Prospective intra-individual blinded comparison of [18F]PSMA-1007 and [68Ga]Ga-PSMA-11 PET/CT imaging in patients with confirmed prostate cancer

Abstract

Introduction[18F]PSMA-1007 has potential advantages over [68Ga]Ga-PSMA-11, although limited prospective data evaluating diagnostic performance exist. The aims of this study are to describe the concordance of [18FPSMA-1007 and [68Ga]Ga-PSMA-11 for TNM with American Joint Committee on Cancer (AJCC) prognostic stage, and assess differences in tracer uptake.MethodsFifty men (mean age 71.8) were imaged with [68Ga]Ga-PSMA-11 and [18F]PSMA-1007 < 4 weeks apart. Images were independently reported according to TNM by two experienced nuclear medicine specialists blinded to the other scan and prior imaging. Discordant results were resolved by a third independent nuclear medicine specialist. Quantitative analysis of lesion uptake and physiologic tissue for each tracer was performed by one experienced reader.ResultsScan indications were initial staging (n = 12), biochemical recurrence (n = 27) and metastatic disease evaluation (n = 11). Most patients had ISUP grade group 3 or higher. Median PSA value was 2.7 ng/ml (IQR 0.7–12.0) and a minority of patients (28%) were currently treated with androgen deprivation therapy. [18F]PSMA-1007 uptake was significantly higher than [68Ga]Ga-PSMA-11 in local recurrence, nodal and distant metastases, and most physiologic sites except for urinary bladder which was significantly lower. [18F]PSMA-1007 upstaged local prostate staging in 5/17 patients, local recurrence in 3/33 patients, regional nodal disease in 3/50 patients and 1 distant metastasis (bladder). [68Ga]Ga-PSMA-11 upstaged regional nodal disease in 1/50 patients and distant metastasis in one patient (right adrenal). Overall AJCC prognostic stage was concordant in 46/50 (92%) patients, with two patients upstaged for both [18F]PSMA-1007 and [68Ga]Ga-PSMA-11. [18F]PSMA-1007 had more equivocal results (one regional node; six equivocal bone lesions, one of which was subsequently confirmed metastatic) than [68Ga]Ga-PSMA-11 (one equivocal local recurrence).ConclusionOverall AJCC prognostic stage was similar (92%) between [18F]PSMA-1007 and [68Ga]Ga-PSMA-11. [18F]PSMA-1007 demonstrates higher uptake within involved nodes and distant metastases, and most physiologic sites except urinary bladder which aided [18F]PSMA-1007 local staging of the prostate primary / local recurrence and regional nodal disease adjacent ureters. However [18F]PSMA-1007 liver uptake obscured a solitary right adrenal metastasis, and more equivocal bone lesions were identified.

Comparison of 18F-PSMA-1007 PET/CT With 68Ga-PSMA-11 PET/CT for Initial Staging in Intermediate- and High-Risk Prostate Cancer

“…Nonrenal mode of excretion of 18 F-PSMA-1007 may help in detecting tumor lesions close to the ureter or urinary bladder, which can be masked by urinary tracer activity of 68 Ga-PSMA-11. This potential advantage may be more clinically relevant in detecting tumor recurrence 26 than in the setting of initial staging, as reported in a study by Pattison et al 18 comparing the 2 radiotracers with heterogeneous scan indications. They found discordant local T staging in 5/17 patients (higher T stage reported on 18 F-PSMA-1007 in all the 5 cases), discordant local recurrence in 3/33 patients (upstaging by 18 F-PSMA in all 3 cases), and discordant nodal staging in 3/14 patients with the major advantage being detection of lesions in proximity to the ureter and in detection of bladder wall invasion.…”

“…A recently published, retrospective, single-center study 17 comparing 68 Ga-PSMA-11 and 18 F-PSMA-1007 in 46 PCa patients found concordant mi(molecular imaging) TNM stages in 80.4% patients. Another prospective study 18 comparing the 2 tracers in 50 PCa patients found overall American Joint Committee on Cancer TNM prognostic stage concordance in 92% patients. A major drawback of both these studies was the heterogeneity in clinical indication for PSMA PET.…”

The Detection Performance of 18F–Prostate-Specific Membrane Antigen-1007 PET/CT in Primary Prostate Cancer

“…14,15,17,18,[29][30][31][32][33][34][35][36] All studies were published between 2016 and 2021 (Table 1), 14,15,17,18,[29][30][31][32][33][34][35][36] and 58% (n = 7) of studies were published in 2021. 14,29,[32][33][34][35]37 Of the 12 studies, 7 were retrospective in design, 14,15,30,31,[33][34][35] with a larger sample size of 96 to 194 in 3 studies 14,15,34 than the other 5 prospective studies. 17,18,29,32,36 Among these 12 studies, 7 studies involved histopathological confirmation.…”

Reducing False-Positives Due to Urinary Stagnation in the Prostatic Urethra on 18F-DCFPyL PSMA PET/CT With MRI

“…Radiotracers used in PSMA PET scans are predominantly eliminated through the urinary system, which creates high background activity in the ureters, bladder, and urethra, complicating interpretation of imaging data. [9][10][11][12][13] In certain cases, intense radiotracer activity in these regions can be misinterpreted as pathological lesions, such as small pelvic lymph nodes or local PCa recurrence, particularly in anatomical structures close to the urinary tract. 9,11 One specific area of concern is the prostatic urethra, where retained urine may further complicate the interpretation of PSMA PET scans.…”

“…[9][10][11][12][13] In certain cases, intense radiotracer activity in these regions can be misinterpreted as pathological lesions, such as small pelvic lymph nodes or local PCa recurrence, particularly in anatomical structures close to the urinary tract. 9,11 One specific area of concern is the prostatic urethra, where retained urine may further complicate the interpretation of PSMA PET scans. Urine can be stagnated within the prostatic urethra for various reasons, including benign prostatic hyperplasia (BPH), prostatitis, postsurgical changes, or anatomical variations that can hinder the free flow of urine.…”