Quantitative brain dual isotope study using Tc-99m HSAD and I-123 IMP with dual head semiconductor detector SPECT system

Objectives We developed a prototype CdTe SPECT system with 4-Pixel Matched Collimator (4PMC) for brain study. This system provides high enegy resolution (6.6%), high sensitivity and high spatial resolution images. The aim of this study is to evaluate dual isotope study of cerebral brood volume (CBV) and cerebral blood flow (CBF) images using Tc-99m HSAD and I-123 IMP with the new SPECT system.

Methods This study included five normal volunteers. CBV images were acquired 5 minite after Tc-99m HSAD injection for 20 minutes (Single acquition). After CBV image acquition, I-123 IMP was injected intravenously and CBF and CBV images were aquired simultaneously 20 minute after IMP injection (Dual acquition). Because of high energy resolution and higher I-123 enegy peak, Tc-99m study did not influence I-123 study with phantom study. CBV images were compared using D/S ratio determined as the ratio of cerebral HSA-D counts on Dual acquisition to those on Single acquisition. The nuclear physicians visually inspected the CBV images (Single and Dual acqution) and evaluated the image quality by 5 points visual scoring (1=poor to 5= excellent).

Results The means of D/Ss were 0.967+0.05. The image quality of CBV were concordant in all volunteers on CBV iamges between Single and Dual acquisition and the mean of visual score was 5. The means of CBF image visul score were 4.6+0.54(mean+ S.D).

Conclusions Our new SPECT system with semiconductor detector could provide quantitaive and highquality brain perfusion images and cerebral blood volume images simaltanuousely. Semiconductor detector SPECT system will permit quantitative Tc-99m and I-123 dual isotope study.