The predictive value of lymph node status pre-operation by ultrasound and MRI in early and newly diagnosed breast cancer

Accurate pre-operative assessment of axillary lymph node status is key for planning surgeries in early and newly diagnosed breast cancer. Ultrasound (US) and magnetic resonance imaging (MRI) are widely used, but their performance is inconsistent across studies. This meta-analysis evaluates and compares the predictive performance of MRI and US for pre-operative lymph node metastasis in early and newly diagnosed breast cancer. We searched PubMed/MEDLINE, Embase, Scopus, and Web of Science (inception-31 December 2025) for studies on diagnostic performance in preoperative axillary staging using ultrasound and/or MRI. Two independent reviewers extracted or reconstructed true positive, true negative, false positive, false negative, and applied QUADAS-2. Sensitivity and specificity were pooled with random-effects GLMM, with direct comparisons and prevalence-based predictive values. Twenty-nine studies (n = 8,544) were included. Pooled sensitivity/specificity were 61.1%/92.0% for MRI and 59.8%/90.3% for ultrasound, yielding LR + 7.64 vs. 6.19 and DOR 18.1 vs. 13.9. HSROC AUCs were 0.863 (MRI) and 0.843 (ultrasound). In paired cohorts (k = 12), sensitivity did not differ, and MRI showed a non-significant specificity advantage. MRI and ultrasound showed comparable, moderate sensitivity and high specificity for preoperative axillary metastasis. MRI tended toward higher specificity and positive predictive value, whereas sensitivity did not differ in paired studies. Imaging can guide triage, but histopathology remains necessary for definitive staging.