PT - JOURNAL ARTICLE AU - Hidehiko Okazawa AU - Manouchehr Vafaee TI - Effect of Vascular Radioactivity on Regional Values of Cerebral Blood Flow: Evaluation of Methods for H<sub>2</sub><sup>15</sup>O PET to Distinguish Cerebral Perfusion from Blood Volume DP - 2001 Jul 01 TA - Journal of Nuclear Medicine PG - 1032--1039 VI - 42 IP - 7 4099 - http://jnm.snmjournals.org/content/42/7/1032.short 4100 - http://jnm.snmjournals.org/content/42/7/1032.full SO - J Nucl Med2001 Jul 01; 42 AB - To evaluate the appropriate model for calculating regional cerebral blood flow (rCBF) with PET and H215O, the values obtained from 1- and 2-compartment analyses were compared. Methods: Dynamic PET scans were performed on 12 healthy volunteers after injection of H215O in 2 conditions of baseline and visual stimulation. Calculation of rCBF was performed using the 2-weighted integral (WI) and autoradiographic methods for the 1-compartment analysis, and the 3-WI method was followed for the 2-compartment analysis. Arterial blood radioactivity was counted continuously and corrected for delay and dispersion. The rCBF images were transformed into the Talairach space and analyzed by statistical parametric mapping to identify regional differences in the 2 methods. The values obtained from regions of interest also were compared. Results: Although the difference in global CBF between the 2 models was not significant, rCBF values in the large arteries and neighbor areas were significantly greater in the 2-WI method than in the 3-WI method. However, regional differences in the activation studies were not affected when the 2 methods were compared. The images of cerebral arterial blood volume (V0) obtained by the 3-WI method showed a significant increase in V0 in the visual cortex during visual stimulation. Conclusion: These results suggest that the rCBF values in the 1-compartment analysis were affected by radioactivity in the vessels. The 3-WI method could provide rCBF values that are less influenced by vascular radioactivity and also show differences in V0 in PET activation studies.