Role of Magnetic Resonance Diffusion-Weighted Imaging (DWI) In Diagnosis of Breast Lesions

Abstract

Breast cancer is most common cause of cancer deaths among women worldwide. Despite the improvement in the detection of breast cancer with the widespread application of mammography and ultrasound, some breast lesions still remain difficult to diagnose and characterize, especially in dense fibroglandular breasts and in differentiating post-operative changes from recurrent masses. The sensitivity of breast MRI for the detection of cancer is the greatest of all imaging techniques especially when the findings of conventional imaging are inconclusive. MRI can be used as a problem-solving modality, it is also better at identifying the true extent of cancer and help in cancer staging when multifocal disease or ductal carcinoma in situ is present. However its reported specificity is variable. Con¬sequently, there has been considerable interest in the development of adjunct MR imaging methods to improve the specificity of dynamic contrast-enhanced breast MR imaging. Diffusion-weighted breast imaging is being investigated for its potential to improve breast disease diagnosis. It is desirable that a diagnostic test in the breast should eitherrule in or rule out malignancy.The applicationof additional DWI toMRI protocols is fast and does not requirefurther preparations. In this study we attempted to investigate the validity of DWI and ADC measurements in differentiating benign and malignant breast lesions and further correlation of the study results with histopathological data and/ or follow up. The study included 40 patients. All patients underwent contrast enhanced-MRI, DWI and ADC values measurements with documentation of findings. We found that DWI and ADC measurement increased the specificity of the breast MRI in characterization of different breast lesions and was of great help in differentiating between post-therapeutic changes from recurrent breast cancers. It also can reduce the number of false-positive results and associated unnecessary biopsies. The calculated ADC value is clearly affected by the scanning parameters used for DWI. That is the reason for the different cutoff values found for the discrimination of the malignant from benign lesions among different studies. So, all MRI centres should determine their own cutoff values according to the DWI sequence used for breast imaging.