Journal of nuclear medicine : official publication, Society of Nuclear Medicine
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Early detection of recurrence is clinically important and can improve the prognosis and survival of patients with cancer. CT, considered the primary method of investigation because of its low cost and widespread availability, provides high-resolution anatomic details but may underestimate the actual tumor burden by overlooking small tumor clusters in areas of distorted anatomy after treatment. 18F-FDG PET is an effective whole-body imaging technique that detects metabolic changes preceding structural findings. ⋯ PET/CT provides fused images that demonstrate the complementary roles of functional and anatomic assessments in the diagnosis of cancer recurrence through the precise localization of suspected 18F-FDG foci and their characterization as malignant or benign. In addition to the accurate diagnosis and definition of the whole extent of recurrent cancer, PET/CT has an impact on patient management because it can assist in defining potential candidates for surgery for cure, planning the appropriate surgical or radiotherapy approach, and referring patients with unresectable disease to other therapeutic options.
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Imaging with 18F-FDG PET is increasingly accepted as a valuable tool for lymphoma management. A recent shift in the use of PET and PET/CT in medical practice has become evident. We selected aggressive lymphomas as a platform for the discussion of these imaging modalities in oncology patients and the resulting management questions. ⋯ PET/CT improves the accuracy of staging and response assessment over that of CT alone. A negative midtreatment PET result does not indicate the absence of a viable tumor or that therapy can be abbreviated or reduced in intensity. Similarly, a positive PET result does not necessarily indicate a viable tumor or that extending or intensifying treatment will benefit the patient. In assessing response, it is possible that prognosis rests not only on whether the PET result is positive or negative but also on the intensity of the signal. Although the prognostic value of PET for lymphoma is now clear, how to tailor therapy accordingly is a separate matter that requires further investigation.
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PET with the glucose analog 18F-FDG is increasingly being used to monitor the effectiveness of therapy in patients with malignant lymphomas and a variety of solid tumors. The use of integrated PET/CT instead of stand-alone PET for treatment monitoring poses some methodologic challenges for the quantitative analysis of PET scans but also provides the opportunity to integrate morphologic information and functional information. ⋯ This review addresses how CT-based attenuation correction may affect the quantitative analysis of 18F-FDG PET scans and summarizes the results of recent studies with PET/CT for treatment monitoring for lung cancer and gastrointestinal stromal tumors. The review concludes with an outlook on how PET/CT could make a difference in drug development and clinical management for patients.
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Screening for cancer remains a very emotional and hotly debated issue in contemporary medical practice. An analysis of published data reveals a multitude of opinions based on a limited amount of reliable data. Even for breast cancer screening, which is now widely practiced in the United States and many European countries, there is continuing controversy regarding the appropriate age limits for screening mammography and, in fact, concerning the value of mammography itself. ⋯ Because of prohibitive costs and the required length of follow-up, it is unlikely that such a trial will ever be conducted. Rather than spending time and resources on screening studies, medical practitioners should continue using whole-body PET/CT for diagnosing, staging, and restaging cancer and for monitoring treatment effects. Researchers should also investigate the utility of whole-body PET/CT for the surveillance of selected groups of patients who have cancer, who have completed curative treatment, but who remain at high risk for recurrent disease.