Objective: To evaluate the concordance between the breast MRI findings and the histologic findings for the size and extension of pure ductal carcinoma in situ (DCIS) and to compare this concordance with that of conventional techniques (mammography and ultrasonography).
Material and methods: This is a retrospective study of consecutive patients diagnosed with DCIS after percutaneous biopsy. We estimated Lin's coefficient of concordance for the histologic findings with each of the three techniques. We also assessed concordance using Bland-Altman graphs. Finally, we determined the impact of the MRI findings on the surgical management of patients with DCIS.
Results: A total of 32 patients were included in the study. Concordance between imaging and histology on tumor size was higher for MRI (0.78; 95%CI, 0.62-0.87) than for mammography (0.43; 95%CI, 0.19-0.62) or for ultrasonography (0.27; 95%CI, 0.09-0.43). MRI overestimated the size of DCIS by a mean of 3 mm, whereas mammography and ultrasonography underestimated it by 9 mm and 18 mm, respectively. MRI detected multifocality and multicentricity (7 cases) better than mammography (3) or ultrasonography (0). The MRI findings correctly changed the surgical management in six patients.
Conclusion: Breast MRI is better than conventional techniques for the evaluation of the size of DCIS. Breast MRI also detects more cases of multifocality and multicentricity. We recommend that all patients diagnosed with DCIS (especially those with dense breasts) undergo breast MRI prior to surgery.