FDG PET-CT of Genitourinary and Gynecologic Tumors: Overcoming the Challenges of Evaluating the Abdomen and Pelvis  Leslie K. Lee, MD, Aoife Kilcoyne, MD, Shlomit Goldberg-Stein, MD, David Z. Chow, MD, Susanna I. Lee, MD, PhD  Seminars in Roentgenology  Volume 51, Issue 1, Pages 2-11 (January 2016) DOI: 10.1053/j.ro.2015.12.007 Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 1 Physiological uptake in the premenopausal female pelvis. Contrast-enhanced CT (A and C) and axial PET (B and D) images of a premenopausal woman with hypermetabolic follicular phase endometrium (arrow) (A and B) and another with hypermetabolic corpus luteum (arrow) in the right ovary (C and D). Seminars in Roentgenology 2016 51, 2-11DOI: (10.1053/j.ro.2015.12.007) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 2 Elevated physiological tracer uptake. Coronal MIP images from a whole-body PET examination. (A) A 48-year-old woman with extensive cervical, supraclavicular, and paraspinal brown fat uptake, the latter extending to the upper abdomen (arrow). (B) A 47-year-old man with diffuse skeletal muscle uptake of postprandial state. (C) A 55-year-old woman with diffuse bilateral psoas muscle uptake from prior exercise. (D) A 74-year-old woman with diffuse colonic uptake from metformin. MIP, maximum intensity projection. Seminars in Roentgenology 2016 51, 2-11DOI: (10.1053/j.ro.2015.12.007) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 3 False-positive findings due to inflammation. Contrast-enhanced CT (A) and axial PET (B) images of a 51-year-old woman with uterine endometrioid adenocarcinoma demonstrate an intensely hypermetabolic uterine mass (arrowhead) and an enlarged FDG-avid right obdurator lymph node (arrow). At surgery, the lymph node was found to be negative for tumor and reactive secondary to superimposed endometrial infection. Seminars in Roentgenology 2016 51, 2-11DOI: (10.1053/j.ro.2015.12.007) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 4 False-positive findings due to benign neoplasm. Axial contrast-enhanced CT (A) and PET (A) images demonstrate of bilateral adrenal nodules with intense tracer uptake (arrows) suggestive of metastases in this patient with lung cancer. Needle biopsy revealed adrenal adenomas confirmed on follow-up imaging. Seminars in Roentgenology 2016 51, 2-11DOI: (10.1053/j.ro.2015.12.007) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 5 False-positive findings due to benign neoplasm. Coronal MIP from whole-body PET of a 70-year-old man shows a known mesenteric lymphomatous mass (asterisk) and 3 sites of intense colonic uptake (arrowheads) localizing to cecum and distal sigmoid colon. On colonoscopy, tubular adenoma was removed from the cecum and from the sigmoid colon, whereas a hyperplastic polyp was removed from the sigmoid colon. MIP, maximum intensity projection. Seminars in Roentgenology 2016 51, 2-11DOI: (10.1053/j.ro.2015.12.007) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 6 False-positive findings due to anatomic variation of normal tracer. Axial PET (A) image of a 74-year-old man with lymphoma demonstrates an intensely avid right pelvic sidewall lesion (asterisk) resembling an enlarged lymph node which on the concurrent CT (B) corresponds to a bladder diverticulum. Seminars in Roentgenology 2016 51, 2-11DOI: (10.1053/j.ro.2015.12.007) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 7 False-positive findings due to mislocalization of normal tracer. PET image (A) of a 64-year-old woman with uterine clear cell carcinoma demonstrates focal uptake in the right pelvis thought to represent lymphadenopathy. Correlation to a CT image (B) obtained in a separate gantry demonstrates an 8mm lymph node (arrowhead) adjacent to the right ureter (arrow). Surgical lymph node resection demonstrated no tumor. Thus, the focus of tracer likely represented urine in the right ureter. Seminars in Roentgenology 2016 51, 2-11DOI: (10.1053/j.ro.2015.12.007) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 8 Mislocalized tracer due to respiratory motion. Coronal MIP PET image (A) of an 81-year-old man demonstrates an intense focus of uptake (arrow) near the right diaphragm, which could be localized to either liver or lung. Concurrent CT (B) demonstrates no right lung base nodule. Axial T2-weighted image from a subsequent MRI (C) reveals a hyperintense liver metastasis (arrow). MIP, maximum intensity projection; MRI, magnetic resonance imaging. Seminars in Roentgenology 2016 51, 2-11DOI: (10.1053/j.ro.2015.12.007) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 9 Mislocalized tracer on attenuation correction CT. Axial PET image (A) of a 92-year-old man shows an intense focus of uptake (arrowhead) in the right lower quadrant, which on the concurrent low-dose attenuation correction CT (B) appears to localize to bowel lumen. Subsequent diagnostic CT with intravenous contrast (C) demonstrates a serosal peritoneal metastasis (arrowhead) on this same bowel loop. Seminars in Roentgenology 2016 51, 2-11DOI: (10.1053/j.ro.2015.12.007) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 10 False-negative findings due to small lesion size. Axial PET (A) of a 76-year-old man shows diffuse low-level uptake (arrow) in the right hemiabdomen, which on the concurrent low-dose attenuation correction CT (B) appears nonspecific. Diagnostic CT with intravenous contrast (C) shows enhancing <5mm peritoneal nodules of carcinomatosis (arrow). Seminars in Roentgenology 2016 51, 2-11DOI: (10.1053/j.ro.2015.12.007) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 11 False-negative non–FDG-avid malignancy. Axial PET image (A) of a 58-year-old man demonstrates a left renal lesion that is predominantly photopenic with low-level uptake in the periphery (arrow). CT with intravenous contrast (B) demonstrates a 4cm heterogeneously enhancing mass with a thick irregular rind consistent with renal cell carcinoma. Seminars in Roentgenology 2016 51, 2-11DOI: (10.1053/j.ro.2015.12.007) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 12 False-negative findings due to background tracer. CT with intravenous contrast (A) of an 82-year-old woman with known lung cancer shows an enhancing right bladder mass (arrow) consistent with transitional cell carcinoma which, on the concurrent axial PET image (B), is obscured by urinary tracer. Seminars in Roentgenology 2016 51, 2-11DOI: (10.1053/j.ro.2015.12.007) Copyright © 2016 Elsevier Inc. Terms and Conditions

Figure 13 False-negative findings due to background tracer. Contrast-enhanced CT (A) of a 39-year-old woman with history of cervical squamous cell carcinoma demonstrates an enhancing mass posterior to the bladder (arrow) subsequently confirmed as tumor recurrence. On the corresponding axial PET image (B), the recurrence is obscured by adjacent bladder signal but on an obliquely reformatted PET image (C), it is perceived as FDG avid (arrow). Oblique reformatting of image data helps to resolve abnormal signal from adjacent intense urine activity in the bladder. Seminars in Roentgenology 2016 51, 2-11DOI: (10.1053/j.ro.2015.12.007) Copyright © 2016 Elsevier Inc. Terms and Conditions