A projector-based augmented reality intracorporeal system (PARIS) is presented that includes a miniature tracked projector, tracked marker, and laparoscopic ultrasound (LUS) transducer. PARIS was developed to improve the efficacy and safety of laparoscopic partial nephrectomy (LPN). In particular, it has been demonstrated to effectively assist in the identification of tumor boundaries during surgery and to improve the surgeon’s understanding of the underlying anatomy. PARIS achieves this by displaying the orthographic projection of the cancerous tumor on the kidney’s surface. The performance of PARIS was evaluated in a user study with two surgeons who performed 32 simulated robot-assisted partial nephrectomies. They performed 16 simulated partial nephrectomies with PARIS for guidance and 16 simulated partial nephrectomies with only an LUS transducer for guidance. With PARIS, there was a significant reduction [30% (p<0.05)] in the amount of healthy tissue excised and a trend toward a more accurate dissection around the tumor and more negative margins. The combined point tracking and reprojection root-mean-square error of PARIS was 0.8 mm. PARIS’ proven ability to improve key metrics of LPN surgery and qualitative feedback from surgeons about PARIS supports the hypothesis that it is an effective surgical navigation tool.
Purpose: To compare the accuracy of detecting tumor location and size in the prostate using both manual palpation and
ultrasound elastography (UE). Methods: Tumors in the prostate were simulated using both synthetic and ex vivo tissue
phantoms. 25 participants were asked to provide the presence, size and depth of these simulated lesions using manual
palpation and UE. Ultrasound images were captured using a laparoscopic ultrasound probe, fitted with a Gore-Tetrad
transducer with frequency of 7.5 MHz and a RF capture depth of 4-5 cm. A MATLAB GUI application was employed to
process the RF data for ex vivo phantoms, and to generate UE images using a cross-correlation algorithm. Ultrasonix
software was used to provide real time elastography during laparoscopic palpation of the synthetic phantoms. Statistical
analyses were performed based on a two-tailed, student t-test with α = 0.05. Results: UE displays both a higher accuracy
and specificity in tumor detection (sensitivity = 84%, specificity = 74%). Tumor diameters and depths are better
estimated using ultrasound elastography when compared with manual palpation. Conclusions: Our results indicate that
UE has strong potential in assisting surgeons to intra-operatively evaluate the tumor depth and size. We have also
demonstrated that ultrasound elastography can be implemented in a laparoscopic environment, in which manual
palpation would not be feasible. With further work, this application can provide accurate and clinically relevant
information for surgeons during prostate resection.