A service evaluation of the accuracy of axillary ultrasound and MRI in determining lymph node metastasis in patients with breast cancer

Purpose: Axillary lymph node metastasis is seen as a key prognostic factor for breast cancer patients. [1] Pre-operative diagnosis of axillary lymph node metastasis can ensure patients receive the appropriate axillary surgery and can prevent the need for further surgery. [2] This study assessed the accuracy of ultrasound, MRI and ultrasound guided core biopsy in diagnosing axillary lymph node metastasis pre-operatively. The results will aim to refine our current clinical practice. Methods: Ultrasound and MRI data was retrospectively analysed from breast cancer cases diagnosed between January 2017 and December 2019. The results were correlated to the final histological outcomes from the surgery. Results: Two hundred and fifty eight cases were included in the study, 107 (41.5%) had evidence of lymph node metastasis on final histology. Ultrasound was compared to MRI to establish which imaging modality was most accurate at detecting lymph node metastasis. Ultrasound was demonstrated to have a sensitivity of 67%, specificity of 87%, PPV 79%, NPV 79% and an Accuracy of 79%. MRI was demonstrated to have a sensitivity of 76%, specificity of 84%, PPV 77%, NPV 83% and an Accuracy of 80.6%. 103 of the cases had ultrasound guided core biopsy of an abnormal node to establish lymph node metastasis. The overall sensitivity of lymph node core biopsies was 86%, specificity was 100%, PPV 100%, NPV 68% and accuracy 89.3%. Conclusion: There was no statistical difference between the performance of ultrasound to MRI in the detection of lymph node metastasis. No change in clinical practice