Purpose To validate a new T2-prepared method for the quantification of regional myocardial O2 consumption during pharmacologic stress with positron emission tomography (PET). Materials and Methods A T2 prepared gradient-echo sequence was modified to measure myocardial T2 within a single breath-hold. Six beagle dogs were randomly selected for the induction of coronary artery stenosis. Magnetic resonance imaging (MRI) experiments were performed with the T2 imaging and first-pass perfusion imaging at rest and during either dobutamine- or dipyridamole-induced hyperemia. Myocardial blood flow (MBF) was quantified using a previously developed model-free algorithm. Hyperemic myocardial O 2 extraction fraction (OEF) and consumption (MVO2) were calculated using a two-compartment model developed previously. PET imaging using 11C-acetate and 15O-water was performed in the same day to validate OEF, MBF, and MVO2 measurements. Results The T 2-prepared mapping sequence measured regional myocardial T 2 with a repeatability of 2.3%. By myocardial segment-basis analysis, MBF measured by MRI is closely correlated with that measured by PET (R 2 = 0.85, n = 22). Similar correlation coefficients were observed for hyperemic OEF (R2 = 0.90, n = 9, mean difference of PET - MRI = -2.4%) and MVO2 (R2 = 0.83, n = 7, mean difference = 4.2%). Conclusion The T2-prepared imaging method may allow quantitative estimation of regional myocardial oxygenation with relatively good accuracy. The precision of the method remains to be improved.
- myocardial oxygen consumption
- myocardial perfusion reserve