Comparison of PET imaging with a (68)Ga-labelled PSMA ligand and (18)F-choline-based PET/CT for the diagnosis of recurrent prostate cancer

• Published in: European journal of nuclear medicine and molecular imaging Vol. 41; no. 1; pp. 11 - 20
• Main Authors: Afshar-Oromieh, Ali, Zechmann, Christian M, Malcher, Anna, Eder, Matthias, Eisenhut, Michael, Linhart, Heinz G, Holland-Letz, Tim, Hadaschik, Boris A, Giesel, Frederik L, Debus, Jürgen, Haberkorn, Uwe
• Format: Journal Article
• Language: English
• Published: Germany 01.01.2014
• Subjects: Aged; Aged, 80 and over; Antigens, Surface - metabolism; Choline - analogs & derivatives; Gallium Radioisotopes; Glutamate Carboxypeptidase II - metabolism; Humans; Ligands; Male; Middle Aged; Multimodal Imaging; Positron-Emission Tomography; Prostatic Neoplasms - diagnostic imaging; Recurrence; Tomography, X-Ray Computed
• ISSN: 1619-7089
• DOI: 10.1007/s00259-013-2525-5

Positron emission tomography (PET) with choline tracers has found widespread use for the diagnosis of prostate cancer (PC). However, choline metabolism is not increased in a considerable number of cases, whereas prostate-specific membrane antigen (PSMA) is overexpressed in most PCs. Therefore, a (68)Ga-labelled PSMA ligand could be superior to choline tracers by obtaining a high contrast. The aim of this study was to compare such a novel tracer with standard choline-based PET/CT. Thirty-seven patients with biochemical relapse of PC [mean prostate-specific antigen (PSA) 11.1 ± 24.1 ng/ml, range 0.01-116] were retrospectively analysed after (18)F-fluoromethylcholine and (68)Ga-PSMA PET/CT within a time window of 30 days. Radiotracer uptake that was visually considered as PC was semi-quantitatively analysed by measuring the maximum standardized uptake values (SUVmax) of the scans acquired 1 h after injection of (68)Ga-PSMA complex solution (median 132 MBq, range 59-263 MBq) and (18)F-fluoromethylcholine (median 237 MBq, range 114-374 MBq), respectively. In addition, tumour to background ratios were calculated. A total of 78 lesions characteristic for PC were detected in 32 patients using (68)Ga-PSMA PET/CT and 56 lesions were detected in 26 patients using choline PET/CT. The higher detection rate in (68)Ga-PSMA PET/CT was statistically significant (p=0.04). In five patients no lesion was found with both methods. All lesions detected by (18)F-fluoromethylcholine PET/CT were also seen by (68)Ga-PSMA PET/CT. In (68)Ga-PSMA PET/CT SUVmax was clearly (>10 %) higher in 62 of 78 lesions (79.1 %) and the tumour to background ratio was clearly (>10 %) higher in 74 of 78 lesions (94.9 %) when compared to (18)F-fluoromethylcholine PET/CT. (68)Ga-PSMA PET/CT can detect lesions characteristic for PC with improved contrast when compared to standard (18)F-fluoromethylcholine PET/CT, especially at low PSA levels.