Kuhl CK et al. (2007) MRI for diagnosis of pure ductal carcinoma in situ: a prospective observational study. Lancet 370: 485–492

MRI has traditionally been regarded as an inferior technique for the detection of ductal carcinoma in situ (DCIS) because of its failure to detect all cancers that are apparent on mammography. Recently, however, it has been reported that MRI might enable the prospective diagnosis of DCIS that is undetectable on mammography. Now, Kuhl et al. have investigated the relative diagnostic sensitivities of MRI and mammography for DCIS, and suggest that the former technique better identifies high-grade DCIS, which is more likely than low-grade DCIS to progress to high-grade invasive breast cancer.

In total, 7,319 women underwent breast MRI and mammography at a German tertiary referral center during the 5-year study period. A positive imaging result was found in 1,208 cases, with final surgical diagnoses of invasive breast cancer and pure DCIS made in 469 and 167 women, respectively. Significantly more cases of confirmed DCIS were detected by MRI than on mammography (92% vs 56%; P <0.0001). DCIS was detected by both imaging techniques in 81 (49%) cases, by mammography only in 12 (7%) cases, and by MRI only in 72 (43%) cases. Notably, MRI demonstrated high sensitivity for high-grade DCIS, detecting 98% of these lesions. By contrast, only 52% of high-grade DCIS was identified on mammography.

The authors conclude that mammography might often fail to detect pure DCIS, especially high-grade cancers. MRI might be useful in the diagnosis of these lesions, which are likely to progress to invasive breast cancer.