frequency of the fatsatpulse.

Noise Threshold (%)—Used when the Weighted method is selected for theSearch Mode parameter, which is described next in this section. This parameterallows you to select the threshold percentage for determining the center fre-quency by the center of gravity method.

Water peak

Fat peak



Search Mode—Allows you to select the search method for determiningfrequency values from the following options:

• Peak—Peak method, where the center frequency is set at the signal’smaximum frequency value.

• Weighted—Center of gravity method, where the center frequency is set atthe center of gravity for signal values at or greater than the threshold.

Reset Param—Returns the values on this window to their initial settings.

CONTINUE button—Restarts the scan.

STOP button—Stops the scan.

The graph display, as shown in the example, has the following features:

• Vertical axis—Signal value

• Horizontal axis—Frequency (MHz)

• Green vertical line—Offset frequency (fat peak)

• Blue vertical line—Center frequency (water peak)

• Red horizontal line—Threshold when using the center of gravity method (notshown in the example)

• Orange point—Acquisition data point (located on the blue vertical line in theexample)

CautionIf the center frequency is changed on the graph of the frequency prescanresults, there will be an offset produced in the position of the acquisition plane.The reference image (scanogram) should be rescanned.

Note:Hitachi Medical SystemsAmerica, Inc. (HMSA) recom-mends use of the Peak method.

Offset frequencyFat peak

Center frequencyWater peak

Signal valueaxis

Frequency (MHz) axis

Acquisitiondata point

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While the graph is displayed, if prescanning is canceled using the Stop button onthe Frequency Prescan window or the Abort button on the control panel, thefrequencies that have been set will not be applied to all subsequent acquisitions.

In addition, once the center frequency and offset frequency have been set, theywill be maintained until one of the following types of acquisitions is performed:

• Acquisition with the Freq. graph parameter set to ON.

• Acquisition with the Prescan parameter set to ON.

• Acquisition with the Exam window changed (for example, the Sequence orother parameters have been changed).

• Acquisition with the receiver coil changed.

MTC

The MTC (Magnetization Transfer Contrast) section of the Scan Parameters Alltab, shown in the example, contains the following parameters:

MTC—Changes the contrast of images by changing the magnetization move-ment between bound water and free water. The MTC pulse is activated prior toslice plane excitation.

Wave—Select the waveform of the MTC pulse from a drop-down menu, asshown in the example.

The waveforms options are Sinc and Gaussian, which differ in function as shownin the examples.

RF amp.

Duration

Gaussian function type

Duration

Sinc function type

RF amp.

Note:HMSA recommends the useof Sinc for the waveform.



Duration—Indicates the activation time in milliseconds for the MTC pulse.This value determines the frequency bandwidth of the MTC pulse. A shorterduration produces a wider frequency bandwidth and a longer duration timeproduces a narrower frequency bandwidth.

RF amp.[µT]—Indicates the activation strength (RF amplitude) of theMTC pulse (in mT).

Off.Freq[kHz]—Indicates the offset frequency (in kHz) of the MTC pulse.

VENC

The VENC (Velocity Encoding) function uses phase information to acquirethe flow rate and flow direction of blood. The VENC section, found under theAll tab of Scan Parameters and shown in the example, contains the followingparameters:

VENC—Available when the selected Sequence is Phase Contrast. WhenVENC is set to ON, a flow encode pulse is applied to target the blood flow.

The following parameters are available when VENC is set to ON:

Target Vel.—Indicates the flow rate for the target vessel in centimeters persecond. This value is a vector volume with size and direction. The value of thisparameter is the maximum value that can be acquired on the flow rate image;however, flow rates that exceed the value set will be acquired as flows in thereverse direction.

VENC Dir#—Indicates the number of axes where the flow encode pulse willbe applied. Provides the following options, as shown in the example:

• 1—Applies the flow encode pulse to one axis. Use the VENC Dir. Parameter(described next in this section) to select this axis.

• 3—Applies the flow encode pulse to the following three axes: the A-P axis(front-back direction), the R-L axis (right-left direction), and the H-F axis(body axis direction).

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VENC Dir.—Available if 1 is set for the VENC Dir# parameter. Allows you toselect the one axis to which the flow encode pulse will be applied. As shown inthe example, the options are.

• A-P—Applies the flow encode pulse to the A-P axis.

• R-L—Applies the flow encode pulse to the R-L axis.

• H-F—Applies the flow encode pulse to the H-F axis.

Vel. Image—Reconstructs a flow velocity image in each axis, in addition to thedifferential combination image.

Comb. Image—Reconstructs the differential combination image (angiographyimage); defaults to ON. These images can be used for the MIP post-processingtask. This task is described in the “Task MIP” section of Chapter 8, “PostProcessing Tasks.”

SSP

The SSP section, found under the All tab of the Scan Parameters area andshown in the example, contains the following parameters:

SSP (Sloped Slab Profile)—Applies an RF pulse using gradient profile excitationto minimize the saturation of blood flow within a volume (slab). This parameter isavailable when the selected Sequence is TOF and the 2D/3D parameter is set to3D. Changing the RF excitation angle inside the slab affects the spins (in theflowing blood) as they move through the volume. A smaller angle is needed forblood entering the volume; the angle should increase as the blood flows throughthe volume.

Rate—Indicates the RF pulse ratio (slope) of inflow region to outflow region. Alarger volume demands a steeper slope, as it takes more time for blood to flowthrough this larger area. The options are:

• 1.5—The ratio will be 1:1.5 (smallest slope).

• 2—The ratio will be 1:2.

• 2.5—The ratio will be 1:2.5.

• 3—The ratio will be 1:3 (steepest slope).



Direction—Specifies the RF pulse gradient direction. You can select one of thefollowing options to increase the RF pulse in the specified direction:

• F<H—Increases from feet to head.

• H<F—Increases from head to feet.

• R<L—Increases from right to left.

