The Influence Of Colour Scale In Lesion Detection And Patient-Based Sensitivity In [Ga-68]Ga-Psma-Pet/Ct

ObjectiveTo investigate the influence of colour scales on the interpretation of [Ga-68]Ga-PSMA-11 PET/CT for the diagnosis of recurrent prostate cancer.Methods50 consecutive patients who underwent [Ga-68]Ga-PSMA-11 PET/CT for recurrent prostate cancer were selected for this retrospective study. The scans were randomised, anonymised and read by five different readers first in the visually nonlinear colour scale 'PET-rainbow'. Scans were then rerandomised and read in the visually linear colour scale 'hot-metal new'. For each scan in each colour scale the numbers of pathological, equivocal and benign lesions were noted. Scans where the majority of readers (>= 3) reported at least one PET-positive lesion were recorded as 'pathological'. Patient-level sensitivity was obtained by composite standard with 14.8 +/- 1.2 months of follow-up.ResultsIncreased numbers of lesions per patient were reported for all readers in PET-rainbow compared to hot-metal new (37.4 +/- 15.2 vs. 33.9 +/- 16.4, respectively, P = 0.0005). On a per-patient basis, 43 scans were rated pathological in PET-rainbow, compared to 39 in hot-metal new. Follow-up was available for 30 patients confirming 26 pathological scans with positive follow-up in PET-rainbow, and 23 in hot-metal new. Three pathological scans were missed in hot-metal new. Patient-level sensitivity was higher for PET-rainbow (0.96) compared to hot-metal new (0.85). Inter-reader reliability was higher for hot-metal new (Fleiss kappa = 0.76) compared to PET-rainbow (Fleiss kappa = 0.60).ConclusionUse of PET-rainbow was associated with improved lesion detection and sensitivity compared to hot-metal new, although at cost of reduced inter-rater agreement. Consequently, the use of PET-rainbow for clinical routine and future studies involving [Ga-68]Ga-PSMA-11 is recommended.