Breast Lesions: Correlation of Dynamic Contrast Enhancement Patterns on MR images with Tumor Angiogenesis

OBJECTIVE To determine whether dynamic contrast-enhanced MRI features of the early-phase enhancement rate, enhancement amplitude, and signal-intensity (SI) time course are associated with the microvessel density (MVD) and vascular endothelial growth factor (VEGF) expression of malignant and benign breast lesions.

METHODS Sixty patients with breast lesions, detected with physical examination or conventional mammography, were examined preoperatively with dynamic contrast-enhanced MRI from December 1998 to June 2000. Of these 60 patients, histopathological correlation was available in 38. These 38 patients(aged 29-73 years) formed the basis of this study. SI changes during dynamic scanning were assessed quantitatively. Early-phase enhancement rate and enhancement amplitude were calculated. Time-SI curves of the lesions were obtained and classified according to their shapes as type I (which was steady enhancement to the end of the dynamic data acquisition at 7.5min.), type II (plateau of SI after avid Initial contrast enhancement), or type III (washout of SI after avid initial contrast enhancement). The mean MVD and VEGF expression of the lesions were measured with immunohistochemical staining methods in all the pathologic specimens by a pathologist without knowledge of the results of the MR examination. Care was taken to ensure identical location In the plane of the MR Image and pathologic specimens. The relationships among dynamic contrast-enhanced MRI features, MVD, and VEGF expression of benign and malignant breast lesions were analyzed.

RESULTS Histology revealed 21 malignancies and 17 benign lesions. The mean MVD and VEGF expression for the 21 malignant lesions were significantly higher than the mean MVD and VEGF expression for the 17 benign lesions (P<0.01). High VEGF expression of benign and malignant breast lesions showed a significant association with Increased MVD (P< 0.01). Among all 38 lesions, greater (>60%) MR early-phase enhancement rate and time-SI curve type II or III showed a significant association with MVD and VEGF expression. All the differences mentioned above showed statistical significance (P <0.01) except the difference between VEGF expression and the distribution of curve types which had no statistical significance (P=0.069). No significant relationships were observed between the enhancement amplitude and MVD (P>0.05) and VEGF expression (P> 0.05). Regarding the distribution of MVD, the study showed that the greater MVD was most frequently observed at the marginal region of the breast cancers, although the distribution of MVD was heterogeneous in each lesion.

CONCLUSIONS MVD and VEGF affect the contrast medium enhancement of breast lesions. The early-phase enhancement rate and time-SI curve types of benign and malignant breast lesions are closely related to MVD and VEGF. As a noninvasive method, contrast-enhanced MRI has a potential role In estimating the degree of angiogenesis of breast neoplasms.