Quantitative evaluation of beta-amyloid brain PET imaging in dementia: a comparison between two commercial software packages and the clinical report.

OBJECTIVE: To compare commercially available image analysis tools Hermes BRASS and Siemens Syngo.VIA with clinical assessment in 18F-Florbetapir PET scans. METHODS: 225 scans were reported by clinicians and quantified using two software packages. Scans were classified into Type A (typical features) or non-Type A (atypical features) for both positive and negative scans. For BRASS, scans with z-score ≥ 2 in 2 ≥ region of interest were classed positive. For Syngo.VIA a positive scan was indicated when mean cortical standardized uptake value ratio (mcSUVR) ≥ 1.17. RESULTS: 81% scans were Type A, and 19% scans were non-Type A. The sensitivity of BRASS and Syngo.VIA for Type A scans was 98.8 and 96.3%, specificity was 73 and 92%, respectively. Sensitivity for non-Type A scans was 95.8 and 79.2%, specificity was 36.8 and 57.9%, respectively.A third threshold of identifiable levels of plaque (1.08 ≤ mcSUVR ≤ 1.17) was recommended for Syngo.VIA to increase detection of false negative scans.The false positive rate of BRASS significantly decreased when an alternative positive threshold value of mcSUVR ≥ 1.18.Introduction of alternative criteria did not improve prediction outcome for non-Type A scans. More complex solutions are recommended. CONCLUSION: Hermes criteria for a positive scan leads to a high sensitivity but a low specificity. Siemens Syngo.VIA criteria gives a high sensitivity and specificity and agrees better with the clinical report. Alternative thresholds and classifications may help to improve agreement with the clinical report. ADVANCES IN KNOWLEDGE: Software packages may assist with clinical reporting of more difficult to interpret cases that require a more experienced read.