Determining the Axillary Nodal Status with 4 Current Imaging Modalities, Including 18F-FDG PET/MRI, in Newly Diagnosed Breast Cancer: A Comparative Study Using Histopathology as the Reference Standard

The purpose of this study was to compare breast MRI, thoracic MRI, thoracic F-18-FDG PET/MRI, and axillary sonography for the detection of axillary lymph node metastases in women with newly diagnosed breast cancer. Methods: This prospective double-center study included patients with newly diagnosed breast cancer between March 2018 and December 2019. Patients underwent thoracic (F-18-FDG PET/)MRI, axillary sonography, and dedicated prone breast MRI. Datasets were evaluated separately regarding nodal status (nodal-positive vs. nodal-negative). Histopathology served as the reference standard in all patients. The diagnostic performance of breast MRI, thoracic MRI, thoracic 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 4 modalities. A McNemar test was used to assess differences. Results: In total, 112 female patients (mean age, 53.04 +/- 12.6 y) were evaluated. Thoracic PET/MRI showed the highest AUC, with a value of 0.892. The AUCs for breast MRI, thoracic MRI, and sonography were 0.782, 0.814, and 0.834, respectively. Differences between thoracic PET/MRI and axillary sonography, thoracic MRI, and breast M Rlwere statistically significant (PET/MRI vs. axillary sonography, P = 0.01; PET/MRI vs. thoracic MRI, P = 0.02; PET/MRI vs. breast MRI, P = 0.03). PET/MRI showed the highest sensitivity (81.8% [36/44]; 95% CI, 67.29%-91.81%), whereas axillary sonography had the highest specificity (98.5% [65/66]; 95% CI, 91.84%-99.96%). Conclusion: F-18-FDG PET/MRI outperforms axillary sonography, breast MRI, and thoracic MRI in determining the axillary lymph node status. In a clinical setting, the combination of F-18-FDG PET/MRI and axillary sonography might be considered to provide even greater accuracy in diagnosis.

Automated summary

This study aimed to compare different imaging modalities for detecting axillary lymph node metastases in women with newly diagnosed breast cancer. The results show that F-18-FDG PET/MRI had the highest accuracy in determining axillary lymph node status, while axillary sonography had the highest specificity. In a clinical setting, combining F-18-FDG PET/MRI and axillary sonography may offer even greater diagnostic accuracy.