MR imaging appearance of noncalcified and calcified DCIS

To evaluate the MR appearance of noncalcified ductal carcinoma in situ (DCIS), with comparison to calcified DCIS. A retrospective, IRB-approved review of all DCIS diagnosed via MR biopsy between 2007 and 2011 was performed. DCIS was categorized as noncalcified based on the absence of calcifications on mammography and specimen radiography. MR morphology (focus, mass, nonmass enhancement [NME]) and enhancement kinetics (initial and delayed) for noncalcified DCIS were recorded and compared based on nuclear grade (1-3), size (<1.5 cm, 1.5-5 cm, >5 cm), and presence of necrosis. Imaging features of noncalcified and calcified DCIS were also compared. 115 cases of MR biopsy-proven DCIS were identified: 65 (56%) noncalcified and 50 (44%) calcified. For noncalcified DCIS, NME morphology was more common than mass or focus (60% vs 30.8% and 9.2%). There was a significant association between morphology and enhancement kinetics, with NME more likely demonstrating medium and persistent kinetics, and foci or masses demonstrating rapid and plateau or washout kinetics (P < .05). There was also a significant association between morphology and nuclear grade, with NME more likely seen with grade 3 DCIS (P = .024), and between size and initial enhancement, with lesions <1.5 cm more likely to have rapid initial enhancement (P = .0036). No significant difference was identified between calcified and noncalcified DCIS in terms of morphology, enhancement characteristics, nuclear grade, or presence of necrosis. The MR appearance of noncalcified DCIS closely mirrors that of calcified DCIS. Recognizing these imaging features may allow for improved identification of this MRI-detected abnormality, even in the absence of calcifications.