512 chapter 13 Here, I would like to emphasize the importance of initiatives such as EARL, as it enables high-quality, multicentre trials with reproducible PET data, such as the EfFECTS trial, which would never have been feasible in a single centre setting for a relatively rare condition like Bethesda III/IV thyroid nodules. Fortunately, EARL-accreditation is much more common nowadays than it was in 2015 (https://earl. eanm.org/centres-of-excellence-network/). Moreover, some limitations can be overcome by pragmatic solutions: for two of our participating hospitals without EARL accreditation, included patients underwent their [18F]FDG-PET/CT at another, EARL-accredited study site, thanks to the hospitality of the local principle investigator there. Such solutions may be considered to sustain the high quality of the study data when a high number of patient inclusions is desired but when some of the anticipated study sites may not be able to adhere to the EANM guidelines, provided that other study sites have the extra [18F]FDG-PET/CT capacity, that good multicentric collaboration agreements are made, and that the travel distance and additional burden for participating patients is taken into account. Partial body scanning Second, we performed a partial body [18F]FDG-PET/CT that only included the thyroid region, i.e., approximately from the external ear canal to the aortic arch. By scanning partial-body, the number of required bed positions and therefore total scanning time can be limited, which saves costs, radiation exposure, and/or may prevent undesirable, clinically irrelevant incidental findings that may lead to additional diagnostic tests and unbeneficial treatment delays [501]. By subsequently increasing the scanner time per bed position and lowering the dose of [18F]FDG in accordance with the EANM guidelines, the total radiation dose of a partial body [18F]FDG-PET/CT can likely be limited to less than 1 mSv [468]. For the latest generation of [18F]FDG-PET/CT scanners, the radiation dose can even be minimized without this being at the expense of the scanner time. Partial body PET scanning was long considered highly unusual as the [18F]FDG activity already circulated throughout the body – so why not image it – especially back when stand-alone PET scanning was the standard. Moreover, whole body scanning is considered relevant for many oncological purposes, one of the major drivers for marketing large-field-of-view PET/CT scanners that are currently on the market. Yet, for the preoperative diagnosis of indeterminate thyroid nodules, where no relevant findings are expected outside the neck region, partial body scanning is a perfect and suitable solution to limit valuable resources and improve its clinical utility. Recently, more studies have used partial body [18F]FDG-PET/CT in the thyroid [40, 462].
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