Use of Breast Magnetic Resonance Imaging and Ultrasonography for Identifying Nonpalpable Axillae Metastases in Newly Diagnosed Breast Cancer Patients.

BACKGROUND: The metastasis of axillary lymph node (ALNs) is a critical step in the initial cancer staging of newly diagnosed breast cancer (BC) patients. Various imaging modalities can enhance the sensitivity of clinical examination in assessing the ALN status.

PATIENTS AND METHODS: We enrolled 135 patients with BC, confirmed via histopathology, including 4 bilateral BC cases. A total of 139 ipsilateral ALNs adjacent to the breast lesion were examined via physical examination, ultrasonography (US), and magnetic resonance imaging (MRI); of these, 100 were nonpalpable ALNs, as determined by experienced breast surgeons and physicians. The relative size parameters on MRI and US images were recorded. Receiver operating characteristic (ROC) analyses were conducted, and the area under the ROC curve (AUC) was compared.

RESULTS: Of 139 ALNs, 67 (48%) were malignant and 72 (52%) were benign on pathological examination. In all of the ALNs, the US short diameter appeared to be the most discriminative quantitative measurement for detecting positive findings (AUC, 0.854). In nonpalpable ALNs as well, the US short diameter exhibited the greatest discriminability (AUC, 0.746). However, the 2-dimensional and 3-dimensional parameters on MRI did not exhibit any significant differences between the enrolled and nonpalpable ALNs (P > .05).

CONCLUSION: The shortest diameter on US exhibited better discriminative ability than MRI for predicting positive ALNs in nonpalpable axillae. Moreover, the 2-dimensional and 3-dimensional parameters on MRI did not differ in terms of discriminability.