Brain perfusion CT compared with ¹⁵O-H₂O PET in patients with primary brain tumours

Perfusion CT (PCT) measurements of regional cerebral blood flow (rCBF) have been proposed as a fast and easy method for identifying angiogenically active tumours. In this study, quantitative PCT rCBF measurements in patients with brain tumours were compared to the gold standard PET rCBF with (15)O-labelled water ((15)O-H(2)O).

On the same day within a few hours, rCBF was measured in ten adult patients with treatment-naïve primary brain tumours, twice using (15)O-H(2)O PET and once with PCT performed over the central part of the tumour. Matching rCBF values in tumour and contralateral healthy regions of interest were compared.

PCT overestimated intratumoural blood flow in all patients with volume-weighted mean rCBF values of 28.2 ± 18.8 ml min(-1) 100 ml(-1) for PET and 78.9 ± 41.8 ml min(-1) 100 ml(-1) for PCT. There was a significant method by tumour grade interaction with a significant tumour grade rCBF difference for PCT of 32.9 ± 15.8 ml min(-1) 100 ml(-1) for low-grade (WHO I + II) and 81.5 ± 15.4 ml min(-1) 100 ml(-1) for high-grade (WHO III + IV) tumours, but not for PET. The rCBF PCT and PET correlation was only significant within tumours in two patients.

Although intratumoural blood flow measured by PCT may add valuable information on tumour grade, the method cannot substitute quantitative measurements of blood flow by PET and (15)O-H(2)O PET in brain tumours.