• L<R—Increases from left to right.

• A<P—Increases from anterior to posterior.

• P<A—Increases from posterior to anterior.

The options that can be selected for each slice plane are as follows:

• For AX—F<H and H<F

• For SAG—R<L and L<R

• For COR—A<P and P<A

Example: For the Circle of Willis (COW), the F<H direction would be used. Thisplaces the smaller angle at the feet, where the blood enters the volume.

MPG

Motion Probing Gradients (MPG) are the gradient magnetic fields used indiffusion weighted imaging. These gradients are needed when imaging the protondiffusion phenomenon. The MPG selection is available when the selectedSequence is DW FSE or DW EPI.

The MPG section, found under the All tab of Scan Parameters, contains thefollowing parameters:

MPG (Motion Probing Gradient)—Specifies if the MPG function is ON or off.

MPG Dir#—Select the number of axes to which the MPG pulse is applied.The following options are provided, as shown in the example:

• Single—Applies the MPG pulse to the A-P, R-L, or H-F axis.

• Trace—Applies the MPG pulse to the three axes in sequence.

• Tensor6—Applies the MPG pulse to six axes, which includes A-P, R-L, H-F,and three oblique directions: A-P with R-L, A-P with H-F, and H-F with R-L.(This is a purchasable option associated with the Tensor Suite.)

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Gradient Mode—Indicates the mode to which the MPG pulse is applied.The following options are provided, as shown in the example:

• Single—Applies the MPG pulse to the axis selected under MPG Dir #.

• Complex—Applies the MPG pulse to the three axes (A-P, R-L, H-F).

This parameter is not available when the MPG Dir# parameter is set to Tensor6.

b-factor—Allows you to enter the b-factor of the MPG pulse. The applicationtime and application strength of the MPG pulse are automatically calculatedbased on the b-factor value.

MPG Dir.—Allows you to select the application axis. This parameter is avail-able when the entry in the MPG Dir# field is Single. The following options areprovided, as shown in the example:

• A-P—Applies the MPG pulse to the A-P axis.

• R-L—Applies the MPG pulse to the R-L axis.

• H-F—Applies the MPG pulse to the H-F axis.

Note:HMSA recommends usinga b-factor of 1000.



Scan Control

The Scan Control section, found under the All tab of Scan Parameters andshown in the example, contains the following parameters:

Scan mode—Specifies the mode, if scans are to be repeated. The followingoptions are provided, as shown in the example:

• Once—Repeats only once.

• Discontinuous—The system asks with each repetition whether to perform thescan or not.

• Every—Performs a scan the number of times equal to the value set in theRepeat Number parameter, described later in this section.

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Multi scan mode—Specifies the performance mode for the scan. Thefollowing options are available, as shown in the example:

• Normal—Performs a normal scan.

• Dynamic—Performs a scan that repeats multiple times. The time interval forscans to be repeated can be set.

• Fluoro—Repeats a scan a number of times in as short a period as possible.During scanning, parameters can be changed in real time.

Wait mode—Specifies the scan wait mode. The following options are available,as shown in the example:

• off—Does not pause before starting a scan.

• ON—Pauses before starting the scan once the prescan is finished; timing ofthe pause is determined by the value in the Wait# field.

Wait#—Indicates the number of acquisitions the system will perform prior topausing. You can specify this setting when the Multi Scan mode is set to Normalor Dynamic, the Wait mode parameter is ON, and the Multi Acquisition param-eter (under Seq. Parameter) is set at 2 or more. The Wait# must be one numberlower than the value in the Multi Acquisition field. The following options areavailable:

• 0—Scanning is performed continuously.

• 1—Pauses once before starting the main acquisition; the system counts theprescan as the first acquisition.

• 2 or more—Pauses after performing two or more acquisitions, dependingon the number of acquisitions set in the Multi Acquisition parameter. (Forexample, with Multi Acquisition set to 5, and the Wait# set to 3, the systemwill perform the prescan and two additional acquisitions before pausing).

After pausing, left-click on the CONTINUE button to resume scanning, asshown in the example.



Start wait time—Sets the wait time before the scan starts. This is displayed asminutes:seconds.tenths of seconds, as shown in the example. This parameter isonly available when the Multi scan mode is Normal and the Wait mode is off.

Repeat Number—Specifies the number of repetitions of the scan. This param-eter is only available when the Multi scan mode is Normal and the Wait mode isoff.

No of scan set—Allows you to specify the number of scan repetitions and therepetition interval (or wait) for each set (scans can be divided into a number ofsets with a maximum of 3). This parameter is available when the Multi scanmode parameter is set to Dynamic.

Pre-Cont. (Pre-Contrast)—Specifies the number of repetitions for the first setof scans. The diagram below indicates three repetitions for this first set.

delay time (for Pre-Cont.)—Specifies the wait time for the start of the first set.This is displayed as minutes:seconds.tenths of seconds.

gap time (for Pre-Cont.)—Specifies the interval (in seconds) between repeti-tions of the first set. The Pre-Cont. field must be set to 2 or more.

Scan#1

1st Gap Time Scan#2

Scan#3

1st Gap Time

Individual Scan Time Individual Scan Time Individual Scan Time

wait mode (for Pre-Cont.)—Provides the following options for the wait modefor repetitions of the first set:

• off—Does not pause when starting.

• Every—Pauses with each repetition. Eliminates the gap time field.

• Once—Pauses only for the first repetition.

After pausing, left-click on the CONTINUE button to resume scanning.

Early Post Cont. (Early Post Contrast)—Specifies the number of repetitionsfor the second set of scans. This parameter is available when the No. of scanset parameter is set to 2 or 3.

delay time (for Early Post Contrast)—Specifies the wait time for the start ofthe second set. This is displayed as minutes:seconds.tenths of seconds.

gap time (for Early Post Contrast)—Specifies the interval (in seconds) betweenrepetitions of the second set. The Early Post Cont. parameter must be set at 2 ormore.

