Radiology Lecture - 02

8/9/2019 Radiology Lecture - 02

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Who is it?

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1the dog2 the cat

What is the name for this Image?

1. Plain film of the pelvis

2. Computed axial Tomogramm of the chest

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1. Magnetic Resonance Tomogram of the chest

2. Computed axial Tomogramm of the chest

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1. Sonogram of the head

2. Magnetic Resonance Tomogram of the head

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1. Liver Sonogram

2. Liver MRI

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1. Bone radionuclide image

2. The hole body MRI

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1. Radionuclide imaging

2. MRI

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Which of techniques uses Ionizing

radiation?

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1. Roentgenogrphy

2. Ultrasound imaging

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Which of imaging techniques cant

cause damage to human?

1. Roentgen tube

2. Radiopharmaceutical agent in human body

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What is the source of radiation in X rayexamination?


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Roentgen tube is source of

radiation in X ray examination

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1. The human body itself

2. Radiopharmaceutical agent in human body

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What is the source of radiation inradionuclide examination?

Nuclear Medicine Imaging

Radioactive isotopes concentrated in certain tissues emit

gamma radiation, that is a source of radiation in

radionuclide imaging.14


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1. The human body itself

2. Roentgen tube

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What is the source of radiation inthermography?

Infrared Imaging or Thermography

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1. Lateral view

2. Direct view

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What is the name for this roentgenogramprojection?

1. Lateral view

2. AP or direct view

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What is the name for projection of this emissionradionuclide image of abdomen ?


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1. Panoramic

2. Tomographic

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Is it panoramic or tomographic radionuclideimage of abdomen ?

1. Panoramic

2. Tomographic

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1. this is vertebral artery angiogram,

panoramic lateral view

Is it panoramic or tomographic image of head?


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The planes of section define three ways to slice' the

body as follows:

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Z

x

y


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Transverse (X-Y)

Transverse (or axial) sections

form a series of

circumferential slices - rather

like slicing the body into a

series of pancakes and

stacking them atop one

another.

In the transverse (or axial)

plane, where right and left

should go depends on if we

are looking from the head

down or the feet up.

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Coronal (X-Z)

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Coronal sections follow front to back, as though cutting through a corona,

or halo, around the head.


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Sagittal (Y-Z)

Sagittal sections

follow from one side

of the body to the

other - left to right, or

right to left

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Is this image illustrate spatial or contrast

resolution?

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1. Spatial

2. Contrast

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What square illustrates the best resolution?

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1. first

2. third 2

1

2

3

What square illustrates the best contrast

resolution?

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1. first

2. third 1

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Two projections (views)

31 Lateral PA

1. As the two units (tube (T) and film

(F) move horizontally,

simultaneously, only body

structures that lie in a specific

geometric plane will allow X- rays

to consistently pass through to the

detector.

2. In this way, those structures that

lie in a specific geometric plane

show up clearly on the film, while

structures outside the plane are

blurred.

3. The image produced by this type

of radiology is parallel to the long

1. As the two units (tube (T) and film

(F) move horizontally,

simultaneously, only body

structures that lie in a specific

geometric plane will allow X- rays

to consistently pass through to the

detector.

2. In this way, those structures that

lie in a specific geometric plane

show up clearly on the film, while

structures outside the plane are

blurred.

3. The image produced by this type

of radiology is parallel to the long

Conventional tomography

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film

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Blurred undesirable slices present in tomogram

as unclear gray shadows lines that are parallel

to the long axis of image34

At lateral plane film enlarged aerated sinus sphenoidalis with

thin bony walls superimposed by other bony structures of face

skeleton

conventional tomogram clarify the image making the

diagnosis easy - Pneumocele of sinus sphenoidalis35

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Conventional tomography of the chest

Tumor of right main bronchus

Tomographic motion minimizes

x-ray intensity fluctuations in

the bones shadows, thereby

increasing both contrast and

overall visibility of the desired

image.

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Conventional Radiography (CR )

Also called plain films or standard films, X-ray,

CR can produced real time imaging to watch moving

structures that called fluorography

Image forms using broad beam ionizing radiation (X rays)!

T

he image formation is related to the subject density! CR may involve the use of contrast agents!

The use of contrast agents in combine with fluorography is the

GE radiology imaging

To improve image contrast to remove superimposition effect

CR may involve conventional tomography technique!

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Advantages

Cheap

Rapid

Panoramic view

Good spatial

resolution

Disadvantages

Ionizing radiation

Superimposition-

summation of

shadows

Bad contrast

resolution

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Computerized Tomography (CT)

Computed axial tomography has been one of the biggestbreakthroughs in diagnostic radiology.

The first clinical CT scanner was developed by G.N. Hounsfieldfor examination of head and was installed in 1974 at AtkinsonMorleys hospital in Wimbledon, England.

