Fig. 4
From: Post-mortem histopathology underlying β-amyloid PET imaging following flutemetamol F 18 injection
Inter-reader agreement and reader confidence are decreased in cases with a plaque burden close to the threshold of PET detection. Panel a shows inter-reader agreement across the spectrum of mCERADSOT scores with values lowest about the 1.5 threshold. The transition from amyloid phase 2 to phase 3 is associated with neocortical plaque burden between sparse and moderate (see Fig. 4) and both inter-reader agreement (Panel b) and reader confidence (Panel c) is lowest in phase 3 (P < 0.001 for both data sets, Kruskal Wallis test). Inter-reader agreement was determined as Fleiss’ kappa coefficient P i (see text for details) and for 5 readers is 1 when all 5 readers are in agreement, 0.6 when the agreement is 4:1 and 0.4 when the agreement is split 3:2. Confidence was recorded as a 5 point scale (1–5) with 5 being most certain and 1 being the least certain. For all panels, boxes represent mean +/- 1 standard error and whiskers represent 95% confidence interval. Open circles represent outlier values and asterisks represent extreme values (see Materials and methods for details)