Introduction: Breast imaging modalities can assess the tumor extent and adequacy of excision, but there have been no reports comparing magnetic resonance (MR) imaging, multidetector row computed tomography (MDCT), ultrasonography (US) and mammography (MMG) for the tumor extent of breast cancer. We prospectively assessed the accuracy of MR imaging, MDCT, US and MMG for preoperative assessment of the tumor extent of breast cancer.
Methods: Preoperative MR imaging, MDCT, US and MMG were performed for 210 breasts with breast cancer. The MR and MDCT images were independently interpreted by one of two radiologists with knowledge of the clinical and MMG findings. The US was performed with knowledge of the clinical and MMG findings by one of five US technologists. The correlation of the results of these examinations with histological findings was examined.
Results: Of the 210 index breast tumors, 210 (100%) could be detected on MR, 208 (99%) were detected on MDCT, 209 (99.5%) were detected on US, and 195 (93%) were detected on MMG. For evaluating local tumor extent, the accuracy of MR imaging (76%) was significantly higher than those of MDCT, US, and MMG (71%, 56%, and 52%, respectively) (P = 0.001, P < 0.0001, and P < 0.0001). MDCT was significantly more accurate than US (P < .0001) or MMG (P < .0001), and US was significantly more accurate than MMG (P = 0.004). MR imaging and US had substantial risk (11% and 17%) of overestimation of the tumor extent. Regarding ductal carcinoma in situ (DCIS), for non-comedo DCIS, the accuracies of MR imaging (89%), MDCT (72%), and US (61%) were significantly higher than the 22% accuracy of MMG (P < 0.0001, P = 0.012, and P = 0.016), but for comedo DCIS, there were no significant differences among the four breast imaging modalities.
Conclusion: MR imaging was the most accurate breast imaging modality for the tumor exten of breast cancer, although MR imaging had a substantial of risk of overestimation. MR imaging, MDCT and US can complement MMG for the preoperative evaluation of patients who are candidates for breast-conserving surgery.