Diagnostic Value of Diffusion-Weighted Imaging in Simultaneous ¹⁸F-FDG PET/MR Imaging for Whole-Body Staging of Women with Pelvic Malignancies

Abstract

The 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. Methods: Forty-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. Results: Among 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). Conclusion: DWI 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.

Diagnostic role of 18F-FDG PET/MRI in patients with gynecological malignancies of the pelvis: A systematic review and meta-analysis

“…The pooled results of sensitivity, specificity, LR+, LR- and the AUC implied that PET/MRI had an outstanding performance for assessment of metastasis to these sites [26, 34]. These results were in line with the results of studies included in this meta-analysis and previously published data [27, 30]. To achieve the best patient management for gynecological cancers, high-quality imaging technique of early detection and evaluation is essential.…”

“…The remaining 145 candidate studies were downloaded and assessed for eligibility, and 138 articles were further removed. Eventually, seven studies were eligible in our research [27–33]. There were two authors each one of whom has published three articles, the patient samples of these studies with the same author(s) were not completely same and they presented different data concerning subgroup analysis.…”

Recent Developments in Combined PET/MRI

“…There have several articles examining the utility of PET/MR in thoracic tumors with findings suggesting that FDG PET/MR is superior to FDG PET/CT [67][68][69][70][71]. While there has been promise in the use of whole body diffusion-weighted imaging (DWI) with PET/MR in malignancies such as lymphoma [72], and head and neck cancers [73], one recent study in primary or recurrent gynecologic tumors found DWI did not have any diagnostic benefit for whole-body staging [74] .…”

Current Status of Hybrid PET/MRI in Oncologic Imaging

“…For example, in a study of 34 women undergoing whole-body staging for suspected recurrence of cervical or ovarian cancer, FDG PET/MRI accurately identified 98.9% of malignant lesions, compared with 88.8% by MRI alone, and had significantly higher lesion contrast and diagnostic confidence in the detection of malignant lesions compared with MRI alone [71]. In an additional study of 122 suspected lesions in 48 women undergoing staging for gynecologic malignancy, whole-body FDG PET/MRI achieved over 90% accuracy for identification of malignant lesions [72]. …”