IMPROVED QUANTIFICATION METHODS FOR BRAIN β-AMYLOID BURDEN ON 11C-PIB PET IN PATIENTS WITH ALZHEIMER'S DISEASE

Background: Virchow-Robin (perivascular) spaces are formed by the widened subarachnoid spaces around perforating arteries entering brain parenchyma. These are normally detected by microscopic examination, though they could easily be seen in cranial magnetic resonance imaging when enlarged. They are mostly asymptomatic; those localized in midbrain may cause obstructive hydrocephalus. Extremewidening of Virchow-Robin spaces, on the other hand, has been found to be related with aging, dementia, hypertension and other vascular risk factors, although there is an ongoing debatewhether these spaces may cause clinical symptoms, or not.Methods: Here we report a 50-year-old man complaining of progressive forgetfulness for two years. Results: He has trouble in managing financial accounts. He needs to keep notes to remember, but cant remember when he reads his notes. Neurological examination was normal with a mini mental state examination test of 29/30 points. Neuropsychological evaluation revealed mild impairments in frontal lobe functions, mild impairment in verbal memory, and mild-to-moderate impairment in visual memory. Cranial magnetic resonance imaging showed diffuse extreme widening of VirchowRobin spaces, being more prominent in left hemisphere (Figure 1a and 1b). Detailed laboratory tests excluded any other secondary causes of mild cognitive impairment / dementia. Figure 1a and 1b. Multiple subcortical cystic lesions isointense with cerebrospinal fluid in both T1and T2-weighted images aligned via penetrating arteries were diagnosed as extreme widening of Virchow-Robin spaces.Conclusions:Diffuse extreme widening of Virchow-Robin spaces are rarely reported in the literature. Although the causal relationship of these lesions with mild cognitive impairment or dementia is controversial; in the presented case, with the exclusion of other secondary causes, the localization of these cystic lesions was correlated with clinical symptoms and impairments observed in neuropsychological evaluation.