VIBOT 4

2011

Literature Review of Image Processing Methods for Myocardial Infarction Studies in MRI and CT-Scan

By:Vanya Vabrina V

Rui Hua

What is Myocardial Infarction (MI)?

Heart attack

Need immediate

treatment

Type of Diagnosis

SPECT limitation:ExpensiveDose heavy + ionizing radiationArtifact pronePoor spatial resolution

Coronary Angiography limitation:Invasive method!

Non-Invasive Solutions:

CT-Scan and MRIPerfusion Imaging

MI limited flow

Cardiac CTMulti-Detector Computed Tomography

(MDCT)

o High-resolution 3D of the moving heart and study the coronary vesselso Cover volumes of anatomy within a single breath-holdo Improved spatial resolutiono Improved temporal resolution

Cardiac MRI

Fast MRI Sequence Gradient EchoMany application in clinical Cardiac MRI:Cardiac function: Cine – MRIPerfusion SSFP Bright blood Breath-hold Inversion recovery pre-pulse

CT – Perfusion Imaging

Pharmacologic Stress agent : Adenosine Contrast agent : Iodine based (e.g, Visipaque) [concentration ~ x-ray absorbtion] Signal-density-time curve ~ CT attenuation over time

MR-Perfusion Imaging

PharmacologicStress agent : AdenosineContrast agent: Gadolinium

(Gd) Signal intensity-time curve ~

contrast agent

Criteria of MI – CT

First-Pass Hypo enhancement

Criteria of MI – MRI

First Pass Imaging (FP)

Examines myocardial tissue perfusion (wash in)

MI criteria: slow wash inHypo-enhancement

Criteria of MI – MRI

Delay enhancement Imaging (DE)

Examine the kinetics of contrast agent elimination (wash out)

MI criteria: slow wash out

Hyper-enhancement

Transmural MI

Sub-endocardial MI

Criteria of MI : DE-MRI

Image Post-Processing

…of MI Diagnosis in CT Scan and MRI Perfusion

Imaging

CT MYOCARDIAL PERFUSION ANALYSIS

CT – Semi Quantitative

First pass imaging upslope analysis can provide semi quantitative measure for myocardial perfusion

Up slope analysisTAC (Time Attenuation Curve)

CT – Semi Quantitative

MI region myocardium with 1 SD below the mean of the remote regionClustering algorithmResult – MI : hypo-perfused blue area

17-segment polar plot of MDCT-derived myocardial signal densities

CT –Visual Analysis

17 segment model

Scored - the absence/presence of a perfusion defect

Graded - reversibility

MRI MYOCARDIAL PERFUSION ANALYSIS

MRI MYOCARDIAL PERFUSION ANALYSIS

Qualitative

Visual assessment

MRI MYOCARDIAL PERFUSION ANALYSIS

Automatic endocardial and epicardial borders detection

Snake Contour

Endocardial delineation: Gradient Vector Flow (GVF) snake algorithm on an edge map

Epicardial delineation:

Thickness

Endocardial contour

Epicardial contour

MRI MYOCARDIAL PERFUSION ANALYSIS

Automatic endocardial and epicardial borders detectionCenterline Method

Geometrical Template dark circular kernel template

Modeled as: Centerline and width

Template deformation to find parameters minimizing a criterion

MRI – FIRST PASS IMAGING

Wash-in within the different regions were assessed by signal-intensity (SI) time curve analysis

MRI – DELAY ENHANCED IMAGING

Quantitative FACT (Feature Analysis and Combined

Threshold )method

MR Image Contoured Image

Histogram Image Pre-Processing

2SD Thresho

ld

Feature analysis FWHM

Region contouring

Feature analysis

Output

MRI – DELAY ENHANCED IMAGING

FACT Result – Contoured MI

MRI – DELAY ENHANCED IMAGING

Quantification MI Volume combine all MI area in contiguous

slicesMeasurement of MI size from the result of FACT

algorithm. Sector based viability measurement

MRI – DELAY ENHANCED IMAGING

Peri-infarct

Core-infarct

Comparison

Object CT Scan MRIContrast

assesmentAttenuation Signal intensity

Criteria in FP Hypo-enhancement

Hypo-enhancement

Criteria in DE Hyper-enhancement

Hyper-enhancement

Functional recovery

Early hypoenhanced

Prediction in DE

Infarct size Over-estimation Good prediction

Late hypoenhancment

Well correlated Well correlated

Comparison Modalities Advantages Limitations

MRI

High CNRHigh accuracy

Limited spatial resolution of MRI in axial direction (slice thickness)

