Diagnostic value of 18F-FDG PET and 11C-PIB PET on early stage posterior cortical atrophy

Abstract

Background  Posterior cortical atrophy (PCA) is a kind of progressive neurodegenerative disease with cortical visual impairment as the first symptom. Because of rare clinical incidence, early onset age, special clinical symptoms and unobvious MRI abnormality, the definitive diagnosis of PCA is difficult. This study used ¹⁸F-fluoro-2-deoxy-D-glucose (¹⁸F-FDG) PET and ¹¹C-Pittsburgh compound B (¹¹C-PIB) PET for PCA patients with unobvious MRI abnormality, so as to discuss the value of PET in the early diagnosis of PCA.  Methods  Five patients diagnosed as PCA in our hospital between April 2012 and March 2015 were enrolled in this study. Cognitive function was measured by Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Activities of Daily Living (ADL) and Clock Drawing Test (CDT). Brain MRI, ¹⁸F-FDG PET and ¹¹C-PIB PET were performed to analyze glucose metabolism and perfusion of posterior cortex.  Results Neuropsychological tests revealed that the ability of writing, calculating, visuospatial and executive function of all these patients were impaired. Color vision tests showed abnormal results. MRI showed that the posterior atrophy (PA) scores were 0-2 (average 1) on the left side and 0-1 (average 0.80) on the right side. The medial temporal atrophy (MTA) scores were 1-3 (average 1.80) on the left side and 1-4 (average 2) on the right side. The ventricular enlargement (VE) scores were 1-2 (average 1.80) on the left side and 1-2 (average 1.60) on the right side. ¹⁸F-FDG PET showed glucose metabolism decreased obviously on bilateral temporo-parieto-occipital cortex, precuneus and cingulate gyrus, and slightly on frontal lobes and subcortical structure. ¹¹C-PIB PET showed radioactive ¹¹C-PIB deposition on bilateral frontal, temporal, parietal and occipital cortex, and the outline of cerebellar cortex was clear.  Conclusions  For PCA patients whose parietal and occipital cortical atrophy is not obvious on MRI, ¹⁸F-FDG PET combined with ¹¹C-PIB PET plays an important role in early diagnosis.

DOI: 10.3969/j.issn.1672-6731.2015.08.005