Comparison of 68Ga-PSMA PET/CT and multiparametric MRI for the detection of low- and intermediate-risk prostate cancer

Abstract

Purpose To assess 68Ga-PSMA PET/CT for detection of low- and intermediate-risk prostate cancer (PCa), high-risk PCa in comparison with mpMRI, respectively, and to determine which of low- and intermediate-risk PCa are more likely to be detected by 68Ga-PSMA PET/CT. Methods We conducted a retrospective analysis of patients who had undergone a prostate biopsy and/or radical prostatectomy and who were scanned with 68Ga-PSMA PET/CT and mpMRI between June 2019 and March 2021. The mpMRI images were scored with the Prostate Imaging-Reporting and Data System Version 2.1 (PI-RADS) and were classified as either negative (PI-RADS 1–3) or positive (PI-RADS 4–5). Suspicious 68Ga-PSMA PET/CT lesions were reviewed for each relevant patient and classified by double-trained board-certified nuclear medicine physicians. The results were evaluated with the histopathological outcome. All patients were classified according to the D’Amico classification, and the clinical data were combined for stratified analysis. Result A total of 101 patients who were pathologically diagnosed with PCa were analyzed. Of the 101 patients, 88 (80.6%) patients presented with a pathologic mpMRI, and 85 (79.1%) with a pathologic 68Ga-PSMA PET/CT. In the high-risk PCa cohort, 68Ga-PSMA PET/CT was positive in 64/66 (97.0%) patients and yielded a higher detection rate than that for the mpMRI patients (58/66, 87.9%; p < 0.05). However, mpMRI provided superior diagnostic confidence in identifying low- and intermediate-risk PCa (30/35, 85.7% vs. 21/35, 60.0%; p < 0.05). When the age threshold exceeded 62.5 years and the serum prostate specific antigen (PSA) threshold exceeded 9.4 ng/ml, a higher uptake of PSMA was more likely to occur in the lesions of low- and intermediate-risk PCa. Conclusion The diagnostic performance of 68Ga-PSMA PET/CT was superior to that of mpMRI in the high-risk PCa cohort, which was consistent with prior studies. Furthermore, in the initial diagnosis of low- and intermediate-risk PCa, we found that mpMRI showed a higher diagnostic accuracy than 68Ga-PSMA PET/CT did. Low- and intermediate-risk PCa patients with a PSA ≥ 9.4 ng/ml and age ≥ 62.5 years were more likely to have a positive 68Ga-PSMA PET/CT result.

Very Low Prostate PET/CT PSMA Uptake May Be Misleading in Staging Radical Prostatectomy Candidates

“…A wide range of cutoffs was proposed to detect significant prostate cancer, ranging from the SUVmax 3.15 to up to the SUVmax 9.1 [ 9 , 10 , 11 , 12 ]. In the current work, we applied the SUVmax of 6.6 cutoff, as previously described by Uprimny et al [ 8 ].…”

The use of 68Ga‐PSMA PET/CT to stratify patients with PI‐RADS 3 lesions according to clinically significant prostate cancer risk

“…That is why 68 Ga-PSMA PET/CT is more recommended in cases of clinically suspected intermediate-or high-risk PCa, 17 even though mpMRI is recommended before the first prostate biopsy to increase accuracy in the diagnosis of PCa.…”

“…Subsequent scans were performed 40 ± 10 min later using a PET/CT scanner (690 Elite; General Electric Healthcare). The detailed imaging protocols (parameters, manufacturer, antibody preparation, and operative approach) have been described in our prior studies 17,18 …”

“…The detailed imaging protocols (parameters, manufacturer, antibody preparation, and operative approach) have been described in our prior studies. 17,18 All images were reviewed by two nuclear medicine physicians with over 5 years of prostate PET/CT experience. Images with inconsistent results were decided by joint assessment and consensus.…”

Occupational radiation exposure assessment during the management of [68Ga]Ga-DOTA-TOC

“…The use of gallium-68 ( 68 Ga) has increased over the last few years [ 9 ], especially for the diagnosis of prostate cancer (PCa) with [ 68 Ga]Ga-PSMA [ 10 ], and neuroendocrine tumours (NET) with [ 68 Ga]Ga-DOTA-TOC [ 11 , 12 ]. However, these are still novel radiopharmaceuticals, so there is a paucity of studies addressing occupational dosimetry from exposure to 68 Ga-based peptides [ 13 ].…”