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wait mode (for Early Post Cont.)—Provides the following options for the waitmode for repetitions of the second set:





Late Post Cont. (Late Post Contrast)—Allows you to specify the number ofrepetitions for the third set of scans. This parameter is available when the No. ofscan set parameter is set to the maximum value of 3, as shown in the example.

delay time (for Late Post Contrast)—Specifies the wait time for the start of thethird set. This is displayed as minutes:seconds.tenths of seconds.

gap time (for Late Post Contrast)—Specifies the interval (in seconds) betweenrepetitions of the third set. This parameter is available when the Late Post Cont.field is set at 2 or more.

wait mode (for Late Post Contrast)—Provides the following options for the waitmode for repetitions of the third set.







Contrast agent—Provides options for selecting the name of a contrast agent tobe used, as shown in the example. If the Multi scan mode is Dynamic, the No. ofscan set field must be at a value greater than 1 to have access to this field. Thecontrast agent list can be customized in the Patient Registration Setting window.Refer to Chapter 4, “Patient Information Functions,” for more information on thiscustomization.

Volume[ml]—Available when a contrast agent name is selected. Sets thevolume of contrast agent to be used in milliliters, as shown in the example.

Travel Time—Used during contrast-enhanced magnetic resonanceangiography (CE-MRA). Enter the time it will take for contrast to arrive atthe target area, which is determined from the test injection during the dynamicscan measurement.

Additional fields displayed under Travel Time include:

OffsetTime—Used during CE-MRA. Displays the time that should be the initialsetting for the stop watch. The contrast agent is to be injected when the stopwatch reaches zero.

ContinueTime—Used during CE-MRA. Displays the timing when the contrastagent is injected and the CONTINUE button is selected.

Org. Image—Specifies whether or not to reconstruct the source images, asshown in the examples. This parameter is available when the selected Multi scanmode is Dynamic or Fluoro, and the Sub. Image parameter (described next inthis section) is set to Fixed, Moved, or FxMv.

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Sub. Image—Specifies the method for creating subtraction images fordynamic scans. This parameter can be set when the Multi scan mode parameteris Dynamic or Fluoro. The following options are available, as shown in theexample:

• off—Does not create a subtraction image.

• Fixed—Creates subtraction images using the first scan as the mask for allsubsequent scans (fixed mask).

• Moved—Creates subtraction images in which each scan uses the previousscan as its mask (moved mask).

• FxMv—Creates both types of subtraction images: fixed and moved.

The examples show how fixed and moved subtraction images are created:

Example: In fixed subtraction, scan 1 is subtracted from scan 2, scan 1 issubtracted from scan 3, and so on. The mask is fixed using scan 1.

Example: In moved subtraction, scan 1 is subtracted from scan 2, scan 2 issubtracted from scan 3, and so on. The mask moves from scan to scan.

4-1Fixed–subtracts 3-12-1

4-3Moved–subtracts 3-22-1



Sub. Mask Start#—Allows you to enter the number of the scan that starts thesubtraction processing when performing dynamic or fluoro scans. A black image(an image with all pixel values set to 0) is output until the start of subtractionprocessing. The examples show how images are created when the value for thisparameter is set to 3.

Example: Fixed mask subtraction, where scan 3 is the mask scan.

Example: Moved mask subtraction, where scan 3 is the first mask scan.

Disk save—Available when the Multi scan mode parameter is set to Fluoro.Provides a drop-down menu, as shown in the example, with the following optionsfor saving images to the database.

• off—Only the images for which the SAVE button on the Exam window isselected will be saved to the database.

• ON—Saves all images to the database.

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Table move—Provides the following options for moving the patient table, asshown in the example:

• off—Does not move the table.

• Centering—Moves the table to the center of the magnetic field, depending onthe position of the acquisition plane.

• Manual—Moves the table to the position that has been entered in the Positionparameter (described next in this section).

Position[mm]—Available when the Table move parameter is set to Manual.Allows you to enter the distance of patient table movement in millimeters, asshown in the example.

Auto Voice—Specifies whether or not to output an auto voice pattern. The autovoice pattern can be created in the Auto Voice Setting window, as shown in theexample. For more information about creating an auto voice pattern, see the“Auto Voice Setting Window” section of Chapter 9, “Additional LauncherFunctions.”

After creating a new auto voice pattern, you will need to close and reopen theExam window; the Auto Voice option will then become available.

Path:System Settingsdrop-down menuAuto Voice Settingmenu optionAuto Voice Settingwindow



Sync. StopWatch—Starts the timing in the StopWatch window simultaneouslywith the acquisition. You can choose from the following options, as shown in theexample:

• off—Does not synchronize the start of the StopWatch with the acquisition.

• ON—Synchronizes the start of the StopWatch with the acquisition.

Prescan—Specifies the prescan mode. You can choose from the followingoptions, as shown in the example:

• Auto—Automatically performs appropriate prescan measurements based ondata from the previous scan.

• ON—Performs prescan measurements at the beginning of the first scan,acquiring new data. This setting should be used on the first scan for each newpatient.

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RAPID

The Rapid Acquisition through a Parallel Imaging Design (RAPID) functionshortens the scan time. By using multiple channel receiver coils, phase encodingis decreased during the acquisition according to the value set in the RAPIDparameter field.

Generally, when decreasing the phase encoding for an acquisition, aliasing isproduced in the image following reconstruction. The RAPID acquisition functionacquires the data using multichannel receiver coils. It develops the image using asensitivity map of the receiver coils, thus eliminating aliasing and shortening thescan time. The SNR of the image is reduced as the value of the RAPID param-eter is increased.

The example shows how the RAPID function creates images.

