Interobserver and intraobserver agreement for equivocal lesions in Ga-68 PSMA PET/CT according to PSMA-RADS 2.0 criteria
摘要
This study aims to systematically evaluate the inter- and intra-observer agreement regarding lesions with uncertain malignancy potential in Ga-68 PSMA PET/CT imaging of prostate cancer patients, utilizing the PSMA-RADS 2.0 classification system, and to emphasize the malignancy evidence associated with these lesions.
MethodsWe retrospectively reviewed Ga-68 PSMA PET/CT images of patients diagnosed with prostate cancer via histopathology between December 2016 and November 2023. Seventy-six patients and 98 target lesions, classified with PSMA-RADS scores 3A–3D by an experienced nuclear medicine specialist, were included. Three observers (two experienced and one less experienced nuclear medicine physician) evaluated the lesions at two different time points, three months apart, in a blinded manner. Intra-observer agreement was assessed using Cohen’s kappa, while inter-observer agreement was analyzed using Fleiss’ kappa.
ResultsAll observers demonstrated significant intra-observer agreement, with percentages ranging from 67.3 to 80.6% and kappa values between 0.62 and 0.76. The highest intra-observer agreement was noted for bone lesions, while non-regional lymph nodes exhibited the lowest agreement. For inter-observer assessments, moderate agreement was observed across all lesions (Fleiss k = 0.51), with the highest agreement in regional lymph nodes and the lowest in non-regional lymph nodes and bone lesions. Follow-up results indicated malignancy detection rates of 63.4% for 3A, 47% for 3B, 44.5% for 3C, and 41.4% for 3D scored lesions.
ConclusionsThe PSMA-RADS classification system demonstrated substantial intra-observer agreement and moderate inter-observer agreement for lesions with uncertain malignancy potential, supporting its clinical applicability. However, notable variability and limitations in reporting bone lesions, non-regional lymph nodes, and lung lesions were observed among readers. The ambiguous nature and management of PSMA-RADS 3 lesions underscore the need for further research to enhance risk stratification.