How I do CMR Myocardial Perfusion imaging

SCMR Website 2006

Christopher Klassen MD, PHDUniversity of Florida Health Science CenterDr. Norbert Wilke

This presentation is posted for members of scmr as an educational guide – it represents the views and practices of

the author, and not necessarily those of SCMR.

Two phases of myocardial enhancement after contrast injection

1st Dynamic First Pass Perfusion Imaging Occurs within the first minute following injectionWash in and Wash out of contrast agent Transient differences in signal intensity indicate potential ischemia

2nd Delayed Enhancement Imaging 5-30 minutes after injection Hyperenhancement indicates potential infarction

Sequences

There are a number of different sequences that can be applied to myocardial perfusion imaging

TurboFLASHEPIFISP, BFFE

Acquisition Protocol

1. Localizer views of 2chamber, 3ch, 4ch Long Axis2. Short Axis stack of localizer views3. Cine of 4ch Long Axis to examine base motion 4. Infuse stress agent (Adenosine 140 mcg/kg/min, peripheral IV)

Gadolinium Contrast + Dynamic Perfusion imaging (hyperemia)

5. Acquire complete cine exam (short axis + long axis views) 6. Gadolinium Contrast + Dynamic Perfusion imaging (rest)

7. Perform Delayed Enhancement Myocardial Viability imaging

Image Interpretation

Perfusion Defects Criteria Defect is present in at least 3-4 frames during peak signal intensity Defect size is constant from frame to frame Defect localizes to a physiologic consistent distribution according to

coronary artery territories Scenario 1: Defect is present at stress and rest and on delayed

enhancement (DCE) Scenario 2: Defect is present during pharmacologic stress but not DCE Signal intensity of the defect doesn’t fluctuate from frame to frame Quantitative parameters are reduced as derived from the myocardial

signal intensity curves.

Perfusion Artifacts

Relative Converse of Previous slide Defect fluctuates in signal intensity and or size Defect is only present transiently in only 1-2 frames Defect is not consistent with physiology of coronary territories defect is present only at rest and not stress Quantitative parameters demonstrate noisy signal curves

Differential Diagnosis 1. Subendocardial Area of reduced signal intensity on

stress perfusion imaging Ischemia with significant or intermediate signal intensity Advanced microvascular disease

2. Circumferential subendocardial defect3 vessel disease Microvascular disease

3. Defect at rest and stressMyocardial infarction

ReportingRecommend AHA 17 segment model of

myocardium 3 slices (base, mid, apex) Base and mid slice divided into 6 radial sectors

(anterior septal, anterior, anteriolateral, inferolateral, inferior, inferiorseptal)

Apex divided into 4 radial sectors (septal, anterior, inferior, lateral)

One segment at tip of apex seen only on long axis, if available

Myocardial Perfusion (Various Clinical Scenarios)

Cine Function Rest Perfusion Stress Perfusion

Delayed Enhancement

Imaging

Normal normal no defects no defects normal

Infarctionscar with wall

thinning Severe defect Severe defect hyper enhancement

Hibernating mild hypokinesia mild defectmild perfusion

defect normal

Stunning mild hypokinesia normal mild perfusion

defect normal

Ischemia normalnormal or mildly

reduced perfusion defect normal

Myocardial Perfusion Case 1

Three short axis and one 2 chamber LA using Turboflash sequence. Adenosine images top row, and resting bottom row. Arrow points to SubendocardialDefect at the septal wall.

Delayed Enhancement Case 1

Arrow points to hyperenhancement in the septal wall.

Myocardial Perfusion Case 2

Adenosine images top row, and resting bottom row. Arrow points to Defect at the posterior wall.

Delayed Enhancement Case 2

Negative delayed enhancement scan

Qualitative interpretation as above For quantitative and semi-quantitative interpretation

Contour endocardial and epicardial borders to measure the myocardial signal intensity curve

Generate myocardial and LV blood signal intensity time curves Derive semi-quantitative measures such as

Slope, Time to Peak, Max upslope, Peak from the signal intensity curves

Calculate absolute myocardial blood flow (ml/min/g) with further fitting of the signal intensity time curve.

Myocardial perfusion reserve is defined as the ratio of hyperemic flow to resting flow and also can be used clinically.

MR quantification of the myocardial perfusion reserve with aFermi function model for constrained deconvolutionM. Jerosch-Herold, N. Wilke, A. Stillman, R. WilsonMed. Phys. 25 (1), 73-84, Jan 1998

Perfusion Analysis

Quantitative Perfusion Analysis

Clinically this has been useful in extending qualitative perfusion analysis in the following ways1. differentiating artifact from actual defects 2. differentiating microvascular disease from ischemia3. Determining the potential degree of coronary stenosis

based on perfusion reserve4. assist in determining which coronary arteries are affected5. more accurate comparison with follow up scans6. eventually to determine prognostic risk as based on the

MESA trial.