Assessment of diffuse Lewy body disease by 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET)

Five patients (5 m, mean age 75 y) with clinically suspected diffuse Lewy body disease (DLB) were studied with FDG PET. PET studies of the head were performed with a Siemens ECAT-ART PET-scanner with attenuation correction using 137-Cs point sources.We found the same distribution pattern of diffuse glucose hypometabolism in the entire cortical region with relative sparing of the primary sensory-motor cortex in all the patients. The few cases reported in the literature so far describe findings similar to ours.The pattern of diffuse glucose hypometabolism in the entire cortex including the occipital region seems to be a typical feature of DLB that is distinctive from dementia of Alzheimer's disease.Dementia with Lewy bodies (DLB) has been established as the second most common senile degenerative dementia after Alzheimer's disease (AD) [1-3]. Lewy bodies, first described in 1912 by F.H. Lewy are distinctive neuronal inclusions that may be seen in several different neurodegenerative processes [4]. Lewy bodies are eosinophilic structures located within the cytoplasm of neurons. They are characteristically circular with a dense protein core surrounded by a peripheral halo. They are thought to be the result of altered neurofilament metabolism and/or transport due to neuronal damage and subsequent degeneration, causing an accumulation of altered cytoskeletal elements. 5–10% of asymptomatic individuals have presumably insignificant numbers of Lewy bodies, usually located in the substantia nigra. [5]. Diagnostic criteria for DLB have been defined to allow clinical diagnosis [3]. Until quite recently, post mortem examination provided the definitive diagnosis. However, while these clinical criteria have high specificity (90–97%), they have low sensitivity (22–75%) [6]. The central clinical feature required for a diagnosis of DLB is a progressive and fluctuating cognitive decline with recurrent visual hallucinations, systematized delusions and spontaneous parkinsonian symptoms.