Objective: The purpose of this study was to assess the usefulness of numeric ratios from dynamic contrast-enhanced MRI in predicting histologic type of breast carcinoma and three histologic prognostic factors for invasive ductal carcinoma.
Materials and methods: A total of 104 patients with breast carcinoma were included in the study. Dynamic contrast-enhanced MR images were obtained every 30 seconds during the first 4.5 minutes after administration of contrast material, and peripheral contrast enhancement ratio and central contrast enhancement ratio were calculated in the early phase (1 minute after contract injection) and in the delayed phase (4 minutes after injection). Four contrast enhancement ratios were used for quantitative analysis of the following numeric ratios: early peripheral/early central, delayed peripheral/delayed central, delayed peripheral/early peripheral, and delayed central/early central. The four ratios were compared with histologic type. For invasive ductal carcinoma, the ratios were then compared with modified Scarff-Bloom-Richardson histologic grade, microvessel density, and fibrotic focus.
Results: Mucinous carcinoma had significantly higher mean early peripheral/early central and delayed central/early central ratios than other types of tumors (p< 0.0001). For invasive ductal carcinoma, the mean early peripheral/early central ratio was significantly lower for modified Scarff-Bloom-Richardson grade 1 tumors than for grades 2 and 3 tumors (p < 0.0001). Early peripheral/early central ratio had a significant correlation with the ratio of peripheral to central mean microvessel density (p < 0.0001). There was also a significant difference in early peripheral/early central ratio (p < 0.0001) between tumors with a fibrotic focus and those without a fibrotic focus.
Conclusion: Numeric ratios obtained on gadolinium-enhanced dynamic MRI of the breast may be useful in predicting histologic type of breast carcinoma and three histologic prognostic factors for invasive ductal carcinoma: modified Scarff-Bloom-Richardson grade, microvessel density, and fibrotic focus.