OBJECTIVETo explore the differences between the angioarchitecture, hemodynamics, ultrastructure of neovasculr endothelial cells, and vascular distribution in different perfusion regions in benign and malignant breast tumors.

METHODS30 cases of breast carcinoma (33 lesions) and 30 cases of breast fibroadenoma (34 lesions) were examined by contrast enhanced microvascular imaging (MVI), and perfusion indexes were collected both inside and at the margin of each focus according to time-intensity quantitative analysis, including peak intensity (PI), area under the curve (AUC), time to peak (TTP) and wash-out time (WOT). The ultrastructure of neovascular endothelial cells was examined by transmission electron microscopy. The expression of CD34, VEGF, Flk-1/KDR in both two groups were detected by immuhistochemistry.

RESULTSSignificant differences were found between the two groups characterized with filling defect, vascular distortion, dilatation and uneven enhancement. Most of the curves of malignant group (87.9%, 29/33) ascended rapidly and dropped slowly while those of the benign group (79.4%, 27/34) ascended slowly and dropped rapidly. The AUC and WOT of malignant tumor group were significantly higher than those of benign group, while the PI and TTP had statistically no significant difference. In the malignant tumor group, PI, AUC and WOT collected from the margin of foci were significantly different from those collected inside the foci, however, there was no significant difference in the benign group. The margin of foci was characterized with dilated and distorted vessels, and the center of the foci was occupied by narrow or occluded blood vessels, sometimes with contracted endothelial cells and pericytes. Abundant microvascular areas located at the margin of foci. The ultrastructure of endothelial cells in the newly formed blood vessels of malignant group showed strong ability to divide, which was different from normal endothelium cells.

CONCLUSIONThe perfusion pattern, mode of time-intensity curve, mean perfusion parameter and variation of regional perfusion parameters provide a valuable diagnostic basis in distinguishing benign and malignant breast tumors. The density, morphology, distribution, structure and function of newly formed microvessels in tumor foci are also crucial factors when tumors are assessed by imaging examination.