[MR subtraction in the differentiation of benign and malignant tumors]

To evaluate dynamic contrast-enhanced MRI in conjunction with MR subtraction in the differential diagnosis of benign and malignant breast tumors at 3 Tesla.

A total of 78 patients with breast tumors enrolled in this study, including 45 malignant lesions and 33 benign lesions verified by histopathology. Dynamic MR contrast enhanced imaging was done by T1 high resolution isotropic volume excitation sequence. MR subtraction was used to retrospectively analyze the MR dynamic image. A dynamic phase subtraction (DPS) map is a map image with pixel-by-pixel subtraction of an early-phase image from a delayed maximum enhancement phase image obtained in a dynamic study. The sensitivity and specificity were calculated with or without subtraction in the diagnosis of benign and malignant breast tumors.

The sensitivity of benign breast masses increased from 0.879 to 0.939, and the specificity increased from 0.818 to 0.909 with reference to the DPS map. There was statistical difference between with or without DPS (Z=2.023, P=0.043). The sensitivity of breast malignant masses increased from 0.889 to 0.933, and the specificity increased from 0.867 to 0.911 with reference to the DPS map, with statistical difference between with or without DPS map (Z=2.294, P=0.021). The pattern of TIC changed from continuous to a plateau in 8 patients, from a plateau to washout in 10, and from continuous to washout in 5. No changes were observed in the other 55 patients.

MR Subtraction is a simple and useful technique to identify breast lesions. It helps to accurately set the location of the ROI TIC and improve the detection rate of benign and malignant breast tumors.