Coil sensitivity map

Aliased image

Image development anti-aliasing

Resulting image

The RAPID section, found under the All tab of Scan Parameters, contains thefollowing parameters:

RAPID—Decreases the phase encoding in the acquisition according to thevalue entered in this field. For example, when the RAPID parameter is set to2.0, phase encoding is decreased by 50% and the scan time is reduced by abouthalf. The RAPID value can be set in the range from 1.0 to 4.0, with a precisionof 0.1 step. A RAPID acquisition is not performed when the RAPID parameteris set at 1.0, which is the default value.



Mode—Specifies the calibration method for the RAPID acquisition. Themethod may be selected automatically, based on the Sequence that has beenselected. The following options are available, as shown in the example:

• PCM (Prescan Calibration Method)—Acquires the coil sensitivity map duringprescan. The additional parameter options available with this method aredescribed next in this section.

• SCM (Self Calibration Method)—Acquires the coil sensitivity map during theRAPID scan. This is the default method when certain sequences are selected.

When PCM is selected as the Mode parameter, the following additional param-eters are available:

PCM Mode—Determines the control method for collecting a coil sensitivitymap during prescan. The default value is Auto, as shown in the example.

The following options are available on a drop-down menu, as shown in theexample:

• Auto—Automatically determines whether or not to use the coil sensitivity mapcollected during the previous prescan. If it can be used, reacquisition of the coilsensitivity map is not performed. If there is no previous coil sensitivity map, itis collected. Reacquisition of the sensitivity map will not be performed if thefollowing conditions are the same as during the previous collection:

– Slice position, oblique angle, slice interval

– Slice plane, phase direction

– Multi-slice, multi-acquisition

– FOV, reconstruction matrix

• ON—Collects a sensitivity map during each prescan.

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PCM Wait mode—Specifies whether or not to have a wait mode beforecollecting a coil sensitivity map during the prescan. Choose from the followingoptions, as shown in the example:

• Off—Does not go to standby before collecting a coil sensitivity map.

• ON—The status changes to standby before collecting a coil sensitivity map.

PCM NSA—Sets the number of signal averages when collecting the coilsensitivity map during the prescan. The larger the value, the better the imagequality becomes; however, the prescan time is increased. The default (initialvalue) is 1, with a maximum value of 8.

Gating

The Gating section, found under the All tab of Scan Parameters, contains thefollowing parameters:

Gating—Allows you to select the type of gated scan. Choose from the followingoptions, as shown in the example:

• off—Gated scan not selected.

• MS-ECG—Electrocardiograph (pulse wave) gated scan selected.

• Cine—Cine gated scan selected.

• Resp—Respiratory gated scan selected.

The additional parameters that are available will vary with the type of gatingselected, the Sequence that is selected, and related scan parameters. In thefollowing parameter descriptions, applicable gating types are included in paren-theses after the parameter names, as shown in the example:

Example: Beat Rate (MS-ECG, Cine, Resp) indicates that the Beat Rateparameter applies to MS-ECG, Cine, and Resp gating.

Beat Rate (MS-ECG, Cine, Resp)—Enter the heart rate (in beats per minute)for MS-ECG and Cine gating. Enter the respiratory rate when Resp Gating isselected. The heart rate/respiratory rate is displayed in the WaveForm window.



# HB Prep (Cine)—Indicates the reserve heart rate prior to performing theacquisition. The Gate Mode parameter (located two parameter fields below)must be set to Delayed, as shown in the example.

Gating Source (MS-ECG, Cine, Resp)—Indicates the signal source for thegated scan. Select from the following options:

• ECG—Indicates the electrocardiograph as the signal source. ECG can beselected when the Gating parameter value is MS-ECG or Cine, as shown inthe examples.

• Pulse—Indicates the peripheral pulse as the signal source. Pulse can beselected when the Gating parameter value is MS-ECG or Cine, as shown inthe examples.

Gating is MS-ECG Gating is Cine

• Resp—Indicates respiration as the signal source. Resp is the fixed defaultwhen the Gating parameter is set to Resp.

Gate Mode (MS-ECG, Cine)—Indicates the electrocardiographic synchronousmode. Choose from the following options, as shown in the example:

• Gate—Gate method

• Trigger—Trigger method

• Delayed—Delayed enhanced method (optional)

• Myoper—Myocardial perfusion method (optional)

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Resp Mode (Resp)—Indicates the respiratory synchronous mode; the fixeddefault is Trigger, as shown in the example.

Count (MS-ECG, Cine, Resp)—Indicates the number of R-wave intervals orrespiratory cycles needed to collect the desired amount of slices. The Countvalue is dependent on the heart rate (a higher heart rate, with shorter R-Rintervals, requires an increased Count to obtain more slices). In Trigger mode,the Count setting affects the TR. The value of 1 is automatically set when theGate Mode parameter is set to Gate.

Multi Phase (Cine)—Indicates the number of images to be taken at the sameposition but at different heart phases. In the example, Gating is set to Cine andMulti Phase is set to a value of 20.

Segment (MS-ECG [with the cardiac package], Cine)—Indicates the segmentnumber. Increasing the segment number allows you more slices per R-R wave-form. You can specify this setting in the following cases, as shown in the ex-amples:

• When the Gate Mode parameter is Gate

• When the Gate Mode parameter is Trigger and the selected Sequence isBASG

Gate Mode is Gate, Segment is set to 3 Gate Mode is Trigger, Segment is set to 3



Delay Mode (Resp)—Indicates the input unit for Delay measurement. Selectfrom the following:

• Time—Sets the Delay in milliseconds (ms). The Delay represents the timefrom the trigger signal to the initial slice TE.

• Rate—Sets the Delay as a percentage (%). The Delay represents a percent-age of the breathing cycle from the trigger signal to the TE of the initial slice.

Delay (ms) (MS-ECG, Cine, Resp)—Indicates the time in milliseconds from thetrigger signal until the TE of the initially acquired slice.

