Noninvasive rCBF determination by 133XE-inhalation with the gamma camera and functional imaging of wash-in and wash-out

In 47 patients with cerebrovascular disease (CVD) a noninvasive determination of global and regional cerebral blood flow (CBF) was performed with the gamma camera. A new approach was developed for region definition and for evaluation of the 'start-fit-time' as the point of minimal contamination of the recorded data by extracerebral scatter and recirculation using the region of interest (ROI)-technique in the camera field of view. In comparison with the results of probe measurement of end-tidal exhalation air no significant differences were seen and values obtained were well in the range reported by other authors. Initial slope (IS), gray matter flow (Fl) and CBF-15 were used as quantitative parameters and were able to distinguish significantly (P < 0.001) between normals, patients with mild CVD, and severe CVD. Intraexamination variation coefficient (VC) was 5%, interexamination VC was 8%. Functional, parametric images of wash-in for easier ROI-definition and judgement of isotope supply and of wash-out were generated by a computer analysis and were found to be sensitive indicators for arterial blood supply and wash-out velocity. Thus it was possible to recalculate regional flow values in focal areas exactly corresponding to abnormalities seen on the functional images. So the full regional information of functional images can be combined with the quantitative data in selectable areas. By this noninvasive, easily performed method focal neurological deficits can be evaluated with high accuracy with conventional nuclear medicine equipment. (orig.)