Quality and consistency of clinical practice guideline recommendations for PET/CT and PET. A systematic appraisal

To systematically appraise the methodologies used for guidelines for positron emission tomography (PET) imaging and to compare the consistency of these recommendations. We searched PubMed, EMBASE, four guideline databases, and Google Scholar to identify evidence-based clinical practice guidelines pertaining to the use of PET, PET/computed tomography (CT), or PET/magnetic resonance in routine practice. We assessed the quality of each guideline using the Appraisal of Guidelines for Research and Evaluation II instrument and compared recommendations regarding indications for ${}^{18}$F-fluorodeoxyglucose (FDG) PET/CT. Thirty-five guidelines for PET imaging, published between 2008 and 2021, were included. These guidelines performed well in the domains of scope and purpose (median 80.6%, inter-quartile range [IQR] 77.8-83.3%) and clarity of presentation (median 75%, IQR 69.4-83.3%), but poorly in applicability (median 27.1%, IQR 22.9-37.5%). Recommendations for 48 indications in 13 cancers were compared. Considerable inconsistencies in the direction of whether to support the use of FDG PET/CT were observed in 10 (20.1%) indications pertaining to 8 cancer types: head and neck cancer (treatment response assessment), colorectal cancer (staging in patients with stages I-III disease), esophageal cancer (staging), breast cancer (restaging and treatment response assessment), cervical cancer (staging in patients with stage < IB2 disease and treatment response assessment), ovarian cancer (restaging), pancreatic cancer (diagnosis), and sarcoma (treatment response assessment). Current guidelines for PET imaging vary in methodological quality and provided considerably inconsistent recommendations. Efforts are needed to improve adherence to guideline development methodologies, to synthesis high-quality evidence, and to adopt standard terminologies. PROSPERO CRD42020184965. Guidelines for PET imaging provide considerably inconsistent recommendations and vary in methodological quality. It is suggested that clinicians be critical of these recommendations when applying them in practice, that guideline developers adopt more rigorous development methodologies, and that researchers prioritize research gaps identified by current guidelines.