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CT scanner for examination of head installed in

1974 at Atkinson Morleys hospital in Wimbledon,

England

Copyright Oleh Tretiak, 2004 40

Computed axial

tomography The first body CT scanner

was installed in 1974 and

before the end of 1970s the

basic technical evolution of

CT was complete.

Technical details were

refined during 1980s and CT

technology remained on aplateau until early 1990s

when the advent of spiral

(helical) CT scanning made a

further rapid evolution

leading to improve

diagnostic capability, 3 D

imaging techniques and CT

angiography.41

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Helical CT

Computed spiral

tomography

3D reconstruction

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Computed spiral tomography

angiography

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Computed multi slice tomography

The latest innovation is the

introduction of multi slice CT

in 1998.

This new technology is vastly

expended the performanceof CT scanners.

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Computed multislice

tomography

It truly transforms CT from a

transaxial imaging modality

to a 3 D technique that

yields high quality images in

arbitrary planes and forms

the basis for an expending

variety of 3 D visualisation

technique including virtual

endoscopy.

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CT Bronchoscopy

Path View

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CT Colonoscopy

Path View

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Comparison

Left:A polyp seen with optical endoscopy.

Right: View in vir tual endoscopy.

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Computer Tomography:

How It Works

The images are produced by rotating the x-ray tube and

detectors around the patient in a circle.

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How It Works

X-ray beam passes through a thin axial section

of patient from various directions.

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How It Works

Parallel collimation is used to

shape the x ray beam to a thin

fan which define the thickness

of the scan plan

Fan-Beam Computer Tomography

Detectors measures the

intensity of attenuated

radiation as it emerges

from the body.

Detectors

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A mathematical image reconstruction (inverse Radon

transformation) calculates the local attenuation at each point

within the CT section.

These local attenuation coefficient translated into CT numbers

and are finally into shades of gray that are displayed as inimage.

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The computer then runs a series of complex algorithms

to reconstruct the image, which can then be displayed

on a monitor. 55

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Computed axial tomography (CAT)

Unlike conventional tomography, the image produced by

computerized transaxial tomography is a cross section of thebody and is called a transaxial image because it is perpendicular

to the body's long axis


How It Works

A CT image is composed of a square

image matrix that ranges in size from

256x 256 to 1024x1024 picture element

or pixels.

Every pixel has his one attenuation

number or density of according body

slice point.

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5858

These CT numbers are translated intoshades of gray that are displayed as inimage on monitor.

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Human eye can distinguish only a limited number of gray

levels (16-100).

The complete diagnostic range of CT numbers is 4000.

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So there is no point in assigning

the complete diagnostic range of

numbers to the available range of

gray levels (from white to black)

because discrimination between

structures with small differences

in CT number would no longer

possible.

It is there for better to display just

a portion of CT scale. This so called

window is defined by its width

which affect image contrast and byits level (centre) which determines

image brightness.

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Example of Contrast

12 bit image, full

contrast range.

Window for low

densities

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More Contrast Operations

Window for high

densities_

Soft tissues window

CompareLung window Soft tissues window

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Compare

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At hard copy (film) you cant change the window

and have to read it complete!!!

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Advantages CAT Over ProjectionRadiography

AdvantagesOnly thin tissue slices are exposed to X -rays.

There is no disturbing superimposition or blurring ofstructures located outside the selected tissue planes as inconventional tomography.

The result is a good contrast resolution far superior toconventional X -ray techniques.

There is no disturbing superimposition or blurring ofstructures located outside the selected tissue planes as in

conventional tomography

The small tumor in the right lung onplain film

The same tumor on CAT imaging

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The result is a good contrast resolution farsuperior to conventional X -ray techniques

Give a visualization of differences between tissues that

differ in physical density by less than 1%.

CAT is the best method for evaluation of renal stone

The Advantages

Over Projection

Radiography Data from a single CT

imaging procedure

consisting of either

multiple contiguous or one

helical scan can be viewed

as images in the axial (A),

coronal (C), or sagittal (S)

planes, depending on the

diagnostic task in programsof multiplanar

reconstruction

A

C S

V

The images of patient with

Aneurism of abdominal aorta with dissection

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The Advantages Over Projection

Radiography

Data from a single CT

imaging procedure

consisting of either

multiple contiguous

or one helical scan

can be viewed as

images in volume

rendering model (V).

A

C

V

Special terms used on CT reports:

Low density

High density

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In conventional roentgenlogy to make some

organ to be visible we use contrast agents

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Barium sulfate meal per os in

upper GE series

Barium sulfate emulsion in enema

in low GE series

Intravenously IODINE (J2) contrast agents to

make be visible parenchyma and vessels ore

only vessels

73pyelography angiography

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Native CAT images of abdomen

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intravenously IODINE contras medium have done

intravenously IODINE contras medium have done

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Contrast media intravenously and per oral

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Contrast for CT

Iodine injected into an arm vein during the scan

Iodine or Barium diluted in water given orally

for abdomen scans

Enhances the blood vessels and organs andmakes them much easier to see

Enhances cancerous tissue in many cases

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CAT images of the liver in

different step of contrast exam

5% of thepatient have a

mild ore severereaction toiodine contrastagent!!!

