Abstract
Corticobasal degeneration (CBD) is a rare neurodegenerative disorder presenting with
atypical parkinsonian symptoms that characteristically involves the frontoparietal
region including the primary sensorimotor cortex, ipsilateral basal ganglia, and thalamus,
typically in an asymmetric pattern. We aim to evaluate the metabolic and volumetric
abnormalities in patients with clinically suspected CBD phenotypes utilizing hybrid
18F-fluorodeoxyglucose (FDG) positron emission tomography–magnetic resonance (PET/MR)
brain imaging. A retrospective analysis was performed on 75 patients (mean age 74
years, 31 males and 44 females) who underwent 18F-FDG PET/MR imaging (MRI) as part of their clinical dementia workup. Images were
obtained using an integrated Siemens mMR 3T PET/MRI scanner. Two board-certified neuroradiologists
and a nuclear medicine physician evaluated the metabolic and volumetric data of each
hemisphere to assess for symmetric or asymmetric involvement of regions of interest
in the subset of patients with suspected CBD. Of the 75 patients, 12 were diagnosed
with suspected CBD based on a combination of clinical symptoms, neurocognitive testing,
and hybrid neuroimaging findings. Ten of 12 patients (87%) demonstrated asymmetrically
decreased FDG uptake involving a single cerebral hemisphere and ipsilateral subcortical
structures, whereas two of 12 patients (13%) demonstrated striking hypometabolism
of the bilateral sensorimotor cortices. Our study highlights two characteristic patterns
of hypometabolism in patients with clinical and neuroimaging findings suggestive of
the underlying CBD. The first pattern is asymmetric hypometabolism and volume loss,
particularly within the frontoparietal and occipital cortices with involvement of
ipsilateral subcortical structures, including the basal ganglia and thalamus. The
second, more atypical pattern, is symmetric hypometabolism with striking involvement
of the bilateral sensorimotor cortices.
Keywords
Corticobasal degeneration - fluorodeoxyglucose - hybrid neuroimaging - positron emission
tomography - magnetic resonance imaging