BRAIN SPECT WITH I-123 IODOBENZAMIDE (IBZ M) - ASPECTS OF SEMIQUANTITATIVE EVALUATION

The striatal dopamin-D2-receptor uptakte of I-123-IBZM in 32 patients (18 without and 14 under therapy with typical neuroleptics) was measur ed semiquantitatively using different ROI techniques. The aim of the s tudy was to evaluate the influence of these techniques on the differen t ratios (striatum/cortex) found by various examiners. Using the same SPECT system no major differences were found between rectangular and m anually drawn ROIs of the same size. All ROI techniques could differen tiate between patients with and without therapy on a highly significan t level. Therefore, the resulting ratio is mainly dependent on the spa tial resolution of the camera system and only to a relatively minor ex tent on the ROI technique. Ratios obtained by different observers are not comparable quantitatively.