C-PIB retention patterns in white and grey cerebral matter in idiopathic normal pressure hydrocephalus patients. A visual analysis.

Objective: Cortical cerebral amyloid disease, a hallmark of Alzheimer's disease, has also been observed in idiopathic normal pressure hydrocephalus (iNPH). The aim of this study was to compare the C-PIB PET/CT retention pattern in iNPH patients and healthy subjects.

Material And Methods: A comparison was made of the C-PIB PET/CT retention pattern in 13 iNPH patients selected for surgical deviation, compared to a normal control population. Images were visually analyzed and scored for gray matter and white matter (WM) from 1 to 4 (slight to very high PIB retention). The scoring was analyzed in both groups separately for infra- and supra-tentorial regions. A comprehensive clinical report was presented in terms of positive, negative, or equivocal.

Results: C-PIB PET/CT scan were reported as negative in 8, positive in 3, and equivocal in 2. Five of 13 patients showed at least one cortical area with PIB retention with an intensity higher than that observed in the control group. Overall, white matter (WM) PIB retention of iNPH scored lower than in the control group, showing a statistically significant difference in the infratentorial WM (92/104 vs 54/56; p<.05) and a tendency to be lower in the supratentorial regions (70/84 vs 122/156, p=.327), in particular in the upper periventricular region (25/28 vs 40/52; p=.134).

Conclusions: The PIB retention pattern seems to be different in NPH, compared to normal subjects. PIB retention in WM of NPH appears less intense than in healthy subjects, and they show a higher degree of PIB retention in cortical regions. This deserves to be taken it into account.