Intraindividual comparison of [68 Ga]-Ga-PSMA-11 and [18F]-F-PSMA-1007 in prostate cancer patients: a retrospective single-center analysis

Abstract

Background The analysis aimed to compare the radiotracers [68Ga]-Ga-PSMA-11 and [18F]-F-PSMA-1007 intraindividually in terms of malignant lesions, mi(molecular-imaging)TNM staging and presumable unspecific lesions retrospectively as used in routine clinical practice. Methods A retrospective analysis of 46 prostate cancer patients (median age: 71 years) who underwent consecutive [68Ga]-Ga-PSMA-11- and [18F]-F-PSMA-1007-PET/CT or PET/MRI within a mean of 12 ± 8.0 days was performed. MiTNM staging was performed in both studies by two nuclear medicine physicians who were blinded to the results of the other tracer. After intradisciplinary and interdisciplinary consensus with two radiologists was reached, differences in both malignant and presumable nonspecific tracer accumulation were analyzed. Results Differences in terms of miTNM stages in both studies occurred in nine of the 46 patients (19.6%). The miT stages differed in five patients (10.9%), the miN stages differed in three patients (6.5%), and different miM stages occurred only in one patient who was upstaged in [18F]-F-PSMA-1007 PET. Concordant miTNM stages were obtained in 37 patients (80.4%). There was no significant difference between [18F]-F-PSMA-1007 and [68Ga]-Ga-PSMA-11 in the SUVmax locally (31.5 vs. 32.7; p = 0.658), in lymph node metastases (28.9 vs. 24.9; p = 0.30) or in bone metastases (22.9 vs. 27.6; p = 0.286). In [18F]-F-PSMA-1007 PET, more patients featured presumable unspecific uptake in the lymph nodes (52.2% vs. 28.3%; p: < 0.001), bones (71.7% vs. 23.9%; p < 0.001) and ganglia (71.7% vs. 43.5%; p < 0.001). Probable unspecific, exclusively [18F]-F-PSMA-1007-positive lesions mainly occurred in the ribs (58.7%), axillary lymph nodes (39.1%) and cervical ganglia (28.3%). Conclusion In terms of miTNM staging, both tracers appeared widely exchangeable, as no tracer relevantly outperformed the other. The differences between the two tracers were far more common in presumable unspecific lesions than in malignant spots. A routinely performed two-tracer study could not be shown to be superior. Since it seems at least challenging for most nuclear medicine departments to provide both [18F]-F-PSMA-1007 and [68Ga]-Ga-PSMA-11, it appears reasonable to choose the PSMA radiotracer depending on local availability with attention to the greater occurrence of nonspecific bone findings with [18F]-F-PSMA-1007.

Comparison of [18F]PSMA-1007 with [68Ga]Ga-PSMA-11 PET/CT in Restaging of Prostate Cancer Patients with PSA Relapse

“…At the same time, PSMA imaging began at 18 F. In our study, the rates for multi-metastatic disease in the 68 Ga-PSMA group for patients with PSA values below and above the calculated threshold were 28.6% vs. 68.1% (p = 0.001). Overall, the findings obtained with 18 F-PSMA and 68 Ga-PSMA were similar as also reported by other authors [25,26]. An interesting aspect from our point of view is that a significant subgroup of oligo-metastatic disease could be identified below the threshold of both methods which may be suitable as a selection criterion for targeted therapy.…”

Preclinical comparative study of [18F]AlF-PSMA-11 and [18F]PSMA-1007 in varying PSMA expressing tumors

“…A meta-analysis by Liu et al reported a pooled sensitivity and specificity of 0.923 and 0.442 for PSA > 2 ng/mL and 0.832 and 0.277 for PSA ≤ 2 ng/mL, respectively 18 . These results were confirmed by an intra-individual comparative study by Hoberück et al 19 . The authors reported the exchangeability of both tracers depending on the availability, but highlighted the increased incidence of non-specific bone findings with [ 18 F]PSMA-1007.…”

Risk of metastatic disease using [18F]PSMA-1007 PET/CT for primary prostate cancer staging

“…This is based on strong evidence with multiple studies using both [ 18 F]PSMA-1007 PET/CT and [ 68 Ga]Ga-PSMA-11 PET/CT confirming an excellent diagnostic accuracy and high positive predictive value for the detection of metastatic disease with histopathological validation [ 4 , 13 , 14 , 26 – 29 ]. Additionally, a recent prospective intra-individual comparative study has demonstrated excellent concordance between [ 18 F]PSMA-1007 and [ 68 Ga]Ga-PSMA-11 PET/CT [ 30 , 31 ]. Therefore, we consider [ 18 F]PSMA-1007 PET/CT as an acceptable substitute for histopathological validation based on this extensive literature.…”