In Differential Diagnosis of Dementia Application of Easy Z-score Imaging System in Single Photon Emission Computed Tomography Brain Perfusion Scan

Abstract

Application of easy Z score imaging system (eZIS) on brain perfusion SPECT images for quantitative evaluation of rCBF has attempted to explore the differential diagnosis of dementia with various degenerative diseases and to evaluate discrimination of early Alzheimer’s disease (AD) from other types of dementia. This retrospective study was done with various degenerative diseases that underwent brain perfusion SPECT using 99mTc ethyl cysteinate dimer were included. Brain perfusion SPECT was performed in 58 patients (M/F = 48/10) with mean age of 61.2±10.4 years (41-90). Decreased rCBF was observed in the area suspected early AD in 20 cases (34%) and in the frontal gyrus and insula in 10 cases (17%). And decreased rCBF was observed in occipital lobe and, precuneus, gyrus and posterior cingulate cortex in 8 cases (14%). Discrete areas of decreased rCBF were seen in 14 cases (24%) and the rest of 6 cases (11%) showed normal rCBF. Clinically suspected AD patients were divided into two groups on basis of MMSE score (group A, mild stage of AD, MMSE =20-26 and group B, moderate to severe stage of AD, MMSE=10-19). Mean MMSE and mean Z scores were 22.9±1.11 and 1.01±0.35 in group A (n = 12) while 17.56±0.96 and 2.62±0.59 in group B (n= 8). There was negative correlation between MMSE and eZIS score; r = - 0.69 in group A (p = 0.002); r = - 0.58 in group B (p = 0.019) and r = - 0.93 overall (p = 0.000). Quantification of rCBF with eZIS score was well associated with clinical MMSE scoring in this study group with clinical likelihood of having AD. In rest of the cases, SPECT findings and surface view analysis by eZIS, the affected area of decreased rCBF were consistent with clinically suspected different types of degenerative disease manifesting dementia.