Correlation between enhancement characteristics of MR mammography and capillary density of breast lesions

To correlate capillary density of breast lesions using the markers D2-40, CD31, and CD34 with early and late enhancement of magnetic resonance mammography (MRM).

The local ethics committee approved this study, and informed consent was avail-able from all patients. The study included 64 women with 66 histologically proven breast lesions (41 malignant, 25 benign). MR-enhancement 1 min after contrast medium administration was determined in the tumor (It1/It0 ratio) and in comparison to the surrounding tissue (It1/It1-fat ratio). Capillary density was quantified based on immunohistological staining with D2-40, CD31, and CD34 in breast tumors and surrounding breast tissue. Mean capillary densities were correlated with contrast enhancement in the tumor and surrounding breast tissue. The Kruskal-Wallis test was used to test whether lesions with different MR enhancement patterns differed in terms of capillary density.

For CD34, there was statistically significant correlation between capillary density and tumor enhancement (r = 0.329, p = 0.012), however not for the malignant or benign groups separately. Mean vessel number identified by staining with D2-40 and CD31 did not correlate significantly with tumor enhancement (D2-40: r = -0.188, p = 0.130; CD31: r = 0.095, p = 0.448). There were no statistically significant differences in capillary density between breast lesions with delayed enhancement or a plateau and lesions showing washout (Kruskal-Wallis test. D2-40: p = 0.173; CD31: p = 0.647; CD34: p = 0.515).

Of the three markers tested, CD34 showed best correlation between early contrast enhancement on MRM and capillary density. Further studies are necessary to clearly demonstrate an association between capillary density and contrast enhancement in breast tumors and surrounding tissue.