108 Objectives To diagnose the dementia subtypes has significant information for determining the treatment strategies and predicting the clinical courses. Recently, many dementia patients undergo dopamine transporter (DAT) imaging, in addition to brain perfusion imaging to investigate the subtypes of dementia. However, patients must wait for tracer decay when using the conventional method, and this is burdensome for dementia patients and often delays the decision making for treatment. We developed a prototype CdTe SPECT system with 4-Pixel Matched Collimator for brain study. This system provides high energy resolution (6.6%), high sensitivity (220 cps/MBq/head) and provide high spatial resolution images of I-123 and Tc-99m simultaneously. The aim of this study was to evaluate findings and quantification on dual isotope study of cerebral blood flow (CBF) and Dopamine transporter (DAT) images with the new SPECT system. Methods We prospectively enrolled 21 patients with cognitive disorder. Every patient underwent imaging examinations on the same schedule. We used 3-head scanner (GCA-9300R, TOSHIBA) as a conventional scanner. Both 99mTc-ECD (CBF) and 123I-IFP (DAT) scans were independently performed with the conventional scanner on separate days, and simultaneously performed with the new system on another day. CBF and DAT images were both visually and quantitatively analyzed.For visual analyses, two nuclear medicine physicians visually interpreted both DAT and CBF images rating the severity into 4 grades (from 0 to 3). Totally 12 (6/hemisphere) supratentorial regions on the 99mTc-ECD images and 2 regions (left and right striatum) on the 123I-IFP were defined for each patient. The correlation of visual analysis results between GCA and SPICA was evaluated by weighted Kappa statistics. For quantitative analyses, we calculated the cerebrum-thalamus count ratio of 99mTc-ECD and the specific-to-background ratios of 123I-IFP. We assessed those regions of Pearson9s correlation coefficient and intraclass correlation coefficient (ICC) between the conventional scanner and the new system. Results The weighted Kappa statistics between GCA and SPICA were 0.67 and 0.68 for 99mTc-ECD and 123I-IFP, respectively, indicating high interrater reliability. The semi-quantitative analyses demonstrated that the 99mTc-ECD cerebrum-thalamus count ratio of SPICA was well correlated to GCA (R=0.81, p Conclusions The findings and quantitative results of both CBF and DAT images of dual isotope study with the new system had excellent correlation with those of single isotope studies with the conventional scanner with two separate days. In conclusion, our new SPECT scanner with semiconductor detectors enables quantitative dual tracer diagnostic imaging of CBF and Dopamine transporter imaging in patients with cognitive disorder. This technique may enable the one-stop imaging diagnosis for dementia and reduce the burden on patients.