Mairead Smith, Project Engineer. ECRI Institute
Objective of the Technology
Three-dimensional (3D) surgical video systems (SVS) are intended to improve the surgeon’s ability to perceive depth during laparoscopic procedures.
ECRI Institute’s evaluation seeks to determine what benefits are offered by 3D SVS, particularly as compared to two-dimensional (2D), high definition (HD) SVS, and to assess whether the benefits are worth the additional cost of upgrading to 3D.
Description of the Technology
3D SVS create the appearance of depth by replicating binocular vision – they use two adjacent cameras to capture two video streams from the tip of a single laparoscope. The video streams are then transmitted to a 3D-compatible display. Viewers wear polarized glasses so that each eye sees one video stream.
Currently available 3D SVS can be switched between 2D and 3D modes as needed.
We evaluated two 3D SVS: Olympus EndoEye Flex 3D and Karl Storz Image 1 S 3D. Our evaluation considered several metrics of video quality, including spatial resolution, contrast-to-noise ratios, and depth of field. We also developed test methods to quantify improvement in depth perception as compared to 2D HD SVS. These tests included:
Pin order identification (Figure 1) – surgeons indicated which pins in an array were closer than others.The separation distance between pins varied, and the success rate was calculated at each distance.
Figure 1: Array of four pins.
Needle angle perception (Figure 2) – surgeons indicated whether a curved suture needle pointed towards them or away.The overall success rate was determined.
Figure 2: Needle direction test
Stapler alignment perception (Figure 3) – surgeons aligned and connected the anvil to a circular stapler. We recorded the time required and the number of errors.
Figure 3: Alignment of circular stapler and anvil
Due to the spatial constraints of fitting two camera chips on a laparoscope, we found that the video quality of 3D SVS was good, but slightly lower than that of 2D HD SVS:
Limiting spatial resolution was comparable to 2D HD systems, at 5-8 cycles/degree
Contrast-to-noise ratios were adequate, but were dependent on light levels and varied between systems
Grayscale ratios were comparable to 2D, in the range of 5-19.
Color contrast ratios for 2D systems are commonly 12-18.For Storz they were lower, reaching 7.8.For Olympus, they were high, over 21.5.
Depth of field was adequate for both systems, at about 1.75 inches, though slightly lower than 2D systems (typically about 2 inches).Both 3D videoscopes autofocused to adjust to changing laparoscope positions
Conclusions and Future Directions
We plan to conduct tests of depth perception with surgeons at the end of January 2017. Our results will compare 2D with 3D depth perception, and will offer an unbiased assessment of the benefits of 3D SVS.
Since 3D SVS require new videoscopes, displays, and camera control units, they tend to cost about 65% more than the average 2D HD SVS. Facilities considering upgrading to 3D will need to consider whether it is worth the additional cost.
Presented at the SAGES 2017 Annual Meeting in Houston, TX.
Abstract ID: 84425
Program Number: ETP726
Presentation Session: Emerging Technology Poster
Presentation Type: Poster