Evaluation of Practical Interpretation Hurdles in 68Ga-PSMA PET/CT in 55 Patients: Physiological Tracer Distribution and Incidental Tracer Uptake. (July 2017)

• Record Type: Journal Article
• Authors: Kirchner, Julian; Schaarschmidt, Benedikt Michael; Sawicki, Lino Morris; Heusch, Philipp; Hautzel, Hubertus; Ermert, Johannes; Rabenalt, Robert; Antoch, Gerald; Buchbender, Christian
• Is Part Of: Clinical nuclear medicine. Volume 42:Number 7(2017)
• Publication Date: 2017-07
• Subjects: 68Ga-PSMA PET/CT -- physiological tracer distribution -- incidental 68Ga-PSMA uptake; Nuclear medicine -- Periodicals; Radioisotope scanning -- Periodicals; Nuclear Medicine -- Periodicals; 616.07575
• DOI: 10.1097/RLU.0000000000001672
• Languages: English
• ISSNs: 0363-9762

Abstract

Abstract : Purpose: To investigate the physiologic 68 Ga-PSMA distribution and evaluate focal or diffuse radiotracer uptake in nonprostate cancer malignancies and in incidental findings. Methods: 68 Ga-PSMA PET/CT scans in 55 men performed for prostate cancer (49) or renal cell carcinoma (6) staging were analyzed retrospectively. Two radiologists evaluated the datasets in 2 reading sessions. First, physiological 68 Ga-PSMA uptake was evaluated. Second, scans were analyzed for incidental uptake. SUVmax and SUVmean were recorded. Other imaging modalities, histopathology, or clinical follow-up served as standard of reference. Results: Homogenous 68 Ga-PSMA uptake of the lacrimal glands (SUVmax, 15.7 ± 7.2), parotid glands (SUVmax, 24.4 ± 8.1), submandibular glands (SUVmax, 26.7 ± 7.1), vocal cords (SUVmax, 8.4 ± 3), Waldeyer ring (SUVmax, 10.4 ± 4.3), liver (SUVmax, 8.2 ± 2.5), spleen (SUVmax, 10.9 ± 3.9), kidneys (SUVmax, 66.4 ± 25.4), and pars descendens duodeni (SUVmax, 17.6 ± 8.9) was observed in all patients. In 65% and 36%, respectively, homogenous 68 Ga-PSMA uptake of the colon descendens (SUVmax, 10.6 ± 9.2) and the rectum (SUVmax, 3.7 ± 1.1) was found. Approximately 22% exhibited a 68 Ga-PSMA uptake of the thyroid (SUVmax, 4.5 ± 1.2), and 21% exhibited a 68 Ga-PSMA uptake of the knee's synovia (SUVmax, 2.9 ± 0.2). Furthermore, 68 Ga-PSMA uptake was found in 1 patient because of fibrous dysplasia of the right os ilium (SUVmax, 7.7). Conclusions: Physiologic distribution of 68 Ga-PSMA comprises uptake in lacrimal and salivary glands, vocal cords, Waldeyer ring, liver, spleen, and kidneys as well as various parts of the intestine. Moreover, nonspecific tracer uptake is regularly found in the thyroid and the synovia of the knee. Incidental 68 Ga-PSMA uptake can occasionally reveal nonprostate cancer–associated remodeling processes, such as fibrous dysplasia.