Peak-clearance-rate as index for detection of Alzheimer’s disease using 11C-PiB PET imaging

Abstract

Amyloid-beta imaging with 11C-PiB shows a robust increase in cortical binding in Alzheimer’s Disease (AD). Standardized uptake value ratio (SUVR) and distribution volume ratio (DVR) were shown to be effective quantitative measures in discriminating healthy and AD subjects. However, these measures typically require long wait/scan time and optimal selection of the reference region. The aim of this study is to propose a novel measure, which has superior diagnostic performance than conventional measures and has a less complicate scan workflow. We used ¹¹C-PiB datasets that is publicly available from OASIS project. A total number of 50 dynamic scans are included in this study, of which 25 are from AD and 25 are from heathy control (HC) subjects. For all subjects, we first quantified standardized uptake value ratio (SUVR, 50-60 mins) and distribution volume ratio (DVR, T*=30 min) in frontal cortex region. Reference region was selected as whole cerebellum. We then defined a new measure, Peak-Clearance-Rate (PCR) which calculated the uptake decay rate in early stage of the scan (from the peak uptake time to 20 min). The new measure, SUVR and DVR all can differentiate the HC and AD subjects (p<0.05). ROC analysis was performed and indicated that PCR has better performance (AUC=0.912) than DVR (AUC=0.846) and SUVR (AUC=0.843). Cohen’s size for PCR is 2.53, while the ones for SUVR and DVR are 1.79 and 1.75. The proposed measure is an alternate measure of diagnosis in AD with ¹¹C-PiB imaging. Additionally, it only requires first 20-min scan and does not require the procedure of delineation of reference tissue region. Further investigation will focus on staging, specifically in differentiating mild cognitive impairment (MCI) subjects from aged healthy and AD subjects.