Impact of real-time virtual sonography, a coordinated sonography and MRI system that uses an image fusion technique, on the sonographic evaluation of MRI-detected lesions of the breast in second-look sonography.

ABSTRACT

The aim of this study was to verify the utility of second-look sonography using real-time virtual sonography (RVS)-a coordinated sonography with an MRI system that uses an image fusion technique with magnetic navigation-on the sonographic evaluation of MRI-detected lesions of the breast. Of the 196 consecutive patients who were examined with breast MRI in our hospital from 2006 to 2009, those patients who underwent second-look sonography to identify MRI-detected lesions were enrolled in this study. MRI was performed using a 1.5-T imager with the patient in a supine position. To assess the efficacy benefits of RVS, the correlations between lesion detection rates, MRI features, distribution, and histopathological classification on second-look sonography using conventional B-mode or RVS were analyzed. Of the 196 patients, 55 (28 %) demonstrated 67 lesions initially detected by MRI, followed by second-look sonography. Of the 67 MRI-detected lesions, 18 (30 %) were identified with second-look sonography using conventional B-mode alone, whereas 60 (90 %) lesions were detected with second-look sonography using RVS (p < 0.001). The detection rates of 16 focal lesions, 46 mass lesions, 16 lesions sized <5 mm, 45 lesions sized 5-10 mm, 26 lesions situated within the mammary gland, 41 lesions situated around mammary fascia, 24 malignant lesions, and 43 benign lesions were, respectively, 25, 26, 25, 24, 42, 17, 33, and 23 % by conventional B-mode, and were significantly higher, respectively, at 94, 89, 94, 89, 88, 90, 92, and 88 % by RVS. Of the seven lesions with no sonographic correlates, five could be biopsied by marking MRI information onto the body surface using RVS. Overall, 65 of 67 (97 %) MRI-detected lesions were confirmed by histopathological results. Our results suggest that the additional use of RVS on second-look sonography significantly increases the sonographic detection rate of MRI-detected lesions without operator dependence.