Determining the Axillary Nodal Status with 4 Current Imaging Modalities, Including <sup>18</sup>F-FDG PET/MRI, in Newly Diagnosed Breast Cancer: A Comparative Study Using Histopathology as the Reference Standard
Janna Morawitz, Nils Martin Bruckmann, Frederic Dietzel, T. Ullrich, Ann‐Kathrin Bittner, Oliver Hoffmann, Svjetlana Mohrmann, Lena Häberle, Marc Ingenwerth, Lale Umutlu, Wolfgang P. Fendler, Tanja Fehm, Ken Herrmann, Gerald Antoch, Lino M. Sawicki, Julian Kirchner
Abstract
<b>Purpose:</b> To compare breast magnetic resonance imaging (MRI), thoracal MRI, thoracal <sup>18</sup>F-fluorodeoxyglucose positron emission tomography (<sup>18</sup>F-FDG PET)/MRI and axillary sonography for the detection of axillary lymph node metastases in women with newly diagnosed breast cancer. <b>Materials and Methods:</b> This prospective double-center study included patients with newly diagnosed breast cancer between March 2018 and December 2019. Patients underwent thoracal (<sup>18</sup>F-FDG PET/)MRI, axillary sonography, and dedicated prone breast MRI. Datasets were evaluated separately regarding nodal status (nodal+ vs. nodal-). Histopathology served as reference standard in all patients. The diagnostic performance of breast MRI, thoracal MRI, thoracal PET/MRI and axillary sonography in detecting nodal positive patients was tested by creating receiver-operating-characteristic curves (ROC) with a calculated area under the curve (AUC). Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated for all four modalities. A McNemar test was used to assess differences. <b>Results:</b> 112 female patients (mean age 53.04 ± 12.6 years) were evaluated. Thoracal PET/MRI showed the highest ROC-AUC with a value of 0.892. The AUC for breast MRI, thoracal MRI and sonography were 0.782, 0.814 and 0.834, respectively. Differences between thoracal PET/MRI and axillary sonography, thoracal MRI and breast MRI were statistically significant (PET/MRI vs. axillary sonography, <i>P</i> = 0.01; PET/MRI vs. thoracal MRI, <i>P</i> = 0.02; PET/MRI vs. breast MRI, <i>P</i> = 0.03). PET/MRI showed the highest sensitivity (81.8%, 36/44) (95%-CI: 67.29-91.81%) while axillary sonography had the highest specificity (98.5%, 65/66), 95%-CI: 91.84-99.96%). <b>Conclusion:</b><sup>18</sup>F-FDG PET/MRI outperforms axillary sonography, breast MRI and thoracal MRI in determining the axillary lymph node status. In a clinical setting, the combination of <sup>18</sup>F-FDG PET/MRI and axillary sonography might be considered to provide even more accuracy in diagnosis.