Low ionizing radiation and less toxic contrast agent

Higher cost. Longer scanning time

Highly attractive for viability imaging

Restriction to patients with implanted electronic devices

CT SCAN

Improved spatial resolution

High radiation and contrast dose

Faster/high temporal resolution

Lower CNR

Greatly reduced slice width

Require hardware development to reduce motion artifact

ConclusionMyocardial infarction can be studied non-invasively

using CT and MRI Perfusion imaging.

MRI has low radiation and higher CNR, compared to CT

Image post-processing and criteria (hypo-enhancement in first-pass and hyper-enhancement in delay-enhanced imaging) of MI in CT and MRI are almost similar

Quantification of MI is more accurately evaluated with MRI.

THANK YOU…

References

http://www.medicinenet.com/heart_attack http://www.nhlbi.nih.gov/health/dci/Diseases/HeartAttack /HeartAttack_WhatIs.html

A.C. Lardo, A.S. Cordeiro, et.al. Contrast-Enhanced Multidetector Computed Tomography Viability Imaging After Myocardial Infarction Characterization of Myocyte Death, Microvascular Obstruction, and Chronic Scar. 2006. AHA Journal Circulation, Dallas.113:394-404

Richard T. George, et.al. Multidetector Computed Tomography Myocardial Perfusion Imaging During Adenosine Stress. 2006. Journal of the American College of Cardiology. Vol. 48, No. 1.

C.Valdiviezo, M.Ambrose, et al. Review: Quantitative and qualitative analysis and interpretation of CT perfusion imaging. 2007. Journal of Nuclear Cardiology. Volume 17, Number 6;1091–100.

K. Nieman, M.D. Shapiro, et al. Reperfused Myocardial Infarction: Contrast-enhanced 64-Section CT in Comparison to MR Imaging.2008. Radiology: Volume 247: Number 1—April.

P.Hunold, T.Schlosser. Myocardial Late Enhancement in Contrast-Enhanced Cardiac MRI: Distinction Between Infarction Scar and Non–Infarction-Related Disease. AJR 2005;184:1420–1426

B. L. Gerber, B.Belge, et al. Characterization of Acute and Chronic Myocardial Infarcts by Multidetector Computed Tomography Comparison With Contrast-Enhanced Magnetic Resonance. 2006. AHA Circulation 113;823-833

References

• W.Ksai, K.M. Holohan. Myocardial Perfusion Imaging from Echocardiography to SPECT, PET, CT, and MRI—Recent Advances and Applications. US Cardiology. Touch Briefings, 2010.

A.T. Yan, A. J. Shayne, Characterization of the Peri-Infarct Zone by Contrast-Enhanced Cardiac Magnetic Resonance Imaging Is a Powerful Predictor of Post–Myocardial Infarction Mortality. 2006. AHA Circulation 114;32-39.

A.Schmidt, M.F Azevedo, et al. Infarct Tissue Heterogeneity by Magnetic Resonance Imaging Identifies Enhanced Cardiac Arrhythmia Susceptibility in Patients With Left Ventricular Dysfunction. 2007. AHA Circulation.115;2006-2014.

Glenn S. Slavin, et al. First-Pass Myocardial Perfusion MR Imagingwith Interleaved Notched Saturation: Feasibility Study. Radiology, April 2001. Vol.219: pp.259 – 263.

Li-Yueh Hsu, et al. Quantitative Myocardial Infarction on Delayed Enhancement MRI. Part I: Animal Validation of an Automated Feature Analysis and Combined Thresholding Infarct Sizing Algorithm. 2006. JOURNAL OF MAGNETIC RESONANCE IMAGING 23:298–308.

Li-Yueh Hsu, et al. Quantitative Myocardial Infarction on Delayed Enhancement MRI. Part II: Clinical Application of an Automated Feature Analysis and Combined Thresholding Infarct Sizing Algorithm. 2006. JOURNAL OF MAGNETIC RESONANCE IMAGING 23:309–314.