Purpose: To determine the feasibility of T2-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 OEFhyperemia was calculated with the corresponding T2. 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 T2 increase (3.06% ± 2.74%, in contrast to 10.19% ± .12% in the normal region). The average OEFs in the normally and abnormally perfused myocardial territories were 0.21 ± .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 OEFhyperemia and approximate the MPR, and can distinguish segments perfused by defected coronary artery.
- BOLD imaging
- Myocardial oxygen extraction fraction
- Myocardial perfusion reserve