Interesting ImagesWhole-Body 177Lu–Prostate-Specific Membrane Antigen Scan Pattern With Excess Free 177Lu-Chloride in a Metastatic Castration-Resistant Prostate Cancer PatientAskari, Emran MD; Moghadam, Soroush Zarehparvar MD; Divband, Ghasemali MD; Aryana, Kamran MDAuthor Information From the Nuclear Medicine Research Center, Mashhad University of Medical Sciences, Mashhad, Iran. Received for publication March 3, 2020; revision accepted May 11, 2020. Conflicts of interest and sources of funding: none declared. Correspondence to: Kamran Aryana, MD, Nuclear Medicine Research Center, Ghaem Hospital, Mashhad, Iran. E-mail: Aryanak@mums.ac.ir. Clinical Nuclear Medicine: October 2020 - Volume 45 - Issue 10 - p 805-807 doi: 10.1097/RLU.0000000000003167 Buy Metrics Abstract A 56-year-old man with metastatic castration-resistant prostate cancer was referred for radioligand therapy with 177Lu–prostate-specific membrane antigen. In the third cycle, a posttherapy whole-body scan showed unexpected skeletal and joint uptake apart from his known metastatic lesions. This observation raised suspicion for possible impurity (mainly free lutetium) in the applied radiopharmaceutical product. After contacting the radiopharmaceutical company, we were informed that the radiochemical purity of the used batch of 177Lu–prostate-specific membrane antigen had been 95%. This is the first report of excess free lutetium scan pattern and its complications in a patient undergoing radioligand therapy. Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.