Contrast-enhanced MR imaging of breast lesions and effect on treatment

To assess the value of local staging with preoperative magnetic resonance imaging (MRI) in patients with suspect breast lesions and the effect on therapeutic approach.

Two hundred and four consecutive women with suspect breast lesions on clinical examination (CE) and/or mammography (MX) and/or ultrasound (US) underwent preoperative contrast-enhanced MRI. Detection of multifocal, multicentric and bilateral breast cancer by all three imaging modalities was evaluated. Results of preoperative breast MRI were discussed with the treating surgeons. The type of therapeutic change after preoperative MRI was marked on a questionnaire (none, additional fine needle aspiration, core biopsy, open biopsy, wider excision, mastectomy) and considered 'necessary' or 'unnecessary' using final histopathological results as gold standard.

In 170 patients, breast cancer was diagnosed. MRI detected 96% of multifocal disease and 95% of multicentric disease, whereas MX depicted 37 and 18%, and US 41 and 9% of them, respectively. All bilateral breast cancers were seen on MRI; both MX and US detected 56%. Findings of more extensive disease and unsuspected multiple breast cancer foci identified on MRI only, changed the therapeutic approach correctly in 30.6% of breast cancer patients. Nine unnecessary wider excisions and three unnecessary FNA/core biopsies were performed because MRI overestimated the number or size of malignant lesions.

Preoperative breast MRI is an important adjunct to conventional imaging in the loco-regional staging of breast cancer and a useful tool in treatment planning.