Transcript How to perform Perfusion imaging

How I do CMR Myocardial
Perfusion imaging
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.
SCMR Website 2006
Christopher Klassen MD, PHD
University of Florida Health Science Center
Dr. Norbert Wilke
 Two phases of myocardial enhancement after contrast
injection
 1st Dynamic First Pass Perfusion Imaging
 Occurs within the first minute following injection
 Wash 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
TurboFLASH
EPI
FISP, BFFE
Acquisition Protocol
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Localizer views of 2chamber, 3ch, 4ch Long Axis
Short Axis stack of localizer views
Cine of 4ch Long Axis to examine base motion
Infuse stress agent (Adenosine 140 mcg/kg/min, peripheral IV)
Gadolinium Contrast + Dynamic Perfusion imaging
(hyperemia)
Acquire complete cine exam (short axis + long axis views)
Gadolinium Contrast + Dynamic Perfusion imaging (rest)
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
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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 defect
 3 vessel disease
 Microvascular disease
 3. Defect at rest and stress
 Myocardial infarction
Reporting
Recommend 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)
Delayed
Enhancement
Imaging
Cine Function
Rest Perfusion
Stress Perfusion
Normal
normal
no defects
no defects
normal
Infarction
scar with wall
thinning
Severe defect
Severe defect
hyper enhancement
mild defect
mild perfusion
defect
normal
mild hypokinesia
normal
mild perfusion
defect
normal
normal
normal or mildly
reduced
perfusion defect
normal
Hibernating
Stunning
Ischemia
mild hypokinesia
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 Subendocardial
Defect 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
Perfusion Analysis
 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 a
Fermi function model for constrained deconvolution
M. Jerosch-Herold, N. Wilke, A. Stillman, R. Wilson
Med. Phys. 25 (1), 73-84, Jan 1998
Quantitative Perfusion Analysis
 Clinically this has been useful in extending
qualitative perfusion analysis in the following ways
 1. differentiating artifact from actual defects
 2. differentiating microvascular disease from ischemia
 3. Determining the potential degree of coronary stenosis
based on perfusion reserve
 4. assist in determining which coronary arteries are affected
 5. more accurate comparison with follow up scans
 6. eventually to determine prognostic risk as based on the
MESA trial.