Endovascular vs. Invasive Neuro -vascular Interventions · 3. X-ray image guidance vs. visual ... Ionita CN, Chang C, Sinelnikov A, Bednarek DR, ... SPIE vol. 6142 , pp. 6142R1 -11,

New High Resolution Dynamic Detectors and Flow Modifying Stents

for Neuro-Endovascular Image Guided Interventions (EIGI)

S Rudin, CN Ionita, A Kuhls-Gilcrist, C Keleshis, W Wang, DR Bednarek

(Supported by NIH grants R01 EB002873, NS43924, and EB00842501;

UB Fnd. IRDF and a Toshiba Med. Sys. Corp. equipment grant)

Endovascular vs. InvasiveNeuro-vascular Interventions

1. Arterial puncture vs. larger dissection of body cavity or skull

2. Use of catheter vs. scalpel, drills, clamps, etc.

3. X-ray image guidance vs. visual viewing

Advances in EIGIs Devices and Detectors*• Devices

– Catheters and stents– Clot busters– Flow modifying asymmetric vascular stents (AVS) for aneurysms

• Stainless, balloon expandable, open cell, steel mesh flow modifier• Stainless, baloon expandable, open cell, polyurethane film modifier• Nitinol, self-expanding, open cell, polyurethane film flow modifier• Nitinol, self-expanding, closed cell, PTFE porous film flow modifier

• High Resolution Detectors– Micro-angiographic (MA) detector– Micro-angiographic Fluoroscope (MAF)– Solid State X-ray Image Intensifier (SSXII)

• New Imaging System Evaluation Concepts– MTF only from noise response measurements– Instrumentation Noise Equivalent Exposure and Quantum

Limited Performance– GMTF and GDQE

*Rudin S, Bednarek DR, Hoffmann KR: Endovascular Image Guided Interventions (EIGI).Vision 20/20 paper. Medical Physics 35(1): 301-309, Jan 2008.



• Stainless, balloon expandable, open cell, steel mesh flow modifier• Stainless, balloon expandable, open cell, polyurethane film modifier• Nitinol, self-expanding, open cell, polyurethane film flow modifier• Nitinol, self-expanding, closed cell, PTFE porous film flow modifier





Catheters

guiding catheter introducer

microcatheters

flexible

Balloons

Stent on balloon

Stents (on Balloon)

Stenotic vessel with plaque.Stents: drug eluting or bare; covered or not;

material: stainless steel, nitinol, dissolvable(?)expand: balloon or self

Various lengths and diameters

Tetra (Guidant)

Velocity (Cordis)

Stents

1. Integra, nitinol self-expanding (J and J)

2. Multilink, stainless steel, balloon expanding (Guidant)

3. Needle, 26 Ga4. Wallstent, stainless

steel, self-expanding (Boston Scientific)

1

2

3

4

ECOSMicroLysUS

Neurojet

LaTis laser

G. M. Nesbit et al: JVIR 2004; 15:S103–S110

Clot Busting

InTime Retriever and Ensnare

Merci Retriever

Neuronet

Clot Removal Advances in EIGIs Devices and Detectors*• Devices


• Stainless, balloon expandable, open cell, steel mesh flow modifier• Stainless, balloon expandable, open cell, polyurethane film modifier• Nitinol, self-expanding, open cell, PTFE porous film flow modifier• Nitinol, self-expanding, closed cell, PTFE porous film flow modifier





Flow Modification: Treatment of intracranial aneurysms using asymmetric stents

Perforators (50-200 µm)

Asymmetric Stent in 2-3 mm vessel

C. Ionita

Flow Modifying Stent for Aneurysm Treatment

C. Ionita, et al

Pre-stent Post-stent

Use of 3D forComputational Fluid Dynamics (CFD)

Treatment Planning

Obtain 3D model (vessel or aneurysm)

Create a mathematical grid

Solve the differential equations(Navier-Stokes equations)at each grid pointat each time point

Asymmetric Stent Altering Aneurysm Flow

Untreated StentedStreamlines

Untreated StentedWall Shear Stress

WSS(dyne/cm2)

