Purpose: To evaluate breast magnetic resonance imaging (MRI) for cancer staging and surgical planning in patients with known breast cancer, and to evaluate recurrence rates at long-term follow-up.
Methods and materials: Institutional review board approval and patient consent were obtained. Preoperative MRI with 0.1 mmol/kg gadobenate dimeglumine (MultiHance) was performed in 203/274 women with confirmed breast cancer. The sensitivity, accuracy, and positive predictive value of MRI compared with mammography/ultrasound for malignant lesion detection were calculated, and the effect of MRI on surgical decision making evaluated. The cancer recurrence rate was determined for 172 patients with available 2- to 8-year follow-up data.
Results: Mammography/ultrasound detected 229 suspicious lesions. Breast MRI detected 159 additional lesions in 48/203 (23.6%) patients; of which 110/110 were correctly classified as malignant and 28/49 as benign, giving sensitivity, accuracy, and positive predictive values for malignant lesion detection of 100% (110/110), 86.8% (138/159), and 84.0% (110/131), respectively. MRI revealed unsuspected multifocal, multicentric, and synchronous contralateral lesions in 7/48, 16/48, and 16/48 patients, respectively, and pectoralis muscle infiltration in 3/38 patients. In 6/48 women, MRI revealed lesions not seen on conventional imaging (n = 5) or discounted suspected multifocal disease (n = 1). Therapy was changed for 50/203 (24.6%) patients: 38 patients underwent more extensive surgery and 12 less extensive surgery. Six (3.5%) recurrences occurred, in all cases at >4 years.
Conclusion: Breast MRI positively affects patient management and is recommended for mapping tumor extent in patients with newly diagnosed cancer. The cancer recurrence rate at long-term follow-up after MRI is low.