The Role of Pre-Operative Magnetic Resonance Mammography in Obese Women with Suspected Breast Cancer

Abstract

OBJECTIVE: To high-lighten the role of MR mammography as a pilot pre-operative modality in the staging of breast cancer and its impact on surgical planning and management; aiming to decrease morbidity and mortality of this increasingly spreading cancer. In addition, to clarify the assessment of the relationship between the types of obesity and staging breast cancer. Moreover, to evaluate the diagnostic validity of breast MRI in discriminating benign from malignant lesions in women with suspected breast cancer histopathologic findings used as the golden standard. PATIENTS AND METHODS: Contrast-enhanced bilateral breast MRI was performed on 60 women with suspected breast cancer with indeterminate imaging findings by mammography and/or ultrasonography. Lesions detected by MRI that could represent potential malignancies in both breasts were evaluated. Morphologic assessment and kinetic analysis (contrast enhancement) were performed on each lesion using dedicated postprocessing and display software. Functional MR tools were used in few cases (6 cases) to help in the differential diagnosis between malignant and benign of suspicious lesions detected at conventional MRI. All patients underwent clinical and radiological evaluation followed by Contrast-enhanced bilateral breast MRI using 1.5-tesla superconductive Philips scanner and General Electric Medical Systems. The diagnostic images were evaluated as regard lesion morphology (size, shape, margin type, enhancement pattern), signal intensity parameters (time to peak enhancement, maximum slope of enhancement curve, washout), and the BIRADS categories. Results of the contrast enhanced bilateral breast MRI of the 60 patients were all reported and compared with the histopathalogical biopsy. RESULTS: A total of 60 patients presented with suspected breast cancer were included in the study with age ranging from 38 to 75 years old. 22 of the studied population had benign findings, while 38 of the patients were diagnosed as malignant. (18 patients IDC, 6 patients Invasive Lobular Carcinoma, 3 patient Mucinous carcinoma, no patients Medullary carcinoma and 4 patients Insitu cancer). In this study population the sensitivity, specificity, positive and negative predictive values of mammography were found to be 51.6%, 88.4%, 66.7%, and 80.3% respectively. Overall accuracy of mammography was 77%. Among the 38 cases diagnosed by sonomammography as malignant or with irregular densities, 16 turned out to be benign by histopathological evaluation (false +ve), while among the 22 cases diagnosed by sonomammography to be benign lesions or non-conclusive studies (dense), 7 were proved to be malignant by histopathological evaluation (false –ve). The sensitivity, specificity, positive and negative predictive values of MRI for occult breast lesions in high risk patients included in the study, were found to be 100%, 93%, 86%, and 100% respectively. Overall accuracy of MRI breast was 95%. Among the 38 cases diagnosed by MRI as malignant, there was no false +ve, while among the 22 cases diagnosed by MRI to be benign lesions, 7 cases were proved to be malignant by histopathological evaluation (false –ve). Therefore breast MRI had higher sensitivity than specificity but general speaking it is considered highly valid with high specificity also. Due to the limited number of cases in this study, there was a trend in relation of obesity (BMI) to breast cancer, malignancy rate 55.3% in obese women and 44.7% in non-obese women. CONCLUSION: From our study, we conclude that MR imaging of the breast in obese women , is a rapidly evolving modality of excellent sensitivity in detection of breast cancer. The basic drawback of this modality was its low specificity for breast malignancy. However, multiple studies including this study have shown that with the improvement in equipment and technique there is gradual increase in specificity.