FDG PET-CT of gynecologic cancers: pearls and pitfalls.

FDG PET-CT plays an important role in treatment planning and in prognosis assessment of gynecologic cancer patients. Detection of hypermetabolic tissue with FDG PET, when combined with the high spatial resolution of CT, results in improved cancer detection and localization not afforded by either modality independently. This article is a primer for a radiologist performing PET-CT on gynecologic cancer patients and includes the imaging protocol, normal pattern of FDG distribution in the female pelvis and the lymph node drainage pathways from the gynecologic organs. Clinically relevant imaging findings that should be included in the report are discussed. Case examples illustrate how potential errors in exam interpretation can be avoided by concurrently performing a high-quality diagnostic CT with the FDG PET scan and by analyzing both the stand-alone and the fusion images.

Imaging of the adnexal mass.

Imaging plays a central role in the diagnosis of adnexal masses, from the initial detection to characterization. Although ultrasound is often the first-line imaging modality in patients with adnexal masses, magnetic resonance imaging, computed tomography, and sometimes positron emission tomography-computed tomography are used for further evaluation. This chapter discusses the role of different imaging modalities in the evaluation of adnexal lesions as well as provides a summary of key imaging findings of common adnexal lesions.

Magnetic resonance cholangiopancreatography of benign disorders of the biliary system.

Magnetic resonance cholangiopancreatography (MRCP) is an elegant MR technique for noninvasively delineating the biliary system. Technologic advances in MRCP acquisition and processing and the routine availability of three-dimensional sequences have facilitated detailed assessment of biliary anatomy and pathologic or congenital processes; therefore, invasive endoscopic retrograde cholangiopancreatography is rarely needed for establishing a diagnosis. MRCP can be combined with contrast-enhanced MR imaging to enable concurrent evaluation of organs such as the liver and pancreas in addition to functional biliary imaging. This review focuses on the current use of MRCP to evaluate nonmalignant processes affecting the biliary system.

Prediction of metastatic disease and survival in patients with gastric and gastroesophageal junction tumors: the incremental value of PET-CT over PET and the clinical role of primary tumor volume measurements.

RATIONALE AND OBJECTIVES: To investigate the accuracy of M staging (staging of metastatic disease) in esophageal carcinoma based on a visual interpretation and based on tumor volume measurements on positron emission tomography (PET) computed tomography (CT). MATERIALS AND METHODS: Fifty-nine untreated patients with gastroesophageal junction tumors were enrolled, including 36 subcardial gastric tumors (type III according to Siewert classification) and 23 adenocarcinomas of the cardia (AEG, type II Siewert). Patients were grouped in metastasis free (M0 stage, n = 34) and metastatic stages (M1 stage, n = 25). Tumor volume and mean and maximum standardized uptake value were measured on PET-CT. The accuracy of these quantitative tumor volume parameters in distinguishing metastasis-free tumors (M0 stage) from metastatic stages (M1 stage) was compared to the accuracy of a visual analysis with fused PET-CT. Furthermore, accuracy of PET-CT was compared to PET reviewed side by side with CT in a lesion-based analysis of 84 distant metastatic sites. RESULTS: In the visual interpretation, PET-CT (accuracy 88%, 74/84) was more accurate than PET (accuracy 78%, 66/84; P = .008) in characterizing the 84 potential metastatic sites in the 59 patients. Among the tumor parameters, the PET-CT tumor volume was the most accurate predictor of M1 stage and overall survival. With a threshold of 39 mL, PET-CT volume was able to predict M1 stage disease with a sensitivity of 96% and a specificity of 85%. The accuracy of M-staging was increased further when combining tumor volume measurements with the results from the visual analysis (combined results: sensitivity 96%, specificity 94%). CONCLUSIONS: PET-CT was more accurate than PET (reviewed side by side with CT) in characterizing distant metastatic sites of gastroesophageal junction carcinomas. The highest accuracy for M-staging was obtained when combining the results of the visual analysis with the results from primary tumor volume measurements. Primary tumor volume was shown to be an independent prognostic factor.

Imaging of sarcoidosis: self-assessment module.

The educational objectives for this self-assessment module are for the participant to exercise, self-assess, and improve his or her understanding of the imaging features of sarcoidosis and the role of imaging in the clinical management of patients with sarcoidosis.

Imaging features of sarcoidosis on MDCT, FDG PET, and PET/CT.

OBJECTIVE: The objectives of this article are to discuss the epidemiology and natural history of sarcoidosis; to review the classic imaging features of sarcoidosis on radiography, CT, and 67Ga nuclear medicine scans; and to present clinical examples of sarcoidosis as seen on PET and PET/CT in the chest, abdomen and pelvis, and bones. CONCLUSION: The imaging features of sarcoidosis are diverse and can be seen on a variety of imaging techniques. It is important for radiologists and nuclear medicine physicians to recognize the common imaging features and patterns of sarcoidosis in order to raise the possibility in the appropriate clinical setting.

Bowel hot spots at PET-CT.

Positron emission tomography (PET) with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) has been shown to be sensitive in the detection of many bowel malignancies, but its specificity is lower because of various physiologic and pathologic patterns of bowel FDG uptake. PET-computed tomography (CT) can be useful in localizing and characterizing foci of increased FDG uptake within the bowel. As the use of PET-CT in the staging and monitoring of oncologic disease continues to expand, familiarity with these patterns of bowel FDG uptake is essential and can help determine the need for and the relative urgency of further testing. Although a variety of imaging protocols are used for PET-CT, the use of negative oral contrast agent allows improved bowel distention while eliminating potential artifacts caused by high-density oral contrast agents. In addition, correlation with the CT portion of the combined PET-CT examination can sometimes help identify the cause of focal or segmental bowel uptake. The radiologist should be aware of potential pitfalls in the evaluation of FDG-avid foci within the abdomen, including bowel motility and low-attenuation lesions mimicking bowel. Nevertheless, even though the precise role of combined PET-CT for bowel assessment has yet to be determined, the application of sound basic principles of image interpretation will help ensure the accurate interpretation of bowel findings seen with this combined modality.