Delay (%) (Resp)—Indicates a percentage of the breathing cycle as the delayfrom the trigger signal to the TE of the initial slice.

Interval (MS-ECG, Cine, Resp)—Indicates the time interval between thecollection of each slice or each phase.

Echo Alloc. (MS-ECG [with the cardiac package], Cine)—Allows you to selectthe echo allocation method. You can specify this setting in the following cases:

• When the Gate Mode parameter is Gate

• When the Gate Mode parameter is Trigger and the selected Sequence isBASG

Choose from the following options:

• Sequential—Arranges segments sequentially.

• Centric—Arranges segments centrically. This mode can be selected when theselected Sequence is BASG (2D), BASG (3D, with the Gate Mode set toTrigger), SARGE (2D), RSSG, PC, TOF, or RSSG EPI.

Following are examples showing the allocation of acquisition data for themethods.

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Echo Shift—Allows you to enter the number of echo shifts. The range isdependent on the number of segments. The example shows the implementationof echo shifts.

L level—Specifies the range for which measurement is possible during thetrigger interval (%).



Available Parameters

Beat Rate

#HB Prep

Gating SourceGate Mode

Resp ModeCount

Multi Phase

Segment

Delay Mode

Delay (ms)

Delay (%)

Interval

MS-ECG

Enter the heart rate.

Not available

Specify ECG or Pulse.Specify Trigger,Gate, Delayed, or Myoper.Not availableIndicates thenumber of R waves;1 is set if theGate Mode is set to Gate.Not available

Enter a number if theGate Mode is:• GateOR• Trigger, with a Sequence set to BASG, SARGE, or RSSGOR• Delayed, with the Sequence set to BASG (available with cardiac package)Not available

Indicates time from triggersignal to initial slice TE.Not available

Indicates scan time intervalfor each slice or phase.

Cine

Enter the heart rate.

Indicates reserve heart rate; therange is 0 to 2. Gate Mode mustbe set to Delayed.Specify ECG or Pulse.Specify Trigger, Gate,Delayed, Myoper.Not availableIndicates the number of Rwaves; 1 is set if the Gate Modeis set to Gate.Indicates the number of imagesat same position,but differing heart phases.Enter a number if theGate Mode is:• GateOR• Trigger, with a Sequence set to BASG, SARGE, or RSSGOR• Delayed, with the Sequence set to BASG

Not available

Indicates time from triggersignal to initial slice TE.Not available

Indicates scan time interval foreach slice or phase.

Resp

Enter the respiratory rate.

Not available

RespNot available

TriggerIndicates the number ofrespiratory cycles.

Not availableNot available

Select from Time (ms) orRate (%).Indicates time from triggersignal to initial slice TE.Enter rate (%) of breathingcycle from trigger signal toTE of initial slice.Indicates scan time intervalfor each slice or phase.

Summary of Gating Parameters

The following table provides a summary of the various parameters that areavailable depending on the value of the Gating parameter and scan conditions,and instructions for how the parameters should be set.

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Available Parameters

Echo Alloc.-Gate Modemust be setto Gate orTrigger(with BASGsequence)Echo Shift

L level (%)

MS-ECG

Choose from:• SequentialOR• Centric (with SARGE, RSSG, BASG, TOF, PC, or RSSG EPI) (Available with cardiac package)

Enter number (will dependon value of Segmentparameter).Specifies range for whichmeasurement is possible duringtrigger interval (%)

Cine

Choose from:• SequentialOR• Centric (with SARGE, RSSG, BASG, TOF, PC, or RSSG EPI)

Enter number (will dependon value of Segmentparameter).Specifies range for whichmeasurement is possible duringtrigger interval (%).

Resp

Not available

Not available

Specifies range for whichmeasurement is possibleduring trigger interval (%).

NAVI

The NaviPulse (navigator acquisition function) is an optional function used toreduce scanning artifacts in regions (such as the heart) where the position ismoved by breathing.

With this function, breathing movement is monitored by acquiring an additionalecho, called a navigator echo, from the region perpendicular to the diaphragm.Using the monitored change in the position of the diaphragm, scanning is per-formed with the patient “free-breathing.” The slice position can be adjustedaccording to the displacement observed from the monitored breathing movement.

The example shows how the NaviPulse function works.

Lungs Heart

Liver

Head

Feet

Acquisition position for navigator echo

This scan plane

Monitoring breath movement

Breath gating for this scan Diaphragm



The Navi section of the Scan Parameters All tab, shown in the example, containsthe following parameters:

NaviPulse—Provides the following options:

• off—Does not perform navigator acquisition.

• NaviGate—Performs navigator acquisition.

GateWindow—Indicates the gate window width in millimeters. The acquisitiondata is effective only when the position of the diaphragm is in the gate windowprescribed by this width. The default (initial value) is 3 mm.

Data Number—Indicates the number of acquisition points for the navigatordata. The selection can be 64 points, 128 points, or 256 points, as shown in theexample.

NaviMonitor—Indicates the method for the NaviMonitor acquisition during theprescan. Choose from the following options, as shown in the example:

• Auto—In cases where the monitor acquisition has been performed for thesame acquisition, the system decides if the data is usable or not. If it is usable,the acquisition will start without the performance of a monitor acquisitionduring the prescan. If it is not usable, a NaviMonitor acquisition will be per-formed.

• ON—NaviMonitor acquisition is always performed prior to an acquisition.

Monitor Time—Indicates the time for the NaviMonitor acquisition.

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PAPE

Partial Phase Encode (PAPE) is an optional function used to improve temporalresolution while maintaining the spatial resolution of the image.

The PAPE section of the Scan Parameters All tab, shown in the example,contains the following parameters:

PAPE—Provides the following options:

• off—PAPE is off.

• ON—PAPE is on.

