Cone beam computed tomography for percutaneous nephrolithotomy: initial evaluation of a new technology.

BACKGROUND AND PURPOSE

Cone beam CT (CBCT) is a novel imaging modality that combines the versatility of conventional C-arm imaging with the functionality of cross-sectional imaging. This is a pilot study to evaluate the capabilities of this new technology to obtain percutaneous access and for the immediate postoperative evaluation of residual fragments in percutaneous nephrolithotomy (PCNL).

MATERIALS AND METHODS

A retrospective analysis of all PCNL cases performed between April 2007 and November 2007 was performed. One urologist (NSS) and one radiologist (JFA) reviewed the studies postoperatively. Preoperative films were evaluated to see if CBCT influenced or improved percutaneous access. Postoperative films were evaluated that compared CBCT with conventional noncontrast CT to determine efficacy in finding postoperative stone fragments. Parameters of stone size, location, and quantity of fragments were compared.

RESULTS

For preoperative access, CBCT was used in 52 cases of PCNL between April 2007 and November 2007. In eight of these cases, CBCT altered the percutaneous access. In postoperative evaluation, 26 cases had both CBCT and conventional CT for comparison. In 11 cases with residual stones, conventional CT identified a greater number of fragments, but these were less than 2 mm. The postoperative recommendation for a secondary procedure concurred in 22 of 26 studies.

CONCLUSIONS

CBCT may provide advantages of improved preoperative imaging, which may result in better percutaneous access, and improved postoperative imaging, which allows surgeons to have "real-time" access to CT quality images. The intraoperative availability of these high quality tomographic images may obviate the need for other postoperative imaging and subsequent adjunctive procedures for residual fragments.