Magenetic Resonance Imaging of the Breast: Radiologic-Pathologic Correlation
J Obermeyer, N Wadhwani, D Bova, S Sarker, K Rychlik, A Salhadar, C Ersahin, PB Rajan. Loyola University Chicago Medical Center, Maywood, IL
Background: Magnetic Resonance Imaging (MRI) of the breast has been increasingly used in diagnosing occult cancers, for staging purposes and in assessing response to neoadjuvant chemo/hormonal therapy. MRI's high cost and low specificity restricted its use in routine breast cancer screening. This pilot study focuses on the role of MRI in (1) detecting multifocal/multicentric disease and (2) its utility in the management of patients with newly diganosed breast cancer.
Design: Pathology department database and electronic patients' medical record were searched to select patients who had undergone mastectomy and who had pre-operative breast MRI examination at Loyola University Chicago Medical Center during the period July 2007 through June 2008. We systematically reviewed the accuracy of MRI in detecting multifocal and / or multicentric cancers not identified on conventional imaging (mammography and ultrasound). We estimated positive predictive value (PPV) and sensitivity, and also the proportion of women whose treatment were altered due to MRI findings. Interclass Correlation Coefficient is used for statistical analysis.
Results: There were a total of 59 patients who underwent mastectomy as a definitive treatment and who had pre-operative MRI of the breast as part of the management of breat cancer. Seven patients were excluded due to pre-operative neoadjuvant therapy. In contrast to mammography and ultrasound imaging, MRI detected additional lesions in 16 patients (27 %) which affected the surgical management. Pathological lesion size ranged from 0.4 to 6.2 cm (median 1.5 cm).In this analysis, positive predictive value for MRI is calculated as 93% with a sensitivity of 91%. False positive rate is 6% and false negative rate is 8%. There is a statistically significant correlation between MRI findings and pathological findings (p<0.003).
Conclusions: MRI imaging results in mastectomy as a definitive treatment in 27% of women by identifying additional cancers. Breast MRI significantly increases rate of mastectomy and the use of systemic therapy because of its accuracy in evaluating the extent of the disease. MRI of the breast is especially useful in detecting unsuspected mammographically and ultrasonologically occult ductal carcinoma in situ. Randomized clinical trials are needed to determine the value of MRI in detecting additional tumors which changes surgical management in women with breast cancer.
Wednesday, March 11, 2009 1:00 PM
Poster Session VI # 29, Wednesday Afternoon