Lymph node dissection to diagnose metastatic spread of breast cancer often causes painful underarm ache that can last for months or even decades. The introduction of ultrasound-guided fine needle aspiration (US-FNA), enabling the dissection of only a single lymph node, proved to be effective and less invasive and As a result, it has become widely accepted for preoperative axillary lymph node staging.
However, a 2014 meta-analysis undertaken by radiologists at the University Medical Center Utrecht in the Netherlands revealed that ultrasound (US) and US-FNA had a sensitivity of 50% and a false-negative rate of 25%.1 Because breast MRI is frequently used to evaluate tumor extent prior to surgery as a component of treatment planning, a team of Korean researchers conducted a study to evaluate whether adding MRI to US and US-FNA could reduce the false-negative rate in the diagnosis of axilliary lymph node metastasis.
At Severance Hospital in Seoul, all patients who have suspicious mammography findings undergo a US exam to evaluate their preoperative axillary lymph node status. When patients have positive US findings of axillary lymph node metastasis — such as loss of fat hilum, irregular or found shape, cortical thickening of more than 3 mm, or increased non-hilar peripheral blood flow — an US-FNA exam is performed. Pathologists analyze cells acquired from this procedure to determine if they are positive or negative for metastasis. In cases where patients have a breast MRI following breast cancer diagnosis, where there is suspicion of axillary lymph node metastasis, a second US and possibly a second US-FNA exam is performed.
Lead author S.J. Hyun, M.D, and colleagues in the department of radiology at the Breast Cancer Clinic at Severance Hospital, Yonsei University College of Medicine, conducted a retrospective study from March 2012 to February 2013, which included 497 patients diagnosed with breast cancer who had mammography, ultrasound (US and US-FNA) and breast MRI followed by surgery. The researchers calculated diagnostic performance including the false negative rate for US and US-FNA with and without MRI. A total of 159 of these patients were diagnosed with axillary lymph node metastasis. Of these, 92 (or 57.9%) were diagnosed from the US and US-FNA exams alone. But with the addition of images from a breast MRI, an additional 6 patients were diagnosed with metastasis. The false negative rate was improved by the addition of MRI by 3.7% (42.1% with and 38.4% without). Also, the combination of US and US-FNA with MRI produced a negative predictive value of 98% for patients with N2 and N3 disease.
The authors stated that the cost of breast MRI may be prohibitive if used solely for axillary lymph node diagnosis, but when ordered as part of treatment planning, it becomes a valuable tool for the detection of abnormal axillary lymph nodes. “Breast MRI, in combination with US and US-FNA increases sensitivity and decreases false negative rate while retaining high specificity. It provides radiologists with an opportunity to reevaluate axillary lymph nodes,” they concluded.
Adding MRI to US reduces false-negative rate of axillary lymph node metastasis diagnosis in breast cancer patients. Appl Radiol.
Cynthia E. Keen is a New York City area-based medical writer specializing in clinical subjects and healthcare technology. She writes feature articles for Applied Radiology and the contents of the Applied Radiology newsletter.