how i do cmr myocardial perfusion imaging scmr website 2006 christopher klassen md, phd university...
Post on 12-Jan-2016
213 Views
Preview:
TRANSCRIPT
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.
top related