The PAPE parameter can be set to ON when the Multi scan mode parameter isset to Dynamic or Fluoro, and the 2D/3D and Sequence fields are set to one ofthe following combinations:

• 2D and SARGE

• 2D and BASG

• 2D and TRSG

• 2D and RSSG

• 3D and RSSG

Scan Time—Displays time but is not accessible; this is the time needed toperform the acquisition, while ignoring the K-space high frequency waves.

Segment—Indicates the number of segments to be partitioned for K-space.As the number of segments increases, the scan time per image becomes shorter,but the update interval for high frequency data becomes longer. The selectionsinclude 3, 5, 7, or 9.

Data Rate—Indicates the ratio for low-frequency data that will definitely bemeasured (%). The range is from 10 % to 60%, in 5% increments.

Scan Cycle—Displays the number of cycles. This parameter is set automati-cally and remains at one number lower than the setting for the Segment param-eter. The cycle numbers available are 2, 4, 6, or 8.



Filter/PostProcessing

The Filter/PostProcessing section of the Scan Parameters All tab contains thefollowing parameters:

Org. Image—Specifies whether or not to reconstruct original images. This isavailable when the pulse sequence is set to Phase Contrast. Choose from thefollowing options, as shown in the example:

• off—Does not reconstruct original images.

• ON—Reconstructs original images.

Image Type—Specifies the type of images to be displayed. This field may beaccessible, or may be set automatically, depending on the Sequence that hasbeen selected.

The following options, as shown in the example, are available when the selectedSequence is IR or FIR:

• Abs—Displays absolute value images.

• Real—Displays Real images.

The following option, as shown in the example, is automatically set when theselected Sequence is a Shim:

• Phase—Displays Phase images.

RawData Save—Available to Hitachi Field Service Engineers. Specifieswhether or not to save the raw data to the database before image reconstruc-tion. As shown in the example, the options are:

• off—Does not save raw data to the database.

• ON—Saves raw data to the database.

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ReconMatrix—Indicates the reconstruction matrix for the image. You can set avalue larger than the frequency encoding value (from the Freq# parameter) and/or the phase encoding value (from the Phase# parameter). The example showsthe drop-down menu with available choices.

Slice#—Indicates the number of slices to be reconstructed for 3D acquisitions.You can set a value larger than the value in the S.encode (slice encode)parameter.

Slice Reject[%]—Indicates a percentage of slices at the slab ends that will notbe reconstructed. This is useful for 3D acquisitions that may have decreasedSNR at the slab ends. One half of the value that is selected is rejected fromeach end of the slab (for example, if 20% is selected, 10% of the total slab willbe rejected from each end).

Overlap[%]—Indicates a percentage amount of slab overlap, which is usedto improve the signal continuity between slab intervals in 3D TOF multi-slabacquisitions. The Multi slab parameter must have a value greater than 1.

The example shows the Slice#, Slice Reject[%], and Overlap[%] parameters setfor a 3D TOF series.

Truncation—Filtering that can be used to reduce artifacts that may appearwhen data collection conditions allow the system to acquire fewer than therequired encoding numbers (for example, low phase encoding settings of 128or 160). Choose from the following options, as shown in the example:

• off—Does not use the truncation filter.

• Auto—Automatically uses the truncation filter according to the number ofacquisition points.

• ON—Uses the truncation filter. HMSA recommends this setting for use withT2 FSE sequences.

Note:HMSA recommendsdoubling the value of the sliceencode parameter for all MRAsequences (for example, if theS.encode value is 20, the Slice#value should be 40).

Note:HMSA recommends a minimumof 30% overlap.



Shading—Filtering that corrects for signal intensity differences throughout theimage. Choose from the following, as shown in the example:

• off—Does not use the shading correction filter.

• NATURAL—Shading correction function that corrects for intensity differ-ences of the receiver coil. (A 3-D S-Map, or Sensitivity Map scan, must beperformed prior to the main scan. The S-Map data is used to compute theproper signal distribution for the receiver coil. NATURAL can then be selectedfrom the drop-down menu for the Shading parameter and applied in the mainscan.)

• Hybrid—When used with multiple images that are scanned in the sameposition (such as with Dynamic mode), the degree of correction in the firstscan is applied to later scans. When used with multiple images that are notscanned in the same position (such as 3D scans), the degree of correction iskept constant along the slice direction.

• Manual—Uses the shading correction filter. The Correction parameter(described next in this section) will be displayed.

Correction—Indicates the intensity of the shading correction. The higher thevalue, the stronger the correction will be. This parameter can be used when theShading parameter is set to Hybrid or Manual. The range is Type 1 to Type 5, asshown in the example.

Adaptive Filter—Performs filter processing for the scanned image. Provides adrop-down menu of choices, as shown in the example. For more information,refer to the “Review Task Window” section of Chapter 7, “Review and FilmingFunctions.”

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MIP Image—Specifies whether or not to create MIP images automaticallyafter the scan is finished. Choose from the following, as shown in the example:

• off—Does not create MIP images.

• ON—Creates MIP images automatically after the scan is finished.

If MIP Image is set to ON, the following parameters become available:

MIP Edge Enh.—Adjusts the quality of the MIP images that are created.The adjustment range is from –5 to 5. The image smoothness increases as itapproaches –5, and the image sharpness increases as it approaches 5.

MIP Dir—Allows you to select the view direction of MIP images from thefollowing options, as shown in the example:

• front—Creates MIP images viewed from the same direction as the directionset in the Slice Plane parameter field.

• AX—Creates MIP images viewed from the axial direction.

• COR—Creates MIP images viewed from the coronal direction.

• SAG—Creates MIP images viewed from the sagittal direction.

• SA—Creates MIP images viewed from the sagittal and axial directions.

• CA—Creates MIP images viewed from the coronal and axial directions.

• SC—Creates MIP images viewed from the sagittal and coronal directions.

• SCA—Creates MIP images viewed from the sagittal, coronal, and axialdirections.

For more infomation about MIP images, refer to the “Task MIP” section ofChapter 8, “Post-Processing Functions.”



