Comparison of MRI features of different grades of DCIS and invasive carcinoma of the breast.

JBR–BTR, 2005, 88: 225-232.Ductal carcinoma in situ (DCIS) isdefined as a proliferation of malig-nant epithelial cells within the ductswithout extension across the base-ment membrane. It is considered aprecursor of invasive carcinoma.Most invasive carcinomas are pre-ceded by DCIS, but not all patientswith DCIS will develop an invasivecarcinoma. Local recurrence afterlumpectomy for DCIS is a majorconcern and is related to residualdisease in the breast (1). After breastconserving surgery for DCIS, 50% ofrecurrences will be invasive carcino-mas (2). DCIS is a heterogeneousgroup of carcinomas in terms ofhistopathology and different grad-ing systems have been used. In 1995Silverstein applied the Van Nuysclassification for DCIS: three groupsof DCIS were defined by the pres-ence or absence of high nucleargrade and comedo-type necrosis:grade I = non-high- grade DCIS with-out comedo-type necrosis, grade II =non-high-grade DCIS with comedo-type necrosis, III = high-grade DCISwith or without comedo-type necro-sis (3). It is assumed that overallprognosis, which means risk of pro-gression into invasive carcinomaand recurrence rate, depends on thehistologic grade, the size of thelesion and the adequacy of the exci-sion (4). Excision margin width andtumor grade (by Van Nuys gradingor simple nuclear grading) were theonly independent risk factors forlocal recurrence in a report ofBoland et al. on 237 patients withDCIS (5). Of these, free margin widthwas the most important factor inpredicting recurrence. This makespreoperative estimation of tumorextension and detection of all focimandatory before breast conservingsurgery is performed. Sensitivity of MR mammographyfor DCIS is lower than for invasivecarcinomas, ranging from 58-100%in the literature (6-20). Lack of a uniform pattern ofenhancement could be a reason forthe lower detection rate (14).Described MR features of DCIS areductal enhancement, clumpedenhancement and segmentalenhancement (21), although someDCIS present as a mass (22). There issome evidence that with knowledgeof these features and after correla-tion with mammography and ultra-sound, a higher detection rate canbe obtained (20). MR mammogra-phy can give a good estimate of theextent of DCIS and can detect multi-focal lesions (9, 11, 17).In this study, we compared thedetection rate of histopathologicalyproven DCIS by mammography,ultrasound and MR and correlatedthe extent of DCIS measured oneach of these 3 imaging modalitieswith the diameter measured onhistopathology.We also studied whether MR candifferentiate between DCIS andinvasive carcinoma. Therefore, wecompared MR features of differenttypes of DCIS with those of invasivecarcinomas in a series of consecu-tive patients with breast cancer whoreceived a preoperative MR.