Figure 2a. MR imaging-guided 14-gauge core biopsy of the left breast in a 49-year-old high-risk patient with a familial history suggestive of breast cancer. A 6-mm lesion with suggestive enhancement had been detected at screening breast MR imaging (screening image not shown). MR imaging-guided core biopsy revealed a 6-mm focus of adenosis and epitheliosis without atypia. Because, owing to the vanishing target, the lesion was invisible during intervention, and because radiologic-pathologic mismatch could not be excluded, secondary excisional biopsy was performed after MR imaging-guided hook wire placement. Excisional biopsy findings confirmed the core biopsy diagnosis of focal adenosis without atypia. Follow-up was 8 months. (a) Transverse precontrast T1-weighted gradient-echo image (280/4.6; flip angle, 90°) from the dynamic series obtained prior to biopsy. As in Figure 1a, the breast is immobilized in the mediolateral direction by the two compression plates. The white dots (arrowheads) medial and lateral to the breast are part of the stereotactic unit’s fiducial system. (b) Transverse postcontrast T1-weighted gradient-echo image with acquisition parameters equivalent to those in a shows a 6-mm enhancing target lesion (arrowheads). (c) Transverse postcontrast T1-weighted gradient-echo image with acquisition parameters equivalent to those in a and b, obtained after administration of local anesthetic and placement of the needle phantom (arrowheads) to simulate the calculated needle trajectory, shows the lesion as only faintly visible with reversed contrast (vanishing target) because of progressive contrast enhancement in the adjacent parenchyma combined with a rapid washout of contrast material in the lesion. (d) Transverse T2-weighted turbo SE image (3,000/120) obtained after introduction of the 14-gauge core biopsy needle shows that the target at the calculated stereotactic coordinates (arrowheads) is not visible. No tissue shift is induced with the needle. (e) Transverse T2-weighted turbo SE image (3,000/120) obtained after firing the biopsy gun shows that the needle has passed exactly through the calculated position of the target (arrowheads) and that the target itself is not visible.