• Johannes Grueneisen, Benedikt Michael Schaarschmidt, Karsten Beiderwellen, Antonia Schulze-Hagen, Martin Heubner, Sonja Kinner, Michael Forsting, Thomas Lauenstein, Verena Ruhlmann, and Lale Umutlu.
• Department of Diagnostic and Interventional Radiology and Neuroradiology, University Hospital Essen, University of Duisburg-Essen, Essen, Germany Johannes.grueneisen@uk-essen.de.
• J. Nucl. Med. 2014 Dec 1; 55 (12): 1930-5.

UnlabelledThe aim of this study was to assess the diagnostic benefit of diffusion-weighted imaging (DWI) in an (18)F-FDG PET/MR imaging protocol for whole-body staging of women with primary or recurrent malignancies of the pelvis.MethodsForty-eight patients with a primary pelvic malignancy or suspected recurrence of a pelvic malignancy were included in our study. All patients underwent a whole-body (18)F-FDG PET/MR imaging examination that included DWI. Two radiologists separately evaluated the PET/MR imaging datasets without DWI followed by a second interpretation with DWI. First, both readers identified all primary tumors, as well as lymph node and distant metastases. In a second session, PET and DWI data were assessed qualitatively. Image interpretation comprised lesion conspicuity defined as visual lesion-to-background contrast (4-point ordinal scale) and diagnostic confidence (3-point ordinal scale) for all tumors. The results from histopathologic examination and cross-sectional imaging follow-up (≥6 mo) were used as the reference standard. Statistical analysis was performed to assess the significance of differences between obtained values.ResultsAmong the 122 suspected lesions seen, 98 (80.3%) were considered malignant. PET/MR imaging without DWI had a sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of 92.9%, 87.5%, 96.8%, 75.0%, and 91.8%, respectively, for the detection of malignant lesions. PET/MR imaging with DWI had slightly higher values (94.9%, 83.3%, 95.9%, 80.0%, and 92.6%, respectively), but the difference was not significant (P > 0.05). In the qualitative assessment of lesion-to-background contrast, PET had significantly (P < 0.05) higher values (3.79 ± 0.58) than DWI (3.63 ± 0.77). Furthermore, significantly (P < 0.05) higher scores were found for diagnostic confidence using PET (2.68 ± 0.64) for the determination of malignant lesions, when compared with DWI (2.53 ± 0.69).ConclusionDWI in PET/MR imaging has no diagnostic benefit for whole-body staging of women with pelvic malignancies. The omission of DWI for staging or restaging gynecologic cancer may significantly reduce examination times, thus increasing patient comfort without a relevant decrease in diagnostic competence.© 2014 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

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