Role of MRI in the Diagnosis of Ductal Carcinoma In Situ: A Retrospective Study

<b>Background:</b> The use of dynamic magnetic resonance imaging (MRI) for the evaluation, detection, and characterization of ductal carcinoma in situ (DCIS) has been increasing; however, its application in this context remains controversial and uncertain. <b>Materials:</b> A retrospective study including women with pure DCIS, confirmed between January 2012 and December 2022 using ultrasound-guided core-needle biopsy (CNB) or stereotaxy-guided vacuum-assisted biopsy (VAB), was conducted. Mammography, ultrasound (US), and MRI of DCIS lesions were evaluated according to histological grade. The size of the DCIS, as assessed by mammography, US, MRI, and final surgical histopathology, was compared using Lin's concordance correlation and Bland-Altman plots. <b>Results</b>: A total of 144 women (mean age 55.5 ± 10.3 years) with histopathological diagnoses of pure DCIS and no evidence of infiltration in the percutaneous biopsy were included in the study. Microcalcifications were the most prevalent feature observed in mammography (82.63%). Round/punctate morphology was more common in low-grade lesions, while fine pleomorphic morphology was more frequent in medium- and high-grade lesions. Lesions manifesting as microcalcifications only on mammography were significantly associated with intermediate and high-nuclear grade DCIS (<i>p</i> = 0.005). The most common MRI manifestation of DCIS was non-mass enhancement (86.11%). A total of 141 lesions showed enhancement with MRI (sensibility 97.92%). There were no significant differences (<i>p</i> = 0.29) between negative and positive enhancement with MRI and the histological grade of the lesions. There were no significant differences (<i>p</i> = 0.49) between the type of enhancement curve with MRI and the histological grade. Preoperative MRI detected additional malignancies (multifocal, multicentric, or bilateral) in 35 patients (24.31%). <b>Conclusions:</b> DCIS demonstrated enhancement with MRI regardless of histological grade but overestimated the size of the lesions in low-nuclear-grade DCIS. Preoperative MRI identified additional malignancies (multifocal, multicentric, and bilateral lesions) in 24 patients (16.67%), which were confirmed by histopathological examination. These malignancies were either undetected or not visible with mammography and ultrasound. However, MRI also overestimated the size of the DCIS, leading to three unnecessary mastectomies in our study.