La sous-estimation dans les résultats des biopsies sous IRM et les recommandations de bonne pratique

The development of breast MR has led to the development of MR-guided vacuum assisted biopsies for suspicious MR enhancement without any substratum on mammography or ultrasound. Conversely to stereotically guided biopsies mainly performed on microcalcification for which radiography of the samples allows to check the quality of the procedure and conversely to US-guided biopsies which permits to see the needle in real time, the evaluation of the quality of a procedure guided by MR is more difficult. The criteria for investigating the quality of MR procedure are delayed and include the rate of false negative and the rate of underestimation. Underestimations correspond to risk lesions including mainly atypical ductal hyperplasia, upgraded in cancer at surgery and ductal carcinoma in situ upgraded in invasive cancer at surgery. This article gives the rate of underestimation in atypical ductal hyperplasia and in ductal carcinoma in situ, as shown in the literature and in a multi-institutional French study, the Sifem study. Furthermore, this article analyses the risk factors, including epidemiological factors, histologic factors and imaging factors for underestimation. Among these, the Sifem study has identified as a risk factor of underestimation the presence of a mass at MRI. Lastly, this article discusses recommendation about the management of atypical ductal hyperplasia or ductal carcinoma in situ diagnosed by MRI-guided vacuum assisted biopsy.