Effects of scatter and attenuation correction on quantitative analysis of β-CIT brain SPET

The aim of this study was to evaluate the effects of scatter correction (SC) and attenuation correction (AC) on the quantification of dopamine transporters using I-123-beta-CIT brain SPET images. Quantitative analysis was carried out using static SPET images obtained 23 h after injection. We calculated V-3" [(striatal-occipital)/occipital ratio] values from images without correction, with AC, and with SC and AC. Two types of regions of interest (ROI) were plated on the striatum: a small square ROI and a larger ROI containing most of the striatum. After validating the correction method in a phantom experiment, a human study was carried out involving eight normal volunteers and 15 patients. The larger ROI yielded smaller V-3" values. The effect of attenuation correction was modest, whereas that of scatter correction was marked. It was shown that beta-CIT SPET quantification was affected by the size of the ROI, photon scattering and attenuation, and that scatter and attenuation correction improved the accuracy of the quantification. Methodological standardization in image processing and the type of ROI should be considered when a multi-centre trial is planned. ((C) 1999 Lippincott Williams & Wilkins).