Dual-Tracer PET/CT Differentiates 2 Types of Primary Cancers and Metastases in a Patient With Crossed Fused Renal EctopiaHo, Chi-lai, MD*; Chen, Sirong, PhD*†; Leung, Yim Lung, MBBS*; Cheng, Kam Chau, MBBS*; Wong, Yuet Hung, MBBS*Clinical Nuclear Medicine: February 2019 - Volume 44 - Issue 2 - p 157–158 doi: 10.1097/RLU.0000000000002390 Interesting Images Abstract Author InformationAuthors Article MetricsMetrics A patient was found incidentally on dual-tracer (11C-acetate [ACT] and 18F-FDG [FDG]) PET/CT for having crossed fused renal ectopia and 2 types of malignant tumors, colonic carcinoma and renal cell carcinoma (RCC), each having its own characteristic tracer avidity. Multiple liver metastases were also mutually exclusive, with a purely ACT-avid group of metastatic lesions from RCC and another FDG-avid group from colonic carcinoma. Bone and lung metastases, however, could not be readily distinguishable in terms of primary origins. Crossed fused renal ectopia is a rare anomaly, even rarer to have RCC coexisting with a second primary malignancy. From the *Department of Nuclear Medicine & PET and †Medical Physics & Research Department, Hong Kong Sanatorium & Hospital, Hong Kong, China. Received for publication August 31, 2018; revision accepted October 11, 2018. Conflicts of interest and sources of funding: none declared. Correspondence to: Chi-lai Ho, MD, Department of Nuclear Medicine & PET; Hong Kong Sanatorium & Hospital, 2 Village Road, Happy Valley, Hong Kong, China. E-mail: firstname.lastname@example.org. Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.