Intraobserver and interobserver agreement for the interpretation of 68Ga–prostate-specific membrane antigen-I&T positron emission tomography/computed tomography imaging

OBJECTIVES: The use of Ga-prostate-specific membrane antigen positron emission tomography/computed tomography is spreading due to its clinical benefits. In this study, we aim to determine the intra- and interobserver agreement levels of Ga- prostate-specific membrane antigen-I&T positron emission tomography/computed tomography according to molecular imaging tumor-lymph node-metastases reporting system. MATERIALS AND METHODS: Eighty prostate cancer patients and underwent Ga- prostate-specific membrane antigen positron emission tomography/computed tomography were blindly evaluated twice by four nuclear medicine specialists at intervals of 4 weeks. The evaluations were performed according to molecular imaging tumour-lymph node-metastases (miTNM) classification. We used Cohen's Kappa and Fleiss' Kappa analysis to analyse intra- and interobserver agreements. RESULTS: When Ga-prostate-specific membrane antigen positron emission tomography/computed tomography findings were evaluated according to miTNM classification, the obtained kappa values were as follows. The intraobserver Cohen's kappa coefficient was found to be 0.79 (substantial agreement), 0.93 (almost perfect agreement), and 0.94 (almost perfect agreement) for miT, miN, and miM, respectively. During interobserver evaluation between the four observers, the kappa coefficient was 0.52 (moderate agreement) for miT, 0.74 (substantial agreement) for miN, and 0.84 (almost perfect agreement) for miM. CONCLUSION: There is no research on the intraobserver agreement analysis of Ga-prostate-specific membrane antigen positron emission tomography/computed tomography in the literature. Our findings are the first ones. The intraobserver agreement was almost perfect. Moreover, although Ga-prostate-specific membrane antigen I&T positron emission tomography/computed tomography had moderate interobserver evaluation compliance of the primary tumour, it had excellent interobserver agreement levels in local lymph node metastasis and distant metastasis evaluation.4012501255.