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Perfect Registration Leads to Imperfect Performance

A Randomized Trial of Multimodal Intraoperative Image Guidance

Dilley, James W. R., MRCOG; Hughes-Hallett, Archie, PhD; Pratt, Philip J., PhD; Pucher, Philip H., PhD; Camara, Mafalda, MSc; Darzi, Ara W., FRS; Mayer, Erik K., PhD

doi: 10.1097/SLA.0000000000002793

Objective: To compare surgical safety and efficiency of 2 image guidance modalities, perfect augmented reality (AR) and side-by-side unregistered image guidance (IG), against a no guidance control (NG), when performing a simulated laparoscopic cholecystectomy (LC).

Background: Image guidance using AR offers the potential to improve understanding of subsurface anatomy, with positive ramifications for surgical safety and efficiency. No intra-abdominal study has demonstrated any advantage for the technology. Perfect AR cannot be provided in the operative setting in a patient; however, it can be generated in the simulated setting.

Methods: Thirty-six experienced surgeons performed a baseline LC using the LapMentor simulator before randomization to 1 of 3 study arms: AR, IG, or NG. Each performed 3 further LC. Safety and efficiency-related simulator metrics, and task workload (SURG-TLX) were collected.

Results: The IG group had a shorter total instrument path length and fewer movements than NG and AR groups. Both IG and NG took a significantly shorter time than AR to complete dissection of Calot triangle. Use of IG and AR resulted in significantly fewer perforations and serious complications than the NG group. IG had significantly fewer perforations and serious complications than the AR group. Compared with IG, AR guidance was found to be significantly more distracting.

Conclusion: Side-by-side unregistered image guidance (IG) improved safety and surgical efficiency in a simulated setting when compared with AR or NG. IG provides a more tangible opportunity for integrating image guidance into existing surgical workflow as well as delivering the safety and efficiency benefits desired.

Department of Surgery and Cancer, Imperial College London, London, UK.

Reprints: Erik K. Mayer, PhD, Department of Surgery and Cancer, Imperial College London, St Mary's Hospital Campus, 10th Floor, QEQM Building, Praed Street, London W2 1NY, UK. E-mail:

This study is independent research funded by the National Institute for Health Research Imperial Biomedical Research Centre. The views expressed in this publication are those of the author(s) and not necessarily those of the NHS, the National Institute for Health Research or the Department of Health.

The authors report no conflicts of interest.

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