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

Abstract

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. We undertook this study to evaluate the role of visual analysis of SPECT perfusion patterns for the differential diagnosis of types of degenerative dementia. 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. 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. Tc-99m ECD brain perfusion SPECT is useful in the differential diagnosis of dementia with particular reference to AD as well as FTD.