Tc-99m ethylcysteinate dimer SPECT in the differential diagnosis of dementias

Background: Dementias produce deficits in perfusion, in part, reflecting decreased metabolic needs. Single photon emission computed tomography (SPECT) studies have reported characteristic anterior-to-posterior perfusion gradients that permit distinction between the various forms of dementia. Aim: We undertook this study to evaluate the role of visual analysis of SPECT perfusion patterns for the differential diagnosis of types of degenerative dementia. Materials and Methods: Tc-99m ethylcysteinate dimer (ECD) was used with a dual-head scanner to generate perfusion images of the brain in 136 patients referred from the dementia clinic. Diagnosis was made by the nuclear physician unaware of clinical diagnosis. Results: Sensitivity, specificity, positive predictive value and negative predictive value of perfusion studies for Alzheimer's dementia were 93.42%, 95.12%, 97.26%, and 88.63%, respectively, and for frontotemporal dementia were 96.29%, 98%, 96.29%, and 98.88%, respectively. Conclusions: Tc-99m ECD brain perfusion SPECT is useful in the differential diagnosis of dementia with particular reference to AD as well as FTD.