There are some risks

Allergic reaction

Kidney damage

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Diagnostic use of CAT:

Cranial CT

Diagnosis ofcerebrovascularaccidents andintracranialhemorrhage is themost frequentreason for a "headCT" or "CT brain".

Epidural hemorrhage

Cranial CT

CT generally does notexclude infarct in theacute stage of a stroke,but is useful to excludea bleed soanticoagulantmedication can becommenced safelyonly after CAT ofcranium

Hemorrhage in left hemisphere of

brain

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Cranial CT

For detection of brain

tumors, CT scanning

with IV contrast is

occasionally used

but is less sensitive

than magnetic

resonance imaging

(MRI).

Meningioma on postcontrast CAT of

head

Cranial CT also be used

to detect increases in intracranialpressure,

for evaluat ing facial and skull

fractures,

for surgical planning for

craniofacial and dentofacial

deformities,

evaluation of cysts and some

tumors of the jaws/sinuses/nasal

cavity/orbits,

diagnosis of the causes of chronic sinusitus,

for planning of dental implantreconstruction.

Volume rendering of CAT scan

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Chest CT

CT is excellent:

For detecting both acute and

chronic changes in the lung

parenchyma,

For detection of airspace

disease (such as pneumonia

or cancer).

Ordinary non-contrast scans

are adequate.

Pneumonic infiltration in low right

lobe

Chest CT

CT is excellent:

For evaluation of chronic

interstitial processes

(emphysema, fibrosis).

Thin (0.5-2 mm) sections

with high spatial frequency

reconstructions are used.

Diffuse emphysema

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Chest CT

For evaluation of the

mediastinum and hilar

regions for

lymphoadenopathy.

In this cases we need IV

contrast administration!!!

Mediastinal lymph node hyperplasiaCT is used:

MSHCT in acute chest pain/ dyspnea

CT angiography of the chest

Becoming the primary

method for detecting

pulmonary embolism (PE)

and aortic dissection.

Rquires accurately timed

rapid injections of contrast

and high-speed helical

scanners!!!

PE

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CT is the standard method of evaluating abnormalities seenon chest film and of following findings of uncertain acute

significance

High density shadow on PA plainfilm of chest Tumor nodule on CT image

Abdominal and pelvic CT

The most common uses diagnosisof

Renal or urinary stones,

Appendicitis,

Pancreatitis,

Diverticulitis, Abdominal aortic aneurysm,

Bowel obstruction.

Abdominal aortic aneurysm,

postcontrast CT

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Abdominal and pelvic CT

Renal stones.

Appendicitis the appendix lies behind the

caecum and has a light thickened wall incontrast image.

There is the stone in appendix (arrow).

Abdominal CT

Acute pancreatitis.

Axial contrast-enhanced CT scan

shows fluid collection in

peripancreatic space and minimal

necrosis of pancreas parenchyma

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CT is also the first line for detecting solidorgan injury after trauma

CT shows a subcapsular hematomawith a splenic laceration extending

from the capsule to the hilum with

an intraparenchymal hematoma

(blue arrow).

Deep laceration with a largeperinephric haemorrhage withhaemorrhagic extension intoposterior pararenal space.

The usefulness of contrast

administration

Renal abscess after contrastadministration

Renal abscess without contrast

administration

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In most cases it is necessary intravenous contrast

administration

Liver tumor after contrastadministration

Liver tumor without contrast

administration

Extremities

CT is often used to image complex fractures, especially ones around

joints, because of the ability to reconstruct the area of interest in

multiple planes.

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Computed Axial TomographyComputed Axial Tomography

Also called CAT scanning or CTAlso called CAT scanning or CT

Image formed using a rotating thin beams ofImage formed using a rotating thin beams ofionizing radiationionizing radiation

Image slices reconstructed by computationImage slices reconstructed by computation

The image formed is related to the subjectsThe image formed is related to the subjectsdensitydensity

Image display on computer or multiple filmsImage display on computer or multiple films

Advantages

Eliminates the

superimposition of

images of structuresRather rapid

Good contrast

resolution

Disadvantages

Ionizing radiation

Expensive

Computed Axial TomographyComputed Axial Tomography

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Some cool things we can do with

CT these days CTAngiography - Scan rapidly during Iodine

injection in vein

Colonography - Scan colon after filling with air

Bronchoscopy - Scan chest air is already in bronchi

3D Images Computer reconstruction

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Femoral arteries

Aorta

Iliac arteries

CT Angiography

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mages ompu er


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mages ompu er

reconstruction

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CT Bronchoscopy

Path View

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Path View

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Colonoscopy

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Colonoscopy

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Documents

Radiology Lecture - 02