الفهرس | Only 14 pages are availabe for public view |
Abstract Summary Magnetic resonance (MR) imaging is commonly performed in the preoperative setting for breast cancer to identify the extent of disease, and to assess for both ipsilateral foci of multifocal or multicentric involvement and contralateral disease. This can significantly alter the course of treatment, from breast-conserving surgery to more extensive surgery or mastectomy. Prior to the dynamic contrast-enhanced series,precontrast imaging are performed to improve the specificity of lesion characterization by means of evaluation of blood-, fat-, and fluid-containing lesions, and depiction of susceptibility artifact–causing structures such as postbiopsy markers or clips DCIS can be hypo- to isointense on precontrast T1- weighted and fat-saturated T2-weighted images. The most commonly reported MR imaging manifestation of DCIS is clumped nonmasslike enhancement in a ductal, linear, segmental, or regional distribution. The most frequent enhancement pattern is clumped enhancement, followed by heterogeneous, homogeneous, reticular, and punctate. Summary & Conclusion 161 High-grade DCIS more frequently manifests as an enhancing mass than does intermediate or low-grade DCIS. Low-grade DCIS frequently shows non masslike enhancement or no enhancement. Two distinct patterns of neovascularization may occur in DCIS: periductal and stromal. The periductal pattern manifests as a dense rimlike network of micro-vessels adjacent to the basement membrane of a duct. The stromal pattern is characterized by a more diffuse increase in vascularity of the stroma between DCIS lesions. There is wide variability in the reported enhancement kinetic curve of DCIS, with the most common pattern being early enhancement with plateau kinetics, the plateau enhancement kinetic curve is more commonly seen than washout or progressive enhancement kinetics. No kinetic pattern is pathognomonic of a particular nuclear grade of DCIS. Thus, the image interpretation and final recommendations should be based on the morphologic characteristics instead of the enhancement kinetics of the lesion. Summary & Conclusion 161 Diffusion-weighted MRI (DWI) is an unenhanced MRI sequence that has shown promise for discriminating benign from malignant breast lesions and may yield information different from and complementary to that obtained with DCEMR. Pure DCIS lesions have higher signal intensity on DWI than normal breast tissue and have a lower mean ADC value than normal breast tissue. Non high grade lesions exhibit greater DWI signal intensity and DWI CNR than high grade lesions. MR spectroscopy appears to have a bright future in the field of breast imaging. Its role in differentiating benign from malignant lesions and in improving the specificity of breast MR imaging may result in fewer breast biopsies. Some means of MR imaging–guided biopsy is essential in a screening program to maximally benefit its sensitivity. Thus, the role of MRI in the evaluation of ductal carcinoma in situ (DCIS) has focused on two specific clinical applications. The first is the performance of MRI in the evaluation of the extent of the disease in patients with a diagnosis of DCIS, before therapeutic planning. The second Summary & Conclusion 161 application is early detection of DCIS in breast cancer screening programs. These studies have focused on patients at high risk for breast cancer in whom both mammography and MRI are recommended for screening. Conclusion: The ability of MRI to detect the presence and extent of DCIS In unequivocally significantly exceeds that of mammography or ultrasound and is associated with acceptable specificity. This improved sensitivity is particularly robust for high-grade DCIS lesions. The improved diagnostic accuracy will affect outcomes in patients at risk for and with breast cancer warrants carefulinvestigation. |