To compare the contrast-enhanced dynamic MR findings of solid breast masses with their histopathologic tumor angiogenesis.

Thirty-two cases of pathologically proved breast lesions (8 benign and 24 malignant lesions) examined with contrast-enhanced MRI were retrospectively reviewed, focusing on the tumor size, the maximum amount of contrast enhancement (% Signal Intensity Change, SIC), the time to peak (early or late peak) and the type of time-signal intensity curve (TSC). We compared the characteristic MR findings of breast cancer with the microscopic maximum microvessel density (MVD).

Among the total of 11 small lesions (≤2 cm, 9 malignant and 2 benign), 8 cases of malignant lesions showed high MVD (≥20). On the other hand, among the 21 large lesions (> 2 cm, 15 malignant and 6 benign), only two cases of malignant and five cases of benign lesions showed high MVD. More than 100% SIC was observed in a total of 11 malignant and two benign lesions, but 8 of these 11 malignant lesions showed low MVD (< 20), whereas the two benign lesions showed high MVD. Early time to peak (≤3 min) was observed in 18 (17 malignant and 1 benign) lesions, and 11 of these 17 malignant lesions showed low MVD. An early high peak and early or slow wash-out pattern, which is typical of the malignant type, was seen in 18 (17 malignant and 1 benign) lesions, but 12 of these 17 malignant lesions showed low MVD. There is no statistically significant correlation between the characteristic MR findings of breast cancer and the MVD.

Although high MVD indicated malignancy in the case of the small lesions, the histopathologic MVD was not significantly correlated with either the increased amount of enhancement, early time-to peak or the malignant pattern of the TSC.