Abstract
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Introduction: β-Amyloid (Aβ) neuroimaging plays a vital role in in vivo detection of Aβ accumulation in patients with cognitive impairment consistent with Alzheimer’s disease. Qualitative adjudication of Aβ positivityf is an art that could be facilitated by relying on results from semi-quantitative Z-score analysis, a process that may be beneficial to trainees and inexperienced or infrequent readers. Materials and Methods: We conducted a retrospective review of [F18]-florbetaben PET/CT studies acquired at our institution from June 2016-May 2018. Visual interpretation to determine Aβ+ status was conducted by two independent readers blinded to each other’s interpretation. Afterwards, scans were post-processed utilizing MIMneuro software, which generated regional-based semiquantitative Z-scores indicating cortical amyloid burden, with cerebellum as the reference region.
Results: Fifty [F18]-florbetaben PET/CT studies were obtained (26 females, 24 males; mean age 75.7 ± 6.7 years). Upon visual assessment, 34 of 50 (reader 1) and 36 of 50 scans (reader 2) scans were considered positive for increased amyloid deposition. The largest semi-quantitative differences were identified in the left frontal lobe (Z = 7.70 in Aβ+ versus 0.30 in Aβ- subjects). However, all unilateral regions showed large statistically significant differences in Aβ burden (P≤9.5E-08 in all cases). Semi-quantitative scores were highly sensitive to Aβ+ status and highly accurate in their ability to identify amyloid-positive status. Conclusion: Visual assessment and semiquantitative Z-score analysis provide highly congruent results, thereby enhancing reader confidence and improving scan interpretation. This is particularly relevant given the recent emphasis on amyloid-targeting disease modifying therapeutics, as they emerge from the research setting and enter clinical practice. References:1. Becker GA, Ichise M, Barthel H, Luthardt J, Patt M, Seese A, Schultze-Mosgau M, Rohde B, Gertz HJ, Reininger C, Sabri O. PET quantification of 18F-florbetaben binding to β-amyloid deposits in human brains. J Nucl Med. 2013 May;54(5):723-31. 2. Ishii, K., Yamada, T., Hanaoka, K. et al. Regional gray matter-dedicated SUVR with 3D-MRI detects positive amyloid deposits in equivocal amyloid PET images. Ann Nucl Med 34, 856-863 (2020). https://doi.org/10.1007/s12149-020-01513-33. Akamatsu, G., Ikari, Y., Ohnishi, A. et al. Voxel-based statistical analysis and quantification of amyloid PET in the Japanese Alzheimer’s disease neuroimaging initiative (J-ADNI) multi-center study. EJNMMI Res 9, 91 (2019). https://doi.org/10.1186/s13550-019-0561-2 binding to β-amyloid deposits in human brains. J Nucl Med. 2013 May;54(5):723-31.