Brain perfusion CT compared with(15)O-H(2)O-PET in healthy subjects

BACKGROUND: Regional cerebral blood flow [rCBF] measurements are valuable for identifying angiogenically active tumours, and perfusion computed tomography [CT] has been suggested for that purpose. This study aimed to validate rCBF measurements by perfusion CT with positron-emission tomography [PET] and(15)O-labelled water [(15)O-H(2)O] in healthy subjects. METHODS: RCBF was measured twice in 12 healthy subjects with(15)O-H(2)O PET and once with perfusion CT performed over the basal ganglia. Matching rCBF values in regions of interest were compared. RESULTS: Measured with perfusion CT, rCBF was significantly and systematically overestimated. White matter rCBF values were 17.4 ± 2.0 (mean ± SD) mL min(-1 )100 g(-1 )for PET and 21.8 ± 3.4 mL min(-1 )100 g(-1 )for perfusion CT. Grey matter rCBF values were 48.7 ± 5.0 mL min(-1 )100 g(-1 )for PET and 71.8 ± 8.0 mL min(-1 )100 g(-1 )for perfusion CT. The overestimation of grey matter rCBF could be reduced from 47% to 20% after normalization to white matter rCBF, but the difference was still significant. CONCLUSION: RCBF measured with perfusion CT does contain perfusion information, but neither quantitative nor relative values can substitute rCBF measured by(15)O-H(2)O PET yet. This, however, does not necessarily preclude a useful role in patient management.