Hypoperfusion of the Left Insula, Operculum, and Putamen on Technetium-99m Ethyl Cysteinate Dimer (99mTc-ECD) Single-Photon Emission Computed Tomography in Patients With Mild Cognitive Impairment and Early Alzheimer's Disease.

Objective: The easy Z-score imaging system (eZIS) objectively interprets brain perfusion. Using eZIS-processed images, we observed decreased regional cerebral blood flow (rCBF) in the left putamen of several patients with forgetfulness. This study aimed to examine this decrease using statistical image analysis.

Methods: Cerebral perfusion single-photon emission computed tomography (SPECT) was performed on patients with mild cognitive impairment (MCI) and early Alzheimer's disease (AD). Normalized and corrected SPECT images were compared between patients and controls using Statistical Parametric Mapping software (SPM12, The Wellcome Center for Human Neuroimaging, UCL Queen Square Institute of Neurology, London, UK). Eigenvariate values of clusters with significantly low and high rCBF were obtained. Principal component analysis (PCA) was then used to examine the relationships among these clusters.

Results: We observed decreased rCBF in the left insula, operculum, and putamen, indicating that the reduction extended laterally from the initial eZIS-based findings. We obtained eight decreased and seven increased eigenvariate values for abnormal rCBF clusters. PCA revealed that the left insula, operculum, and putamen were the most influential principal components, along with the posterior cingulate and precuneus cortices. The eigenvariate values in these regions did not correlate with sex, diagnosis (AD or MCI), or cognitive scores.

Conclusions: We reported the decreased rCBF in the left insula, operculum, and putamen. However, its clinical significance beyond the associations with forgetfulness and its natural radiological course remains unclear.