J Nucl Med. 2008; 49 (Supplement 1):227P
Neurosciences: NeurologyNeurology Posters |
Quantitative analysis of basal ganglia metabolism in encephalitis lethargica
Mike Georgiou1,
Russ Kuker1,
Spyridon Papapetropoulos2,
Roberto Lopez-Alberola2 and
George Sfakianakis1
1 Nuclear Medicine;
2 Neurology, University of Miami, Miami, Florida
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Objectives: Encephalitis lethargica (EL) is a rare CNS disorder characterized by lethargy, sleep cycle disturbances, extrapyramidal symptoms and neuropsychiatric manifestations. The etiology of EL is unclear but the possible role of autoimmunity has been suggested after the discovery of anti-basal ganglia (ABG) antibodies in sera. Our goal was to quantitate regional differences in cerebral metabolism on FDG-PET in EL patients, with focused analysis of the basal ganglia.
Methods: Nine FDG-PET brain scans were performed on five patients with clinical suspicion of EL. NeuroQ (Syntermed, Inc) software was employed to quantitate the relative activity in 240 standardized brain regions of interest. Normalized counts per pixel were extracted for the basal ganglia [caudate (CN) and lentiform (LN) nuclei] and cerebral cortex and then compared to a database of asymptomatic controls to evaluate for statistical significance.
Results: In 4/5 patients, there was relative hypermetabolism in the LN. This was evidenced by a greater than two standard deviation increase in LN activity as compared to asymptomatic controls and a ratio of activity in LN to the cerebral cortex (LN/C ratio) greater than 1.3. In addition, a serial increase in LN activity was observed in 3/4 patients who had follow-up scans indicating there may be temporal effects of the disease process on LN.
Conclusions: LN (and not CN) hypermetabolism demonstrated by quantitative analysis of FDG-PET aides the diagnosis of EL and may provide insight into the pathophysiology of the disease.
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Basal Ganglia vs. Cerebral Cortex Activity
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