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Renal blood flow measurement by positron emission tomography using 15O-labeled water
L Juillard1, M F Janier, D Fouque
1Département de Néphrologie, Hôpital Edouard Herriot, Lyon, France. laurent.juillard@chu-lyon.fr
Background:
Only few noninvasive methods have the potential to quantitate renal blood flow (RBF) in humans. Positron emission tomography (PET) is a clinical imaging method that can be used to measure the tissue blood flow noninvasively. The purpose of this study was to validate PET measurement of RBF using 15O-labeled water (H215O), a tracer that allows repeated measurements at short time intervals.
Methods:
RBF was measured in six pigs by PET and by radioactive microspheres (MS). Three measurements were performed in each pig at baseline (BL), during vascular expansion and dopamine infusion (DA; 20 microg. kg-1. min-1 intravenously), and during angiotensin II (Ang II) infusion (50 ng. kg-1. min-1 intravenously). RBF was estimated from aortic and renal tracer kinetics using a model adapted from the blood flow model described by Kety and Smith.
Results:
PET and MS values correlated strongly (y = 0.79x + 42, r = 0.93, P < 0.0001) over the RBF range from 100 to 500 mL. min-1. 100 g-1. Pharmacologically induced changes were significant and were measured equally well 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 difference of -17 +/- 45 mL. min-1. 100 g-1 (mean +/- SD).
Conclusion:
To our knowledge, this study provides the first validation of RBF measurement by PET using H215O over a large range of RBF values (100 to 500 mL. min-1. 100 g-1), which correspond to RBF values in both healthy subjects and in patients suffering from chronic renal failure.