Abstract 9203: Detecting Myocardial Ischemic Territories in the Setting of Acute Coronary Obstructions at Rest with Cardiac Phase-Resolved Blood Oxygen Level Dependent (CP-BOLD) MRI
Introduction: In the setting of ACS, particularly in non ST elevation myocardial infarction (NSTEMI), triaging patients for coronary catheterization from the emergency department can benefit from an imaging approach that does not resort to provocative stress or exogenous contrast media. We propose a MRI method that has the capacity to non-invasively and rapidly identify ischemic territories and assess functional status under resting conditions.
Hypothesis: Tested in a canine model, we hypothesize that on the basis of phasic changes in blood volume and oxygenation it is possible to arrive at an imaging metric that can identify myocardial territories affected by acute coronary obstruction without exogenous contrast media at rest.
Methods: Flow and motion compensated CP-BOLD and standard cine (cine) images were acquired at 1.5T in 11 canines at baseline and under severe LAD stenosis at rest. First-pass perfusion was performed in order to identify the affected and remote (healthy) territories in end-systolic (ES) and end-diastolic (ED) images. S/D, defined as a ratio of the mean intensity between ES and ED were computed from CP-BOLD and cine images. Two-way repeated measurement ANOVAs were used to test the effects of region (remote, affected) and condition (baseline, stenosis) and their interaction on S/Ds.
Results: On CP-BOLD, affected regions had S/D<1 consistent with the expectations of physiologic changes in blood volume and oxygenation. No effects were found on S/D computed from cine, indicating that the BOLD sensitivity from CP-BOLD MRI is the principal mechanism enabling the detection of myocardial ischemic territories at rest.
Conclusions: S/D < 1 (from CP-BOLD MRI) can serve as a potential biomarker for identifying ischemic territories under rest. Since cardiac-phased resolved images are acquired with CP-BOLD, functional changes can also be determined without additional scans, permitting rapid assessment of ACS. The method remains to be tested in patients.
- © 2011 by American Heart Association, Inc.