Matched-Pair Comparison of ⁶⁸Ga-PSMA-11 PET/CT and ¹⁸F-PSMA-1007 PET/CT: Frequency of Pitfalls and Detection Efficacy in Biochemical Recurrence After Radical Prostatectomy

Abstract

18 F-labeled prostate-specific membrane antigen (PSMA)-ligand PET has several principal advantages over 68 Ga-PSMA-11. The purpose of this retrospective study was to evaluate the frequency of non-tumor-related uptake and the detection efficacy comparing 68 Ga-PSMA-11 PET/CT and 18 F-PSMA-1007 PET/CT in recurrent prostate cancer (PC) patients. Methods: The study included 102 patients with biochemically recurrent PC after radical prostatectomy undergoing 18 F-PSMA-1007 PET/CT imaging. On the basis of various clinical variables, patients with corresponding 68 Ga-PSMA-11 PET/CT scans were matched. All PET/CT scans (n 5 204) were reviewed by 1 nuclear medicine physician. First, all PET-positive lesions were noted. Then, lesions suspected of being recurrent PC were differentiated from lesions attributed to a benign origin on the basis of known pitfalls and information from CT. For each region, the SUV max of the lesion with the highest PSMA-ligand uptake was noted. Detection rates were determined, and SUV max was compared separately for 68 Ga-PSMA-11 and 18 F-PSMA-1007. Results: In total, 18 F-PSMA-1007 PET and 68 Ga-PSMA-11 PET revealed 369 and 178 PSMA-ligand-positive lesions, respectively. 18 F-PSMA-1007 PET revealed approximately 5 times more lesions attributed to a benign origin than did 68 Ga-PSMA-11 PET (245 vs. 52 lesions, respectively). The benign lesions most frequently observed were ganglia, unspecific lymph node, and bone lesions, at a rate of 43%, 31%, and 24% for 18 F-PSMA-1007 PET and 29%, 42%, and 27% for 68 Ga-PSMA-11 PET, respectively. The SUV max of lesions attributed to a benign origin was significantly higher (P , 0.0001) for 18 F-PSMA-1007 PET. Further, a similar number of lesions was attributed to recurrent PC (124/369 for 18 F-PSMA-1007 PET and 126/178 for 68 Ga-PSMA-11 PET). Conclusion: The number of lesions with increased PSMA-ligand uptake attributed to a benign origin is considerably higher for 18 F-PSMA-1007 PET than for 68 Ga-PSMA-11 PET. This finding indicates the need for sophisticated reader training emphasizing known pitfalls and reporting within the clinical context.

Pre-test 68Ga-PSMA-ligand PET/CT positivity in early biochemical recurrent prostate cancer after radical prostatectomy—validation of a prediction model

“…Recently, a higher number of lesions with increased PSMA-ligand uptake attributed to benign origin were observed in 18 F-labelled PSMA-ligand PET in comparison to 68 Ga-PSMA-11 [26]. However, we do not think that this influences the correct establishment of a prediction nomogram as after adequate reader training, physicians should be well equipped to distinguish likely malignant lesions from those that are most probably benign.…”

Head-to-Head Comparison of 68Ga-PSMA-11 with 18F-PSMA-1007 PET/CT in Staging Prostate Cancer Using Histopathology and Immunohistochemical Analysis as a Reference Standard

“…For 68 Ga-PSMA-11, the acquisition was performed between 45 and 80 min after injection, whereas 18 F-PSMA-1007 PET/CT was performed 60 min after injection. These uptake periods were derived from the literature (24,34,35). Theoretically, a longer uptake may lead to an improved tumor-to-background ratio (34,35) and result in bias in favor of the tracer for which a longer uptake was applied.…”

“…Imaging was done from the tip of the skull to the mid thigh. 68 Ga-PSMA-11 was injected 45-80 min before acquisition started (24), and 18 F-PSMA-1007 was injected as a bolus 60 min before acquisition.…”

Results from extended lymphadenectomies with [111In]PSMA-617 for intraoperative detection of PSMA-PET/CT-positive nodal metastatic prostate cancer

“…The most widely studied is 68 Ga labelled to the small molecular inhibitor PSMA-11 via the HBED chelator ([ 68 Ga]PSMA-11, also known as [ 68 Ga]PSMA-HBED-CC) [13]. A recent meta-analysis published by Perera et al showed on a per lymph node analysis a high sensitivity of 75% and a 99% specificity [14] for [ 68 Ga]PSMA-11 PET/ CT. Because of several advantages of the positron emitter 18 F, 18 F-labelled PSMA ligands ([ 18 F]PSMA-1007, [ 18 F]DCFPYL) were used more and more for imaging instead of 68 Ga-labelled PSMA ligands [15,16].…”