Omission of [(15)O]CO scan for PET CMRO(2) examination using (15)O-labelled compounds

CBF, OEF and CMRO(2) provide us important clinical indices and are used for assessing ischemic degree in cerebrovascular disorders. These quantitative images can be measured by PET using (15)O-labelled tracers such as C(15)O, C(15)O(2) and (15)O(2). To reduce the time of scan, one possibility is to omit the use of CBV data. The present study investigated the influence of fixing the CBV to OEF and CMRO(2) values on subjects with and without cerebrovascular disorders.

The study consisted of three groups, namely, GROUP-0 (n = 10), GROUP-1 (n = 9), and GROUP-2 (n = 10), corresponding to--without significant disorder, with elevated CBV, and with reduced CBF and elevated OEF, respectively. All subjects received PET examination and using the PET data OEF and CMRO(2) images were computed by fixing CBV and with CBV data. The computed OEF and CMRO(2) values were compared between the methods.

The OEF and CMRO(2) values obtained by fixing the CBV were around 10% underestimation against that with CBV data. The regression analysis showed that these values were comparable (r = 0.93-0.98, P < 0.001). The simulation showed that fixing of the CBV would not derive significant error in either OEF or CMRO(2) values, when changed from 0 to 0.08 ml/g.

This study shows the feasibility of fixing the CBV value for computing OEF and CMRO(2) values in the PET examination, suggesting the CO scan could be eliminated.