Untreated Stented

Velocities








Flow Modifying Asymmetric Vascular Stents (AVS)

C. Ionita, et al

Balloon expandableStainless steel stentStainless steel mesh flow modifierOpen cell

Balloon expandableStainless steel stentPolyurethane film flow modifierOpen cell

Self expandingNitinol stentsPTFE film flow modifier

Open Cell

Closed Cell

Asymmetric Vascular Stents (AVS)

Ionita CN, Chang C, Sinelnikov A, Bednarek DR, Rudin S: Angiographic analysis of aneurysms treated witha novel self-expanding asymmetric vascular stents (SAVS) (abstract). Medical Physics, June 2009, WE-C-304A-5.

Stent designs such as Enterprise and Wingspan

Clo

sed

Cel

l

Ope

n C

ell








Region of Interest (ROI) Micro-angiography and Fluoroscopy for Image-guided

Interventions (IGI)

Detector requirements:� Angiography, ROI-CT, and new device imaging:

• High resolution (> 4 Lp/mm)� Real-time fluoroscopy for image guidance:

• High sensitivity - low instrumentation noise (quantum noise limited)• High speed (30 fps)• No lag (high temporal resolution)

� ROI imaging: reduce integral radiation dose

Detectors:� High Sensitivity Micro-Angiographic Fluoroscope, MAF� Solid State X-ray Image Intensifier, SSXII

New High Resolution Detectors• Micro-angiographic detector, MA (not fluoro capable )• High Sensitivity Micro-angiographic Fluoroscope,

MAF (with light amplifier for gain)• Solid State X-ray Image Intensifier, SSXII

(built-in EMCCD gain, fluoro capable)

FOT

FOP

FOP

CCD Camera

CsI

MA detector (no gain) MAF detector

FOP

FOP

FOPs

Gen2 LA withMCPs

CCD Camera

CsI

Photocathode

FOTFOT

FOP

FOP

EMCCD Camera

CsI

SSXII detector




FOT

FOP

FOP

CCD Camera

CsI


FOP

FOP

FOPs

Gen2 LA withMCPs

CCD Camera

CsI

Photocathode

FOTFOT

FOP

FOP

EMCCD Camera

CsI

SSXII detector

The High-Sensitivity Microangiographic Fluoroscopic (MAF) Detector

� High sensitivity for fluoroscopic applications

• Direct fiber-optic coupling (no lenses): Fiber-optic plate (FOP) windows, Fiber-optic taper (FOT)

• LII (LA) with MCPs for variable high system gain

� High resolution (~ 35 µm pixel in equal-area-framing)

MCP LII

CsI(Tl)

CCD Camera

FOT

FOP

FOP

FOP

MCP LII

CsI(Tl)

CCD Camera

FOT

FOP

FOP

FOP

CCD CameraCCD CameraCCD Camera

FOT

FOP

FOP

FOP LIICCD Camera

FOT

Power Supply for the LII

Ionita CN, Keleshis C, Jain A, Bednarek DR, Rudin S: Testing of the high-resolution ROI micro-angio fluoroscope (MAF) detector using a modified NEMA XR-21 phantom (abstract). Medical Physics, June 2009, MO-FF-A4-3.Jain A, Bednarek DR, Rudin S: Performance evaluation of a custom-made anti-scatter grid used for the high-resolution Micro-Angiographic Fluoroscope (MAF) (abstract). Medical Physics, June 2009, WE-C-304A-3.

Line-Pair Phantom

MAF and FPD Detectors

Wang W, Keleshis C, Kuhls-Gilcrist A, Ionita CN, Jain A, Bednarek DR, RudinS: New High-Resolution-Detector Changer for a Clinical Fluoroscopic C-Arm Unit (abstract). Medical Physics, June 2009, SU-FF-I-171