Diffusion Analysis—Specifies whether or not to create diffusion analysisimages automatically after the scan is finished. The selected Sequence must beDW EPI or DW FSE. Choose from the following options:

• off—Does not create diffusion analysis images automatically.

• ON—Creates diffusion analysis images automatically after the scan isfinished.

If Diffusion Analysis is ON, the following fields become available:

ADC—Available when the MPG Dir# is Single or Trace. If Single is selected,the ADC field defaults to ON. If Trace is selected, the following options becomeavailable:

• off—ADC images are not created automatically after scanning.

• ON—ADC images are created automatically after scanning.

DWI trace—Available when the MPG Dir# parameter is Trace or Tensor6(optional). As shown in the example, the selections include:

• Off—DWI trace images are not created automatically after scanning.

• ON (with b0)—DWI trace images are created automatically after scanning,including b0 image.

• ON (without b0)—DWI images are created automatically after scanning,without b0 images.

Note:The b-factor value summarizesthe influence of the gradientsin DWI. The higher the b-factorvalue, the stronger the diffusionweighting. HMSA recommendsa b-factor of 1000.

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FA (Fractional Anisotropy)—(Associated with the Tensor Suite, which is apurchasable option.) Available when the MPG Dir# parameter is set to Tensor6.Calculates an index FA showing the anisotropy of diffusion from the obtaineddiffusion tensor, and creates an FA map reflecting an FA value. The selectionsare:

• Off—FA images are not created automatically after scanning.

• ON—FA images are created automatically after scanning.

MD (Mean Diffusibility)—(Associated with the Tensor Suite, which is a pur-chasable option.) Available when the MPG Dir# parameter is set to Tensor6.Calculates the mean of the intrinsic values of diffusibility and creates an imagereflecting the MD. The selections are:

• Off—MD images are not created automatically after scanning.

• ON—MD images are created automatically after scanning.

The example shows the FA and MD parameters.

Noise Threshold—Indicates a threshold value to eliminate background noise.The range is 0 to 100; increasing the value eliminates more noise.



Correct Distortion—Specifies whether or not to correct distortion of the inputimage. The selections are:

• Off—Image distortion is not corrected for the FA map, MD map, and DWITrace images.

• ON—Image distortion is corrected for the FA map, MD map, and DWITrace images.

W-Width1—Indicates the window width of the display for one echo. The setvalue becomes the default window width for displaying images. After an imageis displayed, the window width can be changed.

W-Level1—Indicates the window level of the display for one echo. The setvalue becomes the default window level for displaying images. After an image isdisplayed, the window level can be changed.

W-Width2—Available when the Multi Echo parameter (in the Seq. Parameterarea) is set to 2 or greater. Indicates the window width of the display for twoechoes. The set value becomes the default window width for displaying images.After an image is displayed, the window width can be changed.

W-Level2—Available when the Multi Echo parameter (in the Seq. Parameterarea) is set to 2 or greater. Indicates the window level of the display for twoechoes. The set value becomes the default window level for displaying images.After an image is displayed, the window level can be changed.

The example shows the window width and level parameters.

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Positioning

Positioning parameters allow you to select various options involved with thescanning and viewing of images. The Positioning section, found under theAll tab of Scan Parameters and shown in the example, contains the followingparameters:

Slice Ord. A—Specifies the direction in which the axial plane slices will bescanned and displayed. Choose from the following options, as shown in theexample:

• H-F—From head to feet

• F-H—From feet to head

Slice Ord. S—Specifies the direction in which the sagittal plane slices will bescanned and displayed. Choose from the following options, as shown in theexample:

• R-L—From right to left

• L-R—From left to right

Slice Ord. C—Specifies the direction in which the coronal plane slices will bescanned and displayed. Choose from the following options, as shown in theexample:

• A-P—From anterior to posterior

• P-A—From posterior to anterior



Plane Order—Displays the scanning order of the slice planes when multipleplanes have been selected in the Sequence area. This field is for display only;the plane order cannot be changed, but the slice order within a plane can bechanged.

The following options are available:

• AX—Axial plane

• SAG—Sagittal plane

• COR—Coronal plane

• S-A—Sagittal plane, axial plane

• S-C—Sagittal plane, coronal plane

• C-A—Coronal plane, axial plane

• S-C-A—Sagittal plane, coronal plane, axial plane

The example shows a Plane Order of S-A.

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Slice Allocation—Indicates the order of slice excitation for multi-slice scanning.This parameter is available with the following parameter settings:

• 2D/ 3D—Set to 2D.

• Sequence—Set to GE, SARGE, or RSSG.

• Multi Acquisition Mode—Set to Interleaved.

As shown in the example, the slice allocation selections include:

• Default—Scans from one side of the slices to the other side.

• Convergence—Scans from both sides of the slices towards the center.

Line/Box—Specifies the manner in which the slice lines will appear when theyare displayed in the viewports for positioning. This selection cannot be made for3D acquisitions. The following choices are available, as shown in the example:

• Line—Displays the slice surface as a line.

• Box—Displays the slice surface as a box.



Guide Line—Specifies whether or not guidelines will appear when changingslice position or number of slices. Guidelines are the dotted lines displayed at thetop and bottom of the slice group. The following options are available:

• Yes—The dotted lines are longer than the slice lines and continue to bedisplayed when slices are moved. The example shows the Guide Lineparameter set to Yes. The top viewports show the guidelines being displayed.

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• No—The dotted lines are approximately the same length as the slice linesand are displayed around the outer edges of the slice group. They will not bedisplayed during slice movement and will not be displayed as a midline slice.The example shows the Guide Line parameter set to No. The top viewportsshow that the guidelines are not being displayed.



