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

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.