High Resolution ROI Detector Implementation

DeployedRetracted

Roadmaps of AVS treated-AneurysmsMAF XII

Un-

depl

oyed

Dep

loye

d




FOT

FOP

FOP

CCD Camera

CsI


FOP

FOP

FOPs

Gen2 LA withMCPs

CCD Camera

CsI

Photocathode

FOTFOT

FOP

FOP

EMCCD Camera

CsI

SSXII detector

Imaging Imaging AreaArea

FrameFrame

Serial Serial RegisterRegister

MultiplicationMultiplicationRegisterRegister

Transfer AreaTransfer AreaOutputOutput

AmplifierAmplifier

Electron Multiplying CCD

( ) xGain 2000019.1 400 ≈=

( ) xGain 10006.1 400 ≈=22 V

15 V

Current State-of-the-ArtSSXIIAcquisition Parameters: 70kVp; 160mA; 45ms; 2” PMMA; 0.3mm Focal Spot; Identical Geometry

High-Resolution Imaging

Kuhls-Gilcrist A, Bednarek DR, Rudin S: Component analysis of a new solid state x-ray image intensifier (SSXII) using photon transfer. SPIE vol. 7258, 2009. In: Proc. from Med. Imaging 2009: Physics of Med. Imaging, Orlando, FL, # 7258-42, 725817:1-10.

Initial Images: Asymmetric Stent

Kuhls AT, Yadava G, Rudin S: Progress in electron-multiplying CCD (EMCCD) based, high-resolution, high-sensitivity x-raydetector for fluoroscopy and radiography. SPIE 6510-47, 2007. In: Proc. Med. Imag. 2007: Phys. of Med. Imag., San Diego, CA.

Kuhls-Gilcrist AT, Yadava GK, Patel V, Bednarek DR, Rudin S: The Solid-State X-Ray Image Intensifier (SSXII): AnEMCCD-Based X-Ray Detector. SPIE 6913-19, 2008. In: Proc. Med. Imag. 2008: Phys. of Med. Imag., San Diego, CA.

SSXII XII

3.3 mR

90 µR

100 µm Au

50 µm Pt

100 µm I

AVS w, polyUPatch marked

Detector Mosaic Array(Extended FOV)

Rudin S, Yadava G, Josan G, Kuhls A, Rangwala H, Wu Y, Ionita C, Bednarek DR: New light-amplifier-baseddetector designs for high spatial resolution and high sensitivity CBCT mammography. SPIE vol. 6142,pp. 6142R1-11, 2006. In: Proc. Med. Imag. 2006: Phys. of Med. Imag., San Diego, CA, paper #63.

Wang W, Keleshis C, Kuhls-Gilcrist A, Bednarek DR, Hoffmann KR, Rudin S: Control, Acquisition, Processing, and Image Display System (CAPIDS) for the Solid-State X-Ray Image Intensifier (SSXII) (abstract). Medical Physics, June 2009, SU-FF-I-170.

Control, Acquisition, Processing, and Image Display System

(CAPIDS)

Control, Acquisition, Processing, and Image Display System(CAPIDS)










Errors in Conventional Slit Method

(Simulation)

Slit Width

Slit Angle

3 % Added Noise

Jain A, Patel V, Kuhls-Gilcrist A, Bednarek DR, Hoffmann KR, Rudin S:Effect of point spread function, x-ray quantum noise, and additiveinstrumentation noise on the accuracy of the angulated slit method fordetermination of pre-sampled detector MTF. (abstract).Medical Physics, June 2009, SU-FF-I-108.















• GOAL: Provide a Simple and Accurate Presampled MTF Measurement Technique for Digital Radiography Systems

• Use only the Detector Noise Response

• Inherently 2-D

Line Spread Function

Noise Response Method

Kuhls-Gilcrist A, Jain A, Bednarek DR, Rudin S: A method for measuring the MTF of digital radiography systems using noise response (abstract). Medical Physics, June 2009, WE-C-304A-7.

Cascaded Linear Systems: Results

Output NPS:

( ) ( )[ ] ( )vuNPSygxvuTvuAgyxvuNPS ADDSYSS , ,,~),( 4421 +Φ∆∆+∆∆= −

(((( ))))(((( ))))(((( ))))

signaloutput

factor conversionnumber digital-to-electron

noise electronic additive,

factorSwank dependent -frequency,

MTF presampled,

ray)- xabsorbedper (DNgain system ~ widthpixel ,

4

4

============================

Φ

∆∆

g

vuNPS

vuA

vuT

g

yx

ADD

S

SYS


Output NPS:


Primary Quantum + Poisson Excess Noise

Secondary Quantum Noise

Additive Noise Primary Quantum + Poisson Excess Noise


Output NPS:


Secondary Quantum Noise

Additive Noise

Presampled MTF is Inherently in the Noise

Response!

