Prospective evaluation of whole-body MRI and 18F-FDG PET/MRI in N and M staging of primary breast cancer patients
Nils Martin Bruckmann, Lino M. Sawicki, Julian Kirchner, Ole Martin, Lale Umutlu, Ken Herrmann, Wolfgang P. Fendler, Ann‐Kathrin Bittner, Oliver Hoffmann, Svjetlana Mohrmann, Frederic Dietzel, Marc Ingenwerth, Benedikt M. Schaarschmidt, Yan Li, Bernd Kowall, Andreas Stang, Gerald Antoch, Christian Buchbender
Abstract
Abstract Objectives To evaluate and compare the diagnostic potential of whole-body MRI and whole-body 18 F-FDG PET/MRI for N and M staging in newly diagnosed, histopathologically proven breast cancer. Material and methods A total of 104 patients (age 53.4 ± 12.5) with newly diagnosed, histopathologically proven breast cancer were enrolled in this study prospectively. All patients underwent a whole-body 18 F-FDG PET/MRI. MRI and 18 F-FDG PET/MRI datasets were evaluated separately regarding lesion count, lesion localization, and lesion characterization (malignant/benign) as well as the diagnostic confidence (5-point ordinal scale, 1–5). The N and M stages were assessed according to the eighth edition of the American Joint Committee on Cancer staging manual in MRI datasets alone and in 18 F-FDG PET/MRI datasets, respectively. In the majority of lesions histopathology served as the reference standard. The remaining lesions were followed-up by imaging and clinical examination. Separately for nodal-positive and nodal-negative women, a McNemar chi 2 test was performed to compare sensitivity and specificity of the N and M stages between 18 F-FDG PET/MRI and MRI. Differences in diagnostic confidence scores were assessed by Wilcoxon signed rank test. Results MRI determined the N stage correctly in 78 of 104 (75%) patients with a sensitivity of 62.3% (95% CI: 0.48–0.75), a specificity of 88.2% (95% CI: 0.76–0.96), a PPV (positive predictive value) of 84.6% % (95% CI: 69.5–0.94), and a NPV (negative predictive value) of 69.2% (95% CI: 0.57–0.8). Corresponding results for 18 F-FDG PET/MRI were 87/104 (83.7%), 75.5% (95% CI: 0.62–0.86), 92.2% (0.81–0.98), 90% (0.78–0.97), and 78.3% (0.66–0.88), showing a significantly better sensitivity of 18 F-FDG PET/MRI determining malignant lymph nodes ( p = 0.008). The M stage was identified correctly in MRI and 18 F-FDG PET/MRI in 100 of 104 patients (96.2%). Both modalities correctly staged all 7 patients with distant metastases, leading to false-positive findings in 4 patients in each modality (3.8%). In a lesion-based analysis, 18 F-FDG PET/MRI showed a significantly better performance in correctly determining malignant lesions (85.8% vs. 67.1%, difference 18.7% (95% CI: 0.13–0.26), p < 0.0001) and offered a superior diagnostic confidence compared with MRI alone (4.1 ± 0.7 vs. 3.4 ± 0.7, p < 0.0001). Conclusion 18 F-FDG PET/MRI has a better diagnostic accuracy for N staging in primary breast cancer patients and provides a significantly higher diagnostic confidence in lesion characterization than MRI alone. But both modalities bear the risk to overestimate the M stage.