Combined Long? and Short?Axis Myocardial Perfusion Cardiovascular Magnetic Resonance

Abstract

To date, myocardial perfusion cardiovascular magnetic resonance (CMR) has been reported in single and multiple short-axis slices. Three short-axis planes can assess 16 segments of the standard 17-segment myocardial model, but this approach fails to assess the ventricular apex that requires at least one long-axis plane. We therefore evaluated the feasibility and benefit of combined long- and short-axis perfusion CMR to enable complete 17 segments coverage for comprehensive myocardial perfusion assessment. Using a hybrid echo planar imaging (EPI) sequence, we performed rest and adenosine stress first-pass perfusion CMR studies with 3 short-axis (basal, mid, apical) planes, and additional long-axis planes in the same cardiac cycle in a broad range of cardiology patients. Perfusion CMR was performed in 53 consecutive patients using the combined short-long-axis imaging protocol. Twenty-nine of those studied had known or suspected coronary artery disease (CAD), 18 hypertrophic cardiomyopathy, and 6 suspected microvascular perfusion abnormalities. In 39 patients (70%), it was possible to acquire 5 slices at rest and stress including both the horizontal and vertical long axes. In 15 patients (27%), only one long-axis could be acquired, and in 2 patients (5%) only 3 slices (short axis) could be obtained. However, in none of the patients with known or suspected CAD was apical ischemia demonstrated by the long-axis views, despite apical ischemia having been demonstrated with recent SPECT studies in 8 of these patients. Rest-stress myocardial perfusion CMR is able to achieve complete segmental coverage of the myocardium using the combined short-long axis approach using an EPI sequence in 97% of a long series of consecutive cardiology patients, while maintaining excellent spatial resolution. However, the long-axis views were not found to be able to demonstrate inducible perfusion defects in the apex.