Clinical Correlation and Metabolic Findings on 18F-Fluorodeoxyglucose Brain PET in Dementia With Lewy Bodies: A Case Report

Neurodegenerative dementias comprise a heterogeneous group of diseases with distinct pathological substrates, among which Alzheimer's disease, dementia with Lewy bodies (DLB), and frontotemporal dementia are the most prominent. The early and accurate diagnosis of these conditions remains a clinical challenge, in which both structural and functional imaging techniques play crucial roles. This article presents a case of a 68-year-old female patient with progressive cognitive decline, evaluated using ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET), which revealed a characteristic pattern of symmetric hypometabolism in the temporal, parietal, and occipital lobes, with preserved metabolism in the posterior cingulate cortex (the cingulate island sign), a finding highly suggestive of DLB. This case highlights the value of ¹⁸F-FDG PET as a diagnostic tool in the differential evaluation of dementias and underscores the importance of recognizing the specific metabolic pattern of DLB to support timely clinical decision-making. The model incorporating visual and semi-quantitative parameters achieved a diagnostic accuracy of 84.3%.