Head-To-Head Comparison of ⁶⁸Ga-PSMA-11 PET/CT and ^99mTc-MDP Bone Scintigraphy for the Detection of Bone Metastases in Patients With Prostate Cancer: A Meta-Analysis.

Abstract

<b>BACKGROUND.</b> Bone scintigraphy (BS) using ^99mTc-labeled methylene diphospho-nate (^99mTc-MDP) remains the recommended imaging modality for the detection of bone metastases in patients with prostate cancer (PCa). However, PET/CT using prostate-specific membrane antigen (PSMA) ligands is increasingly recognized as a means of evaluating disease extent in patients with PCa, including use as a possible stand-alone test in high-risk patients. <b>OBJECTIVE.</b> The purpose of this study is to compare the diagnostic performance of ⁶⁸Ga-PSMA-11 PET/CT with that of ^99mTc-MDP BS for the detection of bone metastases in patients with PCa. <b>EVIDENCE ACQUISITION.</b> The PubMed, Embase, and Cochrane Library databases were searched through October 2021 to identify studies reporting a head-to-head comparison of ⁶⁸Ga-PSMA-11 PET/CT and ^99mTc-MDP BS for the detection of bone metastases in patients with PCa. Only studies with a well-defined reference standard (including various combinations of imaging and/or clinical follow-up) were included. Pooled diagnostic performance was calculated using a bivariate random-effects model, and an AUC was derived for each test from hierarchic summary ROC analysis. The complementary roles of the two tests in identifying bone metastases in patients in whom one of the tests was negative were summarized. <b>EVIDENCE SYNTHESIS.</b> Six studies with 546 patients were included. Pooled sensitivity and specificity, respectively, were 98% (95% CI, 94-99%) and 97% (95% CI, 91-99%) for ⁶⁸Ga-PSMA-11 PET/CT versus 83% (95% CI, 69-91%) and 68% (95% CI, 41-87%) for ^99mTc-MDP BS. The AUC was 0.99 (95% CI, 0.96-1.00) for ⁶⁸Ga-PSMA-11 PET/CT and 0.85 (95% CI, 0.81-0.87) for ^99mTc-MDP BS. Among 408 patients from five included studies, ⁶⁸Ga-PSMA-11 PET/CT correctly identified bone metastases in 43 of 193 patients (22.3%) with negative ^99mTc-MDP BS results, whereas ^99mTc-MDP BS correctly identified bone metastases in four of 210 patients (1.9%) with negative ⁶⁸Ga-PSMA-11 PET/CT results. <b>CONCLUSION.</b> On a per-patient basis, the diagnostic performance of ⁶⁸Ga-PSMA-11 PET/CT is superior to that of ^99mTc-MDP BS for the detection of PCa bone metastases. Furthermore, ^99mTc-MDP BS offers limited additional information in patients with negative ⁶⁸Ga-PSMA-11 PET/CT results. <b>CLINICAL IMPACT.</b> According to current evidence, ^99mTc-MDP BS is highly unlikely to be additive to ⁶⁸Ga-PSMA-11 PET/CT in identifying bone metastases in patients with PCa.