Gadopentetate dimeglumine-enhanced chemical-shift MR imaging of the breast

Standard T1-weighted MR images enhanced with gadopentetate dimeglumine show relatively minimal enhancement of breast lesions due to the high background signal from fat in the breast. Strongly enhancing lesions may become isointense relative to the fat signal and become invisible or indistinct after contrast administration. Fat-suppressed chemical-shift imaging (CSI) combined with administration of gadopentetate dimeglumine improves lesion detection and characterization in other areas of the body where a strong lipid signal is present. We evaluated this technique in the breast. Twenty patients with mammographic lesions were studied with standard unenhanced T1- and T2-weighted images and enhanced T1-weighted images, as well as with CSI before and after administration of gadopentetate dimeglumine. The series were ranked independently for border and matrix characteristics. The border was assessed for a smooth, irregular, or spiculated margin. The matrix or internal substance was evaluated for visibility and type of enhancement, homogeneous or inhomogeneous. The enhanced CSI images were superior to all other images in the depiction of border and matrix characteristics. Of 20 patients, a corresponding mass was detected on MR in 14. In two of the 14 patients, the lesion was seen only in the enhanced CSI images. Chemical-shift artifacts on enhanced T1-weighted images obscured border detail in several cases. Enhanced CSI improves visualization of breast lesions as compared with conventional MR imaging with or without enhancement. The enhanced CSI technique produces differential enhancement between glandular tissue and lesions while suppressing the signal from fat. This improves the visualization of border and matrix characteristics and depicts lesions that otherwise might be obscured.