What is involved in a comprehensive breast MRI service? Implications for service provision

Introduction

MRI as an adjunct to triple assessment is well established, but often identifies additional lesions within the breast necessitating further characterisation. This study addresses the additional investigations generated by MRI.

Methods

A retrospective review of the MRI database between 2006 and 2009 identifying patients requiring investigations post MRI.

Results

Over 4 years, 1,119 MRIs were performed on 717 patients, with 102 recalled for second-look ultrasound. Three patients were lost to follow-up. A total 124 incidental lesions were identified on MRI. Ultrasound identified 68 lesions, with definitive diagnosis following core biopsy/FNAC (62), surgery (two) core biopsy + repeat MRI (one) and MRI biopsy (three). Twenty-two lesions not identified by USS were assessed with X-ray-guided biopsy (two), MRI biopsy (13), interval MRI (five) or surgery (two). Nineteen MRI lesions following normal ultrasound had routine follow-up. Fifteen lesions (12 patients) did not have follow-up USS, as recommended following MDT discussion. Sixty lesions (44 patients) were malignant; MRI identified a primary in four patients presenting with lymphadenopathy and in 39 patients identified additional foci that changed management. Malignant lesions were identified on US biopsy/FNAC (38), X-ray-guided biopsy (one), MRI biopsy (seven) and surgery (14).

Conclusions

MRI identifies additional foci in 14% of patients. Malignant lesions will be identified in 43% of patients recalled. Comparison with 2005 data identifies a decreased recall rate and an increased cancer detection rate. Fifty per cent of additional lesions identified by MRI are malignant, of which 77% were confirmed preoperatively. Provision of a comprehensive breast MRI service must consider the resources needed to deliver the additional diagnostic investigations required.