FDG PET/CT Pitfalls in Gynecologic and Genitourinary Oncologic Imaging

Abstract

The role of whole-body positron emission tomography (PET)/computed tomography (CT) with fluorodeoxyglucose ( FDG fluorodeoxyglucose ) is now established in the assessment of many gynecologic and genitourinary malignant tumors. FDG fluorodeoxyglucose PET/CT has been widely adopted for staging assessments in patients with suspected advanced disease, in cases of suspected disease recurrence, and for determining prognosis in a number of malignancies. A number of pitfalls are commonly encountered when reviewing FDG fluorodeoxyglucose PET/CT scans in gynecologic and genitourinary cases; these pitfalls can be classified into those that yield potential false-positive or false-negative results. Potential false positives include physiologic uptake of FDG fluorodeoxyglucose by the endometrium and ovaries in premenopausal patients, physiologic renal excretion of FDG fluorodeoxyglucose into the ureters and the urinary bladder, and increased FDG fluorodeoxyglucose activity in benign conditions such as uterine fibroids, pelvic inflammatory disease, and benign endometriotic cysts. Potential false negatives include low-level FDG fluorodeoxyglucose uptake by necrotic, mucinous, cystic, or low-grade tumors and the masking of serosal and peritoneal disease by adjacent physiologic bowel or bladder activity. In addition, there are inherent technical limitations-such as motion artifact (from respiratory motion and bowel peristalsis) and the limited spatial resolution of PET-that may limit the assessment of small-volume malignant disease. Knowledge of the key imaging features of physiologic and nonphysiologic FDG fluorodeoxyglucose uptake, in addition to understanding the principles of adequate patient preparation and PET scanning protocols, is important for accurate interpretation of gynecologic and genitourinary oncologic FDG fluorodeoxyglucose PET/CT studies. RSNA, 2017.

Pretreatment tumor-related leukocytosis misleads positron emission tomography-computed tomography during lymph node staging in gynecological malignancies

“…It has been generally accepted that 18F-FDG-PET/CT has higher diagnostic performance than CT or MRI in detecting metastatic lymph nodes in gynecological cancer patients 26 . Although it has been reported that 18F-FDG-PET/CT reliably detects lymph node deposits with a volume larger than 80 mm 3 27 , false-positive detection of lymph node involvement has been caused by benign conditions, including systemic inflammation, infectious diseases, or immunizations 28 . In our patients, false- 10 2 10 3 10 4 10 5 10 2 10 3 10 4 10 5 10 2 10 3 10 4 10 5 10 2 10 3 10 4 10 5 10 2 10 3 10 4 10 5 10 2 10 3 10 4 10 5 10 2 10 3 10 4 10 5 10 2 10 3 10 4 10 5 10 2 10 3 10 4 10 5 10 2 10 3 10 4 10 5 10 2 10 3 10 4 10 5 10 2 10 3 10 4 10 5 Fig.…”

Pilot study utilizing Fluorine‐18 fluorodeoxyglucose‐positron emission tomography/computed tomography for glycolytic phenotyping of canine mast cell tumors

“…Studies in human medicine have shown that necrotic masses, in particular metastatic lymph nodes, will have a falsely lowered SUV max secondary to partial volume effects as they have only a thin, metabolically active periphery. 18,28,29 Grade of mast cell tumor was significantly associated with mitotic index, Ki-67 expression, and c-Kit mutation status of exons, all of which have been shown to be related to prognosis. 26 As a secondary aim, evaluation of the utility of F18 FDG PET-CT for clinical staging in comparison to traditional methods was also evaluated.…”

“…However, in this case it may also be due in part to the large necrotic component that was noncontrast enhancing and relatively non‐avid. Studies in human medicine have shown that necrotic masses, in particular metastatic lymph nodes, will have a falsely lowered SUV max secondary to partial volume effects as they have only a thin, metabolically active periphery …”

Clinical Value of 18 F-fluorodeoxyglucose Positron Emission Tomography/Computed Tomography in Response Evaluation after Primary Treatment of Advanced Epithelial Ovarian Cancer

“…There are two possible explanations. First, an over interpretation of the inflammatory or physiological 18 F-FDG accumulation as cancerous lesions is possible [23].…”

“…Accumulation of 18 F-FDG near the bowel loops in etPET/CT is especially challenging [23]. Physiological bowel uptake is a common finding, which can complicate the interpretation of the metabolic response of the preoperatively detected tumour in the same anatomic area (Figure 2a).…”