In vivo Amyloid Plaques Quantification using F18-Flutemetamol in 30 Healthy Elderly Controls and 62 MCI patients: SUVr comparison between PMOD 3.2 and PNEURO 3.5 analysis.

515 Objectives Although visual analysis of Amyloid PET has been considered sufficient to discriminate Alzheimer’s patients from healthy elderly subjects, early stage of the degenerative process (MCI stade), exhibiting fewer amyloid deposits, may be more challenging to interpret. In this situation, a robust quantitative analysis may not only be helpful to reinforce the visual analysis but also to allow longitudinal evaluation of the amyloid load in this population. Methods As part of a academic study evaluating the impact of biomarkers to stratify MCI patients, 30 healthy controls (70±5.5 y) and 62 (70.8±8.0 y) patients presenting Mild Cognitive Impairement (MCI) were imaged 90 min PI with F18-Flutemetamol scan (GE Healthcare; target ID 185 MBq). SUVr (neocortex/cerebellum) values computed with step-by-step analysis based on several PMOD 3.2 tools (see previously published data) were compared to those obtained with a more recent evolution of the PMOD software (PNEURO 3.5) implementing several useful improvements for clinical translation (semi-automatic workflow, more accurate MRI segmentation for VOI delineation⋯). However, those methodological changes could also potentially influence the results, reason why a front-to-front comparison was performed. Results PMOD 3.2 and PNEURO 3.5 SUVr (Mean±SD/Median/PC90) of the control group were respectively 1.40±0.23/1.33/1.69 and 1.29±0.16/1.26/1.49, both significantly different from the MCI group analysis (1.67±0.39/1.57(P=0.002) and 1.55±0.35/1.42 (p<0.0001)). Despite a good correlation (r2: 0.95), pooled SUVr PNEURO 3.5 values were significantly lower than the previously computed PMOD 3.2 values (P< 0.0001; bias(d): -0.12, SD of bias: 0.09; 95% limits of agreement: from -0.29 to 0.06). The SUVmean of the cerebellar region of reference (Mean±SD/Median) was not statistically different between controls and MCI: 0.59±0.15/0.59 vs 0.63±0.15/0.61 (P=0.28) for PMOD 3.2 and 0.63±0.14/0.64 vs 0.67±0.14/0.65 (P=0.42) for PNEURO 3.5. However, a significant difference was observed (P Conclusions SUVr computation based of PNEURO 3.5 seems a easy way to quantify the neocortical amyloid load in MCI patients, providing similar results than the visual scan reading but with the advantage to be independent of the physician’s degree of expertise.