G.Intvl—Specifies whether or not the slice interval can be changed for eachslice stack or slab group for scans that involve multiple stacks or slabs. Thefollowing options are available, as shown in the example:

• off—The slice interval for each slice or slab group can be changed. When offis selected, the Interval field will be displayed in the Scan Positioning bar at thebottom of the viewports. The example shows the G.Intvl parameter set to off.

• ON—The slice intervals for each slice or slab group are set to the same valueand cannot be changed individually. When ON is selected, the Interval fieldwill be displayed in the Seq. Parameter area. The example shows the G.Intvlparameter set to ON.

Sync.—Specifies whether to simultaneously change all plane settings when thesettings for position, angle, and slice number are changed, and multiple planeshave been selected. This function is enabled only when the Slice Planeparameter is SA, SC, CA, or SCA. Choose from the following options, asshown in the example:

• off—Does not change the settings of all planes.

• ON—Changes the settings of all planes.

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Others

The Others section, found under the All tab of Scan Parameters, contains thefollowing parameters:

Receiver Coil—Select the receiver coil name from the drop-down list ofconnectable receiver coils, as shown in the example. If set to Auto, the receivercoil name is recognized automatically.

Mode—Specifies the receiver coil mode for multi-mode coils, such as the CTLand Neurovascular coils. A selection can be made from the drop-down list ofmodes that are available for the receiver coil that has been chosen, as shown inthe examples.

Mode option examples

If the Receiver Coil field is set to Auto, the Mode field will change to Default, asshown in the example. The system will set the most common mode for thereceiver coil that is being used.



MorningQA—Specifies checks to be performed during the morning qualityassurance (QA) procedures. When starting the system, scanning is performedwith fixed parameters to confirm that the system is operating correctly. Allparameters that are currently set are disabled, and the fixed parameters are set.Choose from the following options, as shown in the example:

• off—Does not perform MorningQA.

• GC Check – FID—Acquires the FID (free induction decay) signal.

• GC Check – X—Checks X-axis gradient movement.

• GC Check – Y—Checks Y-axis gradient movement.

• GC Check – Z—Checks Z-axis gradient movement.

• Coil Check—Checks each channel of the coil.

Silent—Specifies silent mode, which decreases the noise level for certainpulse sequences. Activation of the silent mode requires an increase in TR, and,consequently, an increase in scan time. Choose from the following options, asshown in the example:

• off—Acquisition is not performed with the silent mode.

• ON—Acquisition is performed with the silent mode.

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Additional Functions

The following functions can be initiated using parameters found in the variousgroups of the Scan Parameters area.

NATURAL (NATural Uniformity Realization ALgorithm)

NATURAL is an intensity correction function. It corrects for the differentiationsin the sensitivity of the receiver coil, which can result in shading. Generally, coilswith more channels exhibit more shading; additionally, coils with smaller diam-eters exhibit greater sensitivity.

A 3D S-Map scan must be performed using the transmit-receive body coil(which is built into the system) and the receiver coil that is to be used during themain scan. The data from both coils is averaged and then used to compute theproper signal distribution, or shading correction, for the coil. Images are notproduced from the S-Map sequence, but coil intensity should be corrected inthe main scan.

The correct order of sequences when using NATURAL is as follows, as shownin the example:

1. Scanogram

2. Shim (if needed for the main scan sequence)

3. S-Map

4. Main scan; NATURAL should be selected in the Shading field in theFilter/Post Processing area, as shown in the example.

Order of tasks

Setting of Shading parameter



Additional considerations for the S-Map sequence include the following:

• This sequence is very sensitive to patient movement. Breathholds must beused if performed in the abdominal area. When Wait Mode is ON, the systemwill pause after the prescan, as well as in the middle of the S-Map scan.Results may be improved if the breathholds are performed on expiration.

• The FOV for the S-Map should be 20% to 30% larger than the FOV that willbe used in the main scan.

• The S-Map sequence should be performed in the plane where you are leastlikely to encounter aliasing artifacts.

The NATURAL function cannot be used with the following:

• The quad head coil

• The transmit/receive body coil (by itself)

• Slice plane parameter values of SA, CA, SC, SCA

• The measurement functions, including shimming, phase-contrast angiography,spectroscopy, interactive scan control (ISC), and fluoroscopy

6Scan Parameters

QS4-36980v1 6 - 83

TIGRE

The TIGRE sequence is a 3D fast, T1-weighted, RF-spoiled SARGE sequenceusing a fatsat pulse. This sequence can be used for T1-weighted fat-suppresseddynamic imaging with contrast. A segmented fatsat pulse is used to maintain fatsuppression and provide sufficient temporal resolution for dynamic scans.Shimming must be performed before the TIGRE acquisition.

The specific parameter selections that are required or recommended for TIGREare described below.

Sequence AreaSelect the following:

• 2D/3D—Select 3D.

• Sequence—Select RSSG.

Seq. Parameter AreaFor Echo Alloc., select one of the following, as shown in the example:

• Cent-Cent—Echo allocation for phase encode and slice encode directions areboth Centric. The value entered in the #RF Prep field should be increased (ascompared to the value used for Cent-Seq) to suppress artifacts, even thoughthis reduces the effects of fat suppression.

• Cent-Seq—Echo allocation for the phase encode direction is Centric, whileecho allocation for the slice encode direction is Sequential.

Advanced AreaFor the #RF Prep parameter, HMSA recommends using a value of about 5 withCent-Seq echo allocation, and a higher value for Cent-Cent allocation. This valuerepresents the number of dummy RF pulses needed to maintain the steady stateafter the application of the segmented fatsat pulse. Larger numbers may improveartifact suppression but also reduce the effect of fat suppression.

Saturation AreaSelect the following, as shown in the example:

• Saturation—Select Segment FS.

• Wave—Select H-Sinc.

• RF amp (%)—Enter 100.

• Segment—HMSA recommends a value of about 32.

Note:HMSA recommends the use ofCent-Seq as the Echo Alloc. forall TIGRE acquisitions.



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