Ghost imaging for targeting breast masses with MR imaging: a phantom study

RATIONALE AND OBJECTIVES: The purpose of this study was to test the accuracy of ghost magnetic resonance (MR) imaging for guiding core biopsies of simulated breast masses in a tissue phantom. MATERIALS AND METHODS: A tissue MR phantom implanted with 20 grapes as targets was placed into an interventional breast MR coil. The locations of the centers of the targets were determined, recorded, and saved as ghost images. A nonmagnetic phantom needle was constructed to avoid imprecision secondary to magnetic field inhomogeneity and was used to determine the three-dimensional location of the needle tip in the center of each grape on the ghost image. Once the positions were determined, the true needle was placed and biopsy specimens were taken. The needle was inspected for the presence of pulp after each pass. Each grape was inspected to determine the location of the needle track in relation to the center of the grape. The duration of the procedure was recorded. RESULTS: All grapes were hit by the biopsy needle, as demonstrated either by pulp within the needle or by a needle track within the grape. Seventeen of the 20 grapes (85%) were hit centrally. Three were sampled eccentrically, up to 5-6 mm from the center. Each biopsy took approximately 1 hour. CONCLUSION: These results suggest that ghost imaging may be ideal for needle guidance in core biopsy or preoperative localization, as it extends the period of visibility after a bolus injection of contrast material. Additionally, using a phantom needle for localization appears to overcome imprecision due to magnetic field inhomogeneity of the needle.