Role of PET-CT in Aiding Diagnosis of Various Neurological Conditions – A Case Series

Abstract

BACKGROUND PET-CT is an imaging modality which electronically detects positron-emitting radiopharmaceuticals in the human body and reveals its exact anatomical location.1 PET CT measures the metabolic and functional activity of living tissue noninvasively.1 This technology is utilized in diagnosis, planning treatment and predicting outcomes in various neurological conditions.1 Depending upon various patterns of FDG uptake in different parts of brain, 18FDG PET-CT allows us to differentiate between various types of dementia.2 PET CT allows tracking the course of disease and revealing the severity of the disease.2 In this article, we discuss the imaging findings of normal 18 FDG PET-CT of brain and 8 different neurological conditions with their corresponding brain PET-CT findings. METHODS To study the role of 18FDG-PET/CT in neurological conditions, we identified 8 different patients who underwent 18FDG-PET/CT imaging of brain for clinically suspected different neurological diseases at Department of Radiodiagnosis-Centre of Excellence (CERIS), SRIHER, Chennai, between 2015 and 2019. Siemens Biograph Horizon 16-slice PET/CT scanner with TrueV was used. Syngo.Via Version VB30A software was used. 18F- Fluorodeoxyglucose was the radiotracer used [Dose: 3-7 mCi]. After the scan, different patterns of 18 FDG uptake in the brain were analyzed in each of these patients. RESULTS 18 FDG PET-CT showed reduced uptake in the epileptogenic foci in the brain. Alzheimer’s disease showed decreased FDG uptake in bilateral precuneus, posterior cingulate region, parietal cortex and frontal cortex. Fronto-temporal dementia revealed reduced FDG uptake in anterior cingulate gyrus and anterior temporal lobe. Primary progressive aphasia showed asymmetrical reduced metabolic activity in the bilateral frontal and temporal lobes. Progressive supranuclear palsy revealed reduced metabolic activity in bilateral paramedian frontal region, head of caudate nuclei and midbrain; Multi systemic atrophy showed reduced metabolic activity in midbrain, pons, medulla oblongata and the cerebellum; AIDS related dementia showed global hypometabolism with preserved uptake in basal ganglia. CONCLUSIONS 18FDG-PET/CT has a vital complementary role in the evaluation CNS disorders along with clinical examination, other imaging modalities like CT, MRI, and electroencephalogram (EEG). Radiologists should be aware of these different patterns of FDG uptake to aid the clinical diagnosis and early treatment. KEY WORDS 18 FDG PET-CT, 18FDG Uptake, Hypometabolism, PET-CT Brain