Renal blood flow measurement by positron emission tomography using O-15-labeled water

Background. Only few noninvasive methods have the potential to quantitate r enal blood flow (RBF) in humans. Positron emission tomography (PET) is a cl inical imaging method that can be used to measure the tissue blood flow non invasively. The purpose of this study was to validate PET measurement of RB F using O-15-labeled water ((H2O)-O-15), a tracer that allows repeated meas urements at short time intervals. Methods. RBF was measured in six pigs by PET and by radioactive microsphere s (MS). Three measurements were performed in each pig at baseline (BL), dur ing vascular expansion and dopamine infusion (DA; 20 mu g.kg(-1).min(-1) in travenously), and during angiotensin II (Ang II) infusion (50 ng kg(-1).min (-1) intravenously). RBF was estimated from aortic and renal tracer kinetic s using a model adapted from the blood flow model described by Kety and Smi th. Results. PET and MS values correlated strongly (gamma = 0.79x + 42, r = 0.9 3, P < 0.0001) over the RBF range from 100 to 500 mL.min(-1).100 g(-1). Pha rmacologically induced changes were significant and were measured equally w ell by PET and MS: 38 and 39%, respectively, below BL (P < 0.005 and P < 0. 05) under Ang II, and 47 and 48%, respectively, above BL (P < 0.005 and P < 0.01) under DA. A Bland and Altman representation showed a low average dif ference of -17 +/- 45 mL.min(-1). 100 g(-1) (mean +/- SD). Conclusion. To our knowledge, this study provides the first validation of R BF measurement by PET using (H2O)-O-15 over a large range of RBF values (10 0 to 500 mL.min(-1).100 g(-1)), which correspond to RBF values in both heal thy subjects and in patients suffering from chronic renal failure.