Role of Breast Magnetic Resonance Imaging in the Preoperative Assessment and Its Impact on Surgical Management of Patients with Newly Diagnosed Breast Cancer

Objective: To determine the role of breast magnetic resonance imaging in the preoperative assessment of patients with newly diagnosed breast cancer and its impact on surgical management. Methods: In all, 22 patients with recently diagnosed breast cancer underwent preoperative magnetic resonance imaging and subsequent surgery or biopsy between 1 January 2010 and 30 June 2011. Patients with a change from initial planned surgical treatment to final surgical treatment based on additional mammographically occult magnetic resonance imaging findings were identified. Results: Additional magnetic resonance imaging findings were found in 10 (45%) of the 22 patients; in eight there were additional suspicious lesions, and in two more extensive local disease became evident. In seven (32%) of the patients, there was a change in the initial planned surgical management owing to additional ipsilateral magnetic resonance imaging findings. One (5%) of the patients had contralateral surgery due to detection of synchronous contralateral cancer, and in five others additional suspicious lesions were only noted on magnetic resonance imaging that were confirmed to be malignant, giving a positive predictive value of 63%. In two (9%) of the 22 patients, the index tumours appeared significantly larger on magnetic resonance imaging than in mammograms, which changed the initial planned surgical management from breast conservation to mastectomy; there being less than one month between mammography and magnetic resonance imaging. For these two patients, calculated average tumour size underestimation on mammograms was 15.9 cm(3) (range, 11.9 -19.9 cm(3)). Another 23% (5/22) had additional mammographically occult cancers diagnosed by magnetic resonance imaging, with 18% having additional site(s) of ipsilateral cancer and 5% having unsuspected contralateral cancer. Conclusion: Breast magnetic resonance imaging is a valuable tool in determining surgical management and detecting additional mammographically occult cancers in newly diagnosed breast cancer patients.