Hansjoerg Rempp, Presenter: Nothing to Disclose

Johannes Schwenck, Abstract Co-Author: Nothing to Disclose

Gerald Reischl MD, PhD, Abstract Co-Author: Nothing to Disclose

Konstantin Nikolaou MD, Abstract Co-Author: Speakers Bureau, Siemens AG Speakers Bureau, Bracco Group Speakers Bureau, Bayer AG

Christian la Fougere, Abstract Co-Author: Nothing to Disclose

Christina Pfannenberg MD, Abstract Co-Author: Nothing to Disclose

The 68Ga-labelled PSMA (prostate specific membrane antigen) ligand is a highly promising tracer for imaging of recurrent prostate cancer (PC). The aim of the study was to compare this novel tracer with the standard 11C-Choline based PET/CT.

42 patients with suspected PC relapse underwent a PET/CT 5 min p.i. of 615±26 MBq 11C-Choline and 60 min p.i. of 157±16 MBq 68Ga-HBED-CC-PSMA. The examinations were performed on the same day. 39 patients had a biochemical relapse after prostatectomy and/or radiotherapy (mean PSA 8.3 ng/ml, range 0.3-64 ng/ml, median 3.3 ng/ml), 3 patients had a primary staging. Suspicious lesions were evaluated visually and semiquantitatively (mean SUV, standard uptake value and T/B, tumor to blood ratio).

In 36/42 patients, at least one lesion suspicious for cancer could be detected using 68Ga-PSMA (detection rate 85.7%), while at least one lesion could be found by 11C-Choline in 34/42 patients (detection rate 81.0%). In five patients no lesion was found in both methods. Twelve patients had local recurrences, whereof 11/12 relapses were detected by both methods. One local relapse was not detected by 68Ga-PSMA. In 1/3 patients with primary staging the tumor could not be detected by either of the tracers. In 28 patients suspicious lymph nodes (LN) were detected. 89% of these patients had at least one PSMA-positive LN, 89% of them had at least one Choline-positive LN. Among all 98 suspicious LN, 86 were PSMA-positive and 80 were Choline-positive. 18 LN were PSMA-positive only, 12 were Choline-positive only. Mean size of the LN which could only be detected by PSMA was 8±3 mm. SUV mean and T/B ratio of the LN was clearly higher using 68Ga-PSMA (15.3±14) than using 11C-Choline (4.4±2). Bone metastases were found in 14 patients, the number of detected lesions as well as tracer uptake was clearly higher using 68Ga-PSMA (SUV mean 11.4±8.4 vs 6±3.2). In one patient bone metastases were only dertected with 68Ga-PSMA PET. In only 8/14 patients, bone metastases could be detected in CT.  

68Ga-PSMA-PET/CT is able to detect recurrent PC with a higher detection rate compared to the standard 11C-Choline PET/CT and has an improved T/B ratio. However, 68Ga-PSMA was not able to detect all primary and metastatic sites.

68Ga-PSMA is a new tracer for prostate cancer, promising particularly for detection of recurrence in patients with low PSA.

Rempp, H, Schwenck, J, Reischl, G, Nikolaou, K, la Fougere, C, Pfannenberg, C, Comparison of 68Ga-labelled PSMA- and 11C-Choline PET/CT for the Detection of Recurrent Prostate Cancer.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14008552.html