Comparison of Different Quantitative Methods and Visual Evaluation on the Tc-99m-HMPAO Brain Perfusion SPET

Objectives Brain perfusion SPECT has been widely used for evaluation of brain perfusion and metabolic status. We aimed to compare different quantitative methods on Tc-99m-HMPAO SPET based on visual evaluation. Materials and Methods: Forty-seven patients were enrolled in this comparative study. Tc-99m-HMPAO brain SPET was performed. For semiquantitative analysis, two orbitomeatal (OM) composite slices were obtained. Regional cerebral perfusion data were semi-quantitatively computed by the ratio between each cerebral ROI mean-counts and the reference region mean-counts. Mean counts of the cerebellum, mean-counts of lower OM slice and contralateral ROI mean-counts were used as reference regions. Two different nuclear physicians evaluated all images. It was considered 0 (=hypoperfusion area); 1 (=normal perfusion area) and 2 (=hyperperfusion area) by visual evaluation. SPET slice’s region of interest (ROI) data were analyzed by receiver operator characteristics (ROC) method to establish the optimal decision threshold for different quantitative methods. Results: Our results observed that usage of small ROIs were better than larger ones. The mean-counts of lower OM slice had a positive correlation with the cerebellum mean-count. Additionally, as reference regions, mean-counts of lower OM slice was slightly better than cerebellum and evidently better than symmetric region of the contralateral hemisphere. Conclusion: We did not found the expected high correlation among visual analysis and these quantitative methods. We believe that new quantitative methods on the Tc-99m-HMPAO brain perfusion SPET are required. ©2006, Fırat Üniversitesi, Tıp Fakültesi