Abstract
Standardized uptake value ratios (SUVR) are used for relative quantification of 18F-Florbetaben (FBB) scans. Cerebellar cortex can be used as reference region for quantification. However, cerebellar amyloid-beta (Aβ plaques may be present in Alzheimer disease (AD). The aim of this study was to assess the influence of Aβ pathology, including neuritic, diffuse plaques, and vascular deposits, in FBB SUVR, when using cerebellum as the reference. Methods: Neuropathological assessment of frontal, occipital, anterior and posterior cingulate cortices and cerebellar cortex from 87 end of life patients (64 AD, 14 other dementia, 9 non-demented aged volunteers; 80.4±10.2 yrs.) who underwent a FBB positron emission tomography (PET) before death was performed using immunohistochemistry for Aβ plaques and vascular deposits and the Bielschowsky method to demonstrate neuritic plaques. The lesions were rated as as absent (none, sparse) or present (moderate, frequent). Mean cortical SUVRs were compared among cases with different cerebellar Aβ loads. Results: None of the 83 evaluable cerebellar samples showed frequent diffuse Aβ or neuritic plaques, 8 samples showed frequent vascular Aβ deposits. Diffuse Aβ plaques were rated as absent in n = 78 samples (94%) and as present in n = 5 samples (6%). Vascular Aβ was rated as absent in 62 samples (74.7%) and as present in 21 samples (25.3%). No significant differences in the cerebellum SUVs were found among cases with different amounts or types of Aβ deposits in the cerebral cortex. Both diffuse and neuritic plaques were found in the cerebral cortex of 26-44 cases. No significant SUVR differences were found in these brains, which showed different cerebellar Aβ loads. Conclusion: The effect of cerebellar plaques in cortical FBB SUVRs appears to be negligible even in advanced stages of AD with a higher cerebellar Aβ load.
- Copyright © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.