Introduction- Ultrasound is the most difficult imaging modality to master. The generation of the images are operator dependent and therefore effective and safe use of ultrasound to guide surgical procedures requires experience. In this paper the authors will describe a 3D ultrasound system for use during cryosurgical procedures that has the potential to simplify the learning curve associated with ultrasound guided cryosurgery.
Method- The 3D ultrasound system consists of a Macintosh Power PC computer which has the dual function of controlling a motor connected to the bi-plane transrectal ultrasound probe and collecting the 2D ultrasound data and reconstructing the 3D ultrasound model. The computer turns the US probe at a known rate while multiple images are captured from the video output of the ultrasound machine which it then reconstructs into the 3D data set. The data set can then be viewed in all planes. The system was tested during prostate cryosurgery procedures on 21 patients, in addition animal work on liver cryosurgery was also carried out.
Results- Reconstruction time for a 3D data set is now less than 10 seconds, well within the range of clinical usefulness. The system was used in 21 prostate cryosurgery cases and in all 21 cases the coronal view of the 3D ultrasound data revealed at least one poorly placed probe.
Conclusion- The use of 3D ultrasound can improve the accuracy of prostate cryosurgery and presumably other ultrasound guided cryosurgery procedures by demonstrating the orientation of misplaced probes in the coronal view, which is not available otherwise. Integration of guidance systems into the 3D ultrasound program could help improve probe placements prospectively.