Abstract
Purpose
To determine the feasibility of T~2~‐weighted BOLD imaging for estimating regional myocardial oxygen extraction fraction (OEF) and approximating perfusion reserve (MPR) simultaneously in a canine model with moderate coronary artery stenosis.
Materials and Methods
Eight mongrel dogs with moderate coronary artery stenosis underwent BOLD imaging at rest and during dipyridamole‐induced hyperemia, using a turbo spin echo (TSE) sequence. Based on a two‐compartment model, myocardial OEF~hyperemia~ was calculated with the corresponding T~2~. MPR could be approximated based on Fick's law.
Results
During responsive hyperemia, a regional hypointensity was observed in the abnormally perfused myocardium, reflecting a relatively smaller myocardial T~2~ increase (3.06% ± 2.74%, in contrast to 10.19% ± 4.12% in the normal region). The average OEFs in the normally and abnormally perfused myocardial territories were 0.21 ± 0.11 and 0.43 ± 0.12, respectively. For the MPR approximated from the BOLD imaging, a strong correlation (R = 0.9) in the normal myocardium and a good correlation (R = 0.6) distal to the stenosis were obtained compared to microsphere results.
Conclusion
In a canine model with moderate coronary artery stenosis, TSE‐based BOLD imaging can quantitatively estimate the regional OEF~hyperemia~ and approximate the MPR, and can distinguish segments perfused by defected coronary artery. J. Magn. Reson. Imaging 2007;26:72–79. © 2007 Wiley‐Liss, Inc.