Direct MRI-guided biopsy of the prostate: use of post-biopsy needle track imaging to confirm targeting

Purpose: To report the observation that in-plane post-biopsy T2-weighted MRI often demonstrates the needle track as a transient visible linear tissue distortion during direct MRI-guided biopsy. Materials and methods: We retrospectively identified 11 prostatic lesions in 9 men that underwent direct MRI-guided biopsy and in which post-biopsy images were obtained in the plane of the biopsy needle. Results: In 9 of 11 targets, a post-biopsy needle track was visible as a linear tissue distortion on in-plane T2-weighted images obtained at a mean interval of 6 min (range 3–15). In these nine cases, the needle track traversed the intended target, and the biopsy was positive for malignancy in six. Biopsy was positive in one of two cases where the needle track was not visible. In five targets, one or more delayed series were obtained after a mean interval of 21 min (range 8–33), showing the track was no longer visible (n = 3) or was of progressively decreased conspicuity (n = 2). Conclusion: Accurate targeting during direct MRI-guided biopsy of the prostate can be confirmed by obtaining post-biopsy in-plane images, since the needle track is usually visible as a transient linear tissue distortion.