Image Simulations: Simple Detector Model

• 1000 x 1000, 32 µm Pixels

• 150 µm CsI Phosphor

• “True” MTF Known Exactly

NR Method: Procedure• Acquire 30 Flat-Field Images at Several mAs

Values [IEC Guidelines; Standardized Spectrum (RQA)]

• Measure NPS(u, v)




• Plot NPS(u, v) versus Signal and Fit with 2nd Order Poly.




• Plot NPS(u, v) versus Signal and Fit with 2nd Order Poly.

• Fit Quantum NPS (Slope Data)( ) ( )( )

5

2

4

23

21

MixtureGuassian expF hh

hfh

fA

hf

S

+

−−=

Presampled MTF

NR Method: ResultsAveraged

Deviation = 0.3%

NR Method: ResultsER Averaged

Deviation > 30%








Detector Noise Evaluation: Instrumentation Noise Equivalent

Exposure (INEE) Model*

Nexp2 = k ( E + INEE )

IF E>INEE, then quantum noise limited.IF E<INEE, then instrumentation noise limited.

*Kuhls-Gilcrist A, Bednarek DR, Rudin S: The Instrumentation Noise Equivalent Exposure (INEE): Including conversion, secondary quantum, structure and electronic noise (abstract). Medical Physics, June 2009, WE-C-304A-8.

Noise Versus Exposure

INEE = 2.0 µR

INEE

InstrumentationNoise Limited

QuantumNoise

Limited

Instrumentation Noise Limited?

Quantum Noise Limited

Instrumentation Noise Limited








Phantom: Scattering fraction, ρ

MAF Detector, D

X-ray tubeFocal spot, F

Patient Table

Factors affecting GMTF and GDQE for given object plane:detectorscattering objectfocal spot

Image mag, m

)()()1

()1(),,(m

fMTF

m

fMTFf

m

mMTFmfGMTF DSF

+−−= ρρρ

� Generalized Modulation Transfer Function (GMTF)

� Generalized Noise Power Spectrum (GNPS)

222

),(

)(

),(),,(

m

Xm

fNNPS

Xdm

Xm

fNPS

mXfGNNPSDD

==

� Generalized Noise Equivalent Quanta (GNEQ)

),,,(

),,(),,,(

2

mXfGNNPS

mfGMTFmXfGNEQ

ρρρ =

� Generalized Detective Quantum Efficiency (GDQE)

),(

),,,(),,,(

2 mXm

mXfGNEQmXfGDQE

inΦ= ρρ

� The generalized parameters are defined with reference to the object plane

Generalized System Evaluation Metrics

Kyprianou I, Rudin S, Bednarek DR, Hoffmann KR: Generalizing the MTF and DQE to include x-ray scatter and focalspot unsharpness: Application to a new micro-angiographic system for clinical use. Medical Physics, 32(2): 613-626, 2005.

Impact of varying the x-ray tube focal-spot size and air gaps

GMTFs

� Yadava et al., AAPM 2005, Medical Physics 32 (6), 2080 (2005)

0.3 mm focal-spot 0.6 mm focal-spot

DQE/GDQE

Summary (Educational Objectives):

1. Appreciate the progress being made in improved EIGI devices and in particular flow modifiers such as the asymmetric vascular stent (AVS) for aneurysm treatment.

2. Understand the operation of new high-resolution micro-angiographic systems including the MAF and SSXII.

3. Understand new objective image detector evaluations including INEE, GMTF, GDQE, and determination of MTF from noise response measurements alone.

