PET/MR further improves detection of ^sup 68^Ga-PSMA imaging for early biochemical recurrence in prostate cancer

• Published in: The Journal of nuclear medicine (1978) Vol. 58; p. 709
• Main Authors: Burger, Irene, Kranzbuehler, Benedikt, Nagel, Hannes, Huellner, Martin, Stolzmann, Paul, Eberli, Daniel
• Format: Journal Article
• Language: English
• Published: New York Society of Nuclear Medicine 01.05.2017
• Subjects: Biochemistry; Cancer; Computed tomography; Disease control; Lesions; Lymph nodes; Medical diagnosis; Medical imaging; Medical treatment; Metastases; Nuclear medicine; Oncology; Patients; Pelvis; Positron emission; Prostate cancer; Radiation; Radiation therapy; Salvage; Surgery; Tomography; Urine
• ISSN: 0161-5505; 1535-5667

Objectives: Sensitive detection of early biochemical recurrence (EBR) of prostate cancer (PCa) is mandatory to direct curative treatment options (salvage radiation therapy/surgery), if disease is limited to the prostate fossa or the regional lymph nodes. The recently established 68Ga-PSMA-PET/CT has significantly improved the detection rate with up to 55% for patients with a PSA 0.2-0.5 ng/ml. The increased softtissue contrast in the pelvis using PET/MR might further improve the detection rate for EBR with low PSA values. Methods: A board certified radiologist and nuclear medicine physician retrospectively analyzed 56 patients that underwent a 68Ga-PSMA PET/MR for EBR in our institution between April-December 2016. PSA-levels ranged between 0.05 - 30 ng/ml. PSMA-positive lesions were recorded for local recurrences, pelvic and extra pelvic lymph nodes and bone metastasis and detection rate of 68Ga-PSMA PET/MR was calculated on a per patient base for 4 different patient groups according to PSA levels. Results: Overall in 44 of 56 patients (79%) pathological PSMA-positive lesions were detected using 68Ga-PSMA PET/MR. In 9 patients with PSA between 0.05-0.2 ng/ml suspicious lesions were detected in four patients (44%, pelvic (2) and extra pelvic (1) lymph nodes and one bone metastasis). In 9 of 12 (75%) patients with PSA between 0.2-0.5 ng/ml suspicious lesions were detected (local recurrences (3), pelvic lymph nodes (5) one with one extra pelvic node and one bone metastasis).In 12 of 15 (80%) patients with PSA between 0.5-2.0 ng/ml suspicious lesions were detected (local recurrences (3), pelvic lymph nodes (9) in one patient with extra pelvic nodes and four with bone metastasis). In 14 of 16 patients (88%) with PSA > 2.0 ng/ml suspicious lesions were detected (two had only local recurrences (PSA 4.5 and 7.6 ng/ml), 12 patients had lymph node metastasis and three patients additional bone metastasis. Conclusion: This data suggest that 68Ga-PSMA PET/MR might further improve the detection rate of 68Ga-PSMA imaging compared to PET/CT, probably due to an improved allocation of PSMA-Tracer activity with soft-tissue versus urine in the pelvic area. Furthermore it shows that even at very low PSA levels between 0.05-0.5 ng/ml extra pelvic disease can be localized in 19% of the cases and just local recurrence is seen only in 14% while 33% have pelvic lymph node metastasis.