Comparing the role of 99mTc-HYNIC-PSMA-11 and 99mTc-MDP scintigraphy for the initial staging of intermediate to high-risk prostate cancer

Background Although bone scintigraphy and abdominopelvic computed tomography (CT)/MRI have been the mainstay of initial staging in the intermediate to high-risk prostate cancer (PC) patients, prostate-specific membrane antigen (PSMA) PET/CT imaging provides promising additional value in the initial N/M staging of these patients in recent years. Tc-99m-PSMA scan is a new alternative to PSMA PET tracers with little evidence regarding its diagnostic value in the initial staging of PC. Methods This prospective study included 40 patients with newly diagnosed PC with initial intermediate or highrisk features [prostate-specific antigen (PSA) > 10 ng/ dl, Gleason score =7 or stage cT2b and more]. All patients underwent both Tc-99m-methylene diphosphonate (MDP) bone scan and Tc-99m-HYNIC-PSMA-11 scan with maximum interval of 2 weeks. Abdominopelvic CT and MRI were also performed in this timeframe. Then, the results of these methods were compared with the final diagnosis data. Results Among the 40 included patients, 28 patients had finally been diagnosed as localized PC and 12 patients showed lymph node or metastatic involvement. The sensitivity, specificity and accuracy of Tc-99m-HYNICPSMA-11 vs. Tc-99m-MDP were 83.3% vs. 50.0%, 100% vs. 82.1% and 95% vs. 72.5%, respectively. However, when combined with the results of abdominopelvic CT/MRI the sensitivity reached 100% for both and the specificity raised to 100% and 96.4% for Tc-99m-HYNIC-PSMA-11 and Tc-99m-MDP, respectively. Conclusion Tc-99m-HYNIC-PSMA-11 performs well in the initial staging of intermediate to high-risk PC and especially in low source areas without PET/CT it can be used as the first-line method of metastatic evaluation instead of bone scintigraphy. However, the combination and correlation of cross-sectional imaging is essential to gain the optimal diagnostic value. Nucl Med Commun 44: 864-869 Copyright (c) 2023 Wolters Kluwer Health, Inc. All rights reserved.