Reproducibility of measurements of regional myocardial blood flow in a model of coronary artery disease: Comparison of H215O and 13NH3 PET techniques.

UNLABELLED PET absolute myocardial blood flow (MBF) with H(2)15O and 13NH3 are widely used in clinical and research settings. However, their reproducibility with a 16-myocardial segment model has not been examined in chronic coronary artery disease (CAD). We examined the short-term reproducibility of PET H(2)15O MBF and PET 13NH3 MBF in an animal model of chronic CAD. METHODS Twelve swine (mean weight +/- SD, 38 +/- 5 kg) underwent percutaneous placement of a copper stent in the mid circumflex coronary artery, resulting in an intense inflammatory fibrotic reaction with luminal stenosis at 4 wk. Each animal underwent repeated resting MBF measurements by PET H(2)15O and PET 13NH3. Attenuation-corrected images were analyzed using commercial software to yield absolute MBF (mL/min/g) in 16 myocardial segments. MBF was also normalized to the rate.pressure product (RPP). RESULTS By Bland-Altman reproducibility plots, the mean difference was 0.01 +/- 0.18 mL/min/g and 0.01 +/- 0.11 mL/min/g, with confidence limits of +/-0.36 and +/-0.22 mL/min/g for uncorrected regional PET H(2)15O MBF and for uncorrected regional PET 13NH3 MBF, respectively. The repeatability coefficient ranged from 0.09 to 0.43 mL/min/g for H(2)15O and from 0.09 to 0.18 mL/min/g for 13NH3 regional MBF. RPP correction did not improve reproducibility for either PET H(2)15O or PET 13NH3 MBF. The mean difference in PET H(2)15O MBF was 0.03 +/- 0.14 mL/min/g and 0.02 +/- 0.19 mL/min/g for infarcted and remote regions, respectively, and in PET 13NH3 MBF was 0.03 +/- 0.11 mL/min/g and 0.00 +/- 0.09 mL/min/g for infarcted and remote regions, respectively. CONCLUSION PET H(2)15O and PET 13NH3 resting MBF showed excellent reproducibility in a closed-chest animal model of chronic CAD. Resting PET 13NH3 MBF was more reproducible than resting PET H(2)15O MBF. A high level of reproducibility was maintained in areas of lower flow with infarction for both isotopes.