18F-FDG PET/MRI in endometrial cancer: systematic review and meta-analysis

Purpose To present the progresses of hybrid 18 F-FDG PET/MR imaging in the staging/restaging setting of endometrial cancer (EC), with particular focus on performance evaluations and biomarker analyses. Methods Original articles were searched on PubMed, EMBASE and Web of Science, until March 2021. Reports were screened to select studies using simultaneous PET/MR acquisition, discarding those using sequential protocols. Studies including heterogeneous and/or homogeneous cohorts of pelvic tumor patients were considered, while works for which the exact number of EC patients was not reported have been discarded. Evaluations of selected articles were focused on (i) performance evaluation, (ii) biomarker analysis. The quality of papers was assessed by QUADAS-2. Results Eleven articles involving 18 F-FDG PET/MRI EC-related objectives were selected. The quality of papers was generally high. Compared to other imaging techniques, PET/MRI seems to show a higher diagnostic accuracy in detecting soft tissue invasion and abdominopelvic metastases from primary EC. Among different PET- and MRI-derived biomarkers, SUV-to-ADC ratio seems to be the most informative index in differentiating EC aggressiveness. Moreover, PET/MRI provided the chance to differentiate post-therapeutic changes from local relapse, and to detect small, morphologically unsuspicious lymph node metastases in patients with recurrent EC, with better performances compared to other imaging modalities. Conclusions Preliminary results demonstrated how 18 F-FDG PET/MRI could be a valid imaging technique in patients with EC, both in staging and restaging, also considering the limited radiation exposure. From the limited availability of the existing literature, it is clear that further prospective trials on larger and homogeneous cohorts are needed.