Whole-Body ¹⁸F FDG-PET/CT: The Need for a Standardized Field of View—A Referring-Physician Aid

Abstract

PET/CT fusion of anatomic and functional imaging modalities is in evolution, with rapid clinical dissemination. The imaged field of view (FOV) selected for whole-body PET/CT protocols is not standardized and varies by institution. Misuse of the term whole body, as well as the pressure to increase the number of daily studies by reducing scanning time, contributes to the lack of standardization. The purpose of this study was to evaluate variations in the FOV and arm positioning selected for whole-body PET/CT protocols at private, as well as academic, PET centers. Methods: Two hundred consecutive whole-body ¹⁸F-FDG PET/CT studies were retrospectively reviewed for FOV: 50 studies from a private stationary site, 50 studies from 2 separate private mobile sites (25 consecutive studies from each), and 100 studies from a stationary university site: 50 before and 50 after implementation of a true whole-body protocol covering the top of the head through the bottom of the feet. Data were categorized into 5 different anatomic scan lengths: base of skull to upper thigh, base of skull to mid thigh, top of head to upper thigh, top of head to mid thigh, and true whole-body. Studies were further categorized into 2 patient arm positions: up and down. Results: The private stationary and mobile sites had only 2 categories of anatomic scan lengths identified: base of skull to mid thigh, and top of head to upper thigh. At the university site, before implementation of a true whole-body protocol, the 5 different anatomic scan lengths were identified; after implementation, only the true whole-body scan length was identified. Patients’ arms in the private stationary sites were down 100% of the time. At the private mobile sites, patients’ arms were up 72% of the time and down 28% of the time. At the university site, patients’ arms were up 54% of the time and down 46% of the time. The same site, after implementation of a true whole-body protocol, had patients’ arms up 58% of the time and down 42% of the time. Overall, patients’ arms were up 46% of the time and down 54% of the time. Conclusion: The continued use of the term whole body is misleading because frequently it may not include the brain, skull, or significant portions of the upper and lower extremities. PET/CT anatomic scan length varied not only from one site to the next but also within individual sites. The Centers for Medicare and Medicaid Services have different current procedural terminology codes distinguishing between base of skull to upper thigh and true whole-body covering the top of the skull to the bottom of the feet, thus underscoring the need to standardize the terminology used in describing PET/CT scan length.