Cardiac phase-resolved blood oxygen-sensitive steady-state free precession MRI for evaluating the functional significance of coronary artery stenosis.

Objective: This study investigates whether cardiac phase-resolved steady-state free precession (SSFP) magnetic resonance imaging can be used to detect regional myocardial oxygen deficits (MODs) and other functional changes (wall motion and ejection fraction) caused by coronary artery stenosis in a canine model.

Materials And Methods: Subsequent to changing the degree of stenosis of the left circumflex arteries of 8 dogs, cardiac phase-resolved SSFP images were acquired at baseline, prestensois (with adenosine), and at different stenosis levels and were correlated against true flow changes. Wall motion and ejection fraction changes also were assessed under the different stenosis levels.

Results: MODs caused by coronary stenosis were observed with the SSFP-based technique and were strongly correlated with microsphere-based regional flow measurements (r=0.80, P<0.01). From the phase-resolved SSFP images, statistically significant (P < 0.01) changes in wall motion and ejection fraction were also observed at severe stenosis.

Conclusion: The SSFP method can simultaneously detect MODs, wall motion changes, and left ventricular dysfunction caused by coronary artery stenosis within a single scan in a controlled canine model.