RT Journal Article SR Electronic T1 554 Why prefer diffusion MRI over CT in diagnostics, staging and detection of recurrence in ovarian cancer patients? lnteresting illustrative cases JF International Journal of Gynecologic Cancer JO Int J Gynecol Cancer FD BMJ Publishing Group Ltd SP A249 OP A250 DO 10.1136/ijgc-2021-ESGO.427 VO 31 IS Suppl 3 A1 Härmä, K A1 Imboden, S A1 Mueller, M A1 Heverhagen, J YR 2021 UL http://ijgc.bmj.com/content/31/Suppl_3/A249.abstract AB Introduction/Background*Correct pre-operative staging and operability assessment is crucial for ovarian cancer (OC) patients’ treatment decision. Diffusion weighted MRI (DW-MRI) is a functional imaging technique, which is sensitive e.g. in detecting peritoneal, diaphragmal, liver capsular and bowel serosal carcinomatosis and has potential in the future to guide therapy assessments in personalized direction. Yet, DW-MRI is seldom used in daily clinical routine in OC.Methodology We informed the gynecologist oncologist colleagues in our ESGO certified university hospital tumor center about the 3-Tesla whole-body DW-MRI modality, possible for OC. Until now, 25 patients are referred and included to the study. Acquisition time from the neck to symphysis requires 30 minutes and the protocol does not include contrast medium. Six women were referred because of suspicion on chemical or symptomatic recurrence (REC), 10 for the follow-up stating (F-up) after cancer therapy and six for primary tumor detection (Tu-Det). Furthermore, three patients were imaged having uterine, cervical and gestational breast cancer.Result(s)*5/6 (REC), 5/10 (F-up), 4/6 (Tu-Det) showed pathologic diffusion restricted MR-graphic findings. Even MR-graphic only faint T2w but diffusion restricted bright lesions were verified to be carcinomatous intraoperative/histopathological. Apparent diffusion coefficient (ADC) values were calculated. Primary and metastatic tumor sites were reported. When operated, the MR-graphic findings were correlated with intra-operative and histopathological findings.Abstract 554 Figure 1 Conclusion*DW-MRI without contrast media is a feasible and sensitive tool in OC primary diagnostics, staging and in detecting recurrence. Change is difficult, but sometimes necessary, as also former studies of this topic show. Larger multicenter studies are required in order to investigate the impact of DW-MRI for therapy management and overall survival.