ROLE OF DIFFUSION-WEIGHTED IMAGING AS AN ADJUNCT TO CONTRAST-ENHANCED MRI IN ASSESSMENT OF SUSPICIOUS BREAST LESIONS

Abstract

Conventional imaging modalities as mammography and ultrasound remain the method of choice for routine screening programs and is the 1st imaging aid, but conventional assessment have well-known limitations, such as inaccurate differentiation between benign and malignant lesions and estimation of the size of malignant tumors. The sensitivity of breast MRI for the detection of cancer is the greatest of all imaging techniques and when the findings of conventional imaging are inconclusive (i.e. BI-RADS 0), MRI can be used as a problem-solving modality, it is also better at identifying the true extent of cancer when multifocal disease or ductal carcinoma in situ is present. However its reported specificity is variable. DWI if further clinical evaluation is needed represents an easy non time consuming inexpensive complementary quantitative breast imaging sequence. In addition, ADC mapping based on diffusion properties provides valuable information on benign and malignant lesions by characterizing tumor cellularity. When the sensitivity of the MRI was high, its specificity was low due to overlap in features of benign and malignant lesions. DWI had higher specificity and the ADC value was a sensitive and specific parameter in differentiating benign and malignant breast lesions. The specificity was higher for mass than non mass lesions. In Conclusion : It must be understood that DWI should be conjugated with DCE-MRI to avoid non visualization of small breast lesions, in this way it may improve the specificity of MRI for characterizing breast lesions. Moreover, DWI can be used alone in combination with T2WI for cases in whom contrast agent could not be given (e.g. pregnancy, renal dysfunction and those who have sensitivity against contrast agent). Thus, it is recommended as a part of routine preoperative examination. However; it is only of moderate value in assessment of non mass breast lesions.