Separate Structure, Quantum, Electronic Noise

INEE – Effect on DQE

Always Instrumentation Noise Limited

Instrumentation Noise Limited @ 2 µR

(((( )))) (((( ))))EvuTKgaEvu CCDADCpixel ,~ˆ,,NPS 22Secondary ηΦ====

(((( )))) (((( ))))EvuTgaEvu SYSpixel ,~ˆ,,NPS 222Primary ηΦ====

(((( )))) (((( )))) Eg

vuTgaEvuCsI

gSYSpixel

CsIε

η ,~ˆ,,NPS 222Excess Φ====

(((( )))) (((( ))))vuSEvu ADD ,,,NPSElectronic ====

(((( )))) (((( )))) 2Structure ,,,NPS EvuSEvu Structure====

Theoretical NPS(((( )))) (((( )))) (((( )))) (((( )))) (((( ))))vuSEvuTK

ggvuTgaEvuSEvu ADDPixelADC

CsI

gSYSpixelStructure

CsI ,,1~,~ˆ,,,NPS 2222Measured ++++

++++

++++++++====

εηΦ

(((( )))) (((( )))) (((( )))) (((( ))))vuCEvuBEvuAEvu ,,,,,NPS 2Measured ++++++++====

ElectronicSecondaryExcessPrimaryStrctureMeasured NPSNPSNPSNPSNPSNPS ++++++++++++++++====

Detector Comparison*

Detector System INEE Pixel (µm) Lag (frames) Frame Rate (fps)

MA 20.4 µR 43 None 4

MAF, SSXII <0.1 µR 35-48 None 30

XII <0.2 µR 120-300+ None 30

FPD** 2.75 µR ~300 5+ 30

*Kuhls-Gilcrist A, Jain A, Bednarek DR, Rudin S: Instrumentation Noise Equivalent Exposure (INEE):an investigation of spatial frequency effects (abstract). Medical Physics 2008, SU-DD-A4-6.

*Szczykutowicz, T, Kuhls-Gilcrist A, Bednarek DR, Rudin S: Instrumentation noise equivalent exposure(INEE) for routine quality assurance: INEE measurements on a clinical flat panel detector (abstract). Medical Physics 2008, MO-E-332-7.

**Roos et al., “Multiple gain ranging readout method to extend the dynamic range of amorphous silicon flat panel imagers”, Physics of Medical Imaging, Proc SPIE 5368, 139-149 (2004).

Dual Detector ROI Cone Beam CT

1. Chityala R, Hoffmann KR, Rudin S, Bednarek DR: Region-of-interest (ROI) Computed Tomography: Combining dual resolution XRII images (abstract). Medical Physics, 32(6): 2056, June 2005, MO-D-I-611-4. (AAPM05)2. Patel V, Ionita CN, Keleshis C, Sherman J, Hoffmann KR, Bednarek DR, Rudin S: First implementation of high-resolution dual-detector Region-of-Interest Cone-Beam Computed Tomography (ROI-CBCT) for a rotating C-arm gantry system (abstract). Medical Physics, TH-C-332-2. (AAPM08)3. Patel V, Hoffmann KR, Bednarek DR, Rudin S: Automatic registration technique for rotating-gantry dual-detector Region-of-Interest Cone-Beam Computed Tomography (ROI-CBCT) (abstract). Medical Physics, TH-D-332-4 (AAPM08)

Dual Detector ROI CBCT

Ionita CN, Patel V, Keleshis C,Hoffmann KR, Bednarek DR, Rudin S: Update on the development of a new dual detector (Micro-Angiographic Fluoroscope/Flat Panel) C-arm mounted system for endovascular image guided interventions (EIGI) (abstract). Medical Physics 2008, MO-D-332-7.

High Resolution ROI Detector Implementation

DeployedRetracted

MAF projection of stent deployed in rabbit carotid artery near constriction.

Dual Detector ROI-CBCTFPD-CBCT

First in –vivo3D ROI-CBCT

of a Stent

DQE of MAF

Asymmetric Vascular Stent(AVS)

Aneurysm treated with AVS

Side View Transverse View

Schematics of the AVS-treated aneurysms

Documents

Endovascular vs. Invasive Neuro -vascular Interventions · 3. X-ray image guidance vs. visual ... Ionita CN, Chang C, Sinelnikov A, Bednarek DR, ... SPIE vol. 6142 , pp. 6142R1 -11,