Objective: To assess the value of four-dimensional ultrasonography (dynamic three-dimensional ultrasonography with the added dimension of time) in ultrasonographically guided biopsy procedures of focal hepatic masses.
Methods: Four-dimensional ultrasonographically guided biopsy experiments using a freehand technique were performed in phantoms that simulated human liver tissue and had target material. After the protocol was determined and Institutional Review Board approval was obtained, 12 patients underwent four-dimensional ultrasonographically guided biopsy of focal hepatic masses by informed consent. Planar images using 3 orthogonal planes plus a volume-rendered image were used for real-time guidance during the biopsy procedure.
Results: Four-dimensional ultrasonography improved visualization of biopsy devices in all 12 patients (100%) regardless of minor changes in transducer position during the biopsy procedures. Four-dimensional ultrasonography allowed more intuitive apprehension of the spatial relationship of the needle and the target lesion and thus helped in adjusting the needle to an optimal prefiring position in 8 patients (67%). With regard to procedure time, four-dimensional ultrasonographically guided biopsy was comparable with standard two-dimensional ultrasonographically guided techniques.
Conclusions: Compared with standard two-dimensional ultrasonographically guided biopsy, four-dimensional ultrasonography provides improved visualization of biopsy devices and more perceptible information on the spatial relationship between the biopsy needle and the target lesion.