Accuracy of sonographically guided biopsy using a freehand versus needle-guided technique: computed tomographic correlation study.

Sonographically guided biopsy is performed by one of two techniques: the freehand and needle-guided techniques. To our knowledge, the relationship between the location of the local anesthetic tract and the biopsy needle tract as well as direct comparison of the two biopsy techniques has not been previously validated. The aim of this study was to validate the different parameters related to the two biopsy techniques using computed tomography as the reference standard for assessing final tract positions. There were statistically significant differences between the freehand and guided techniques in the following parameters: number of passes required for contrast agent injection (P = .003), number of passes required to insert the needle (P = .005), time required to inject the anesthetic/contrast agent (P = .005), time required to insert the biopsy needle (P = .02), and distance between contrast tract and final needle position (P = .03). No statistical difference was identified for the angle between the contrast tract and needle position. This difference likely reflects the confidence of the radiologist in identifying the needle location during the procedure. Using a commercially available guide that has a fixed angle can result in a faster, more efficient, and reproducible biopsy technique compared to the freehand technique, especially for those who have less experience in performing sonographically guided biopsies.