@article {Yeo2017, title = {3D Segmentation as a Surgical Planning Tool for Residents in Liver Resection Surgery}, year = {In Press}, abstract = {

Introduction: Liver surgery requires identification of tumor(s) in relation to key vessels to preserve healthy tissue, while obtaining negative margins. Current planning is mentally strenuous for residents as it relies on mental 3D reconstruction, anatomical knowledge, spatial sense, and experience. The purpose of this study is to determine if 3D segmentation improves resident ability to devise appropriate liver resection plans.

Methods: Senior general surgery residents were recruited. Pre-operative CT/MR images were selected if they reflected actual surgeries performed. Images were segmented to create interactive 3D models. Residents were asked to devise surgical plans for case-matched 2D and 3D models in an alternating, randomly generated order. Primary outcome was correct preoperative plan based on actual surgery performed. Secondary outcome was time (seconds(s)) to devise plan. Planning data was analyzed using Wilcoxon test, time was analyzed using paired t-test.

Results: All 14 senior residents from our institution participated. The average correct response was 1.7 of 5 (34\%; range 1 to 4) for the 2D group, and 3.1 of 5 (62\%; range 0 to 4) for the 3D group (p\<0.01). The average time to complete each plan was 156{\textpm}107s for the 2D group, and 84{\textpm}73s for the 3D group (p\<0.01).

Conclusions: The results show that 3D segmentation increases accuracy of surgical planning and decreases amount of time required. 3D segmentation is useful as a teaching tool as it reduces cognitive load required to mentally reconstruct 2D images, allowing the resident to focus on surgical planning. It improves understanding of spatial liver anatomy and serves as an adjunct to current 2D planning methods. This has the potential to be developed into a module for teaching liver surgery relevant to a competency-based curriculum.

}, author = {Yeo, Caitlin T and MacDonald, Andrew and Tamas Ungi and Andras Lasso and Diederick Jalink and Gabor Fichtinger and Nanji, Sulaiman} } @article {Yeo2017, title = {Utility of 3D Reconstruction of 2D Liver Computed Tomography/Magnetic Resonance Images as a Surgical Planning Tool for Residents in Liver Resection Surgery}, journal = {Journal of Surgical Education}, volume = {75}, number = {3}, year = {2018}, month = {08/2017}, pages = {792-797}, abstract = {

Objective

A fundamental aspect of surgical planning in liver resections is the identification of key vessel tributaries to preserve healthy liver tissue while fully resecting the tumor(s). Current surgical planning relies primarily on the surgeon{\textquoteright}s ability to mentally reconstruct 2D computed tomography/magnetic resonance (CT/MR) images into 3D and plan resection margins. This creates significant cognitive load, especially for trainees, as it relies on image interpretation, anatomical and surgical knowledge, experience, and spatial sense. The purpose of this study is to determine if 3D reconstruction of preoperative CT/MR images will assist resident-level trainees in making appropriate operative plans for liver resection surgery.

Design

Ten preoperative patient CT/MR images were selected. Images were case-matched, 5 to 2D planning and 5 to 3D planning. Images from the 3D group were segmented to create interactive digital models that the resident can manipulate to view the tumor(s) in relation to landmark hepatic structures. Residents were asked to evaluate the images and devise a surgical resection plan for each image. The resident alternated between 2D and 3D planning, in a randomly generated order. The primary outcome was the accuracy of resident{\textquoteright}s plan compared to expert opinion. Time to devise each surgical plan was the secondary outcome. Residents completed a prestudy and poststudy questionnaire regarding their experience with liver surgery and the 3D planning software.

Setting and Participants

Senior level surgical residents from the Queen{\textquoteright}s University General Surgery residency program were recruited to participate.

Results

A total of 14 residents participated in the study. The median correct response rate was 2 of 5 (40\%; range: 0-4) for the 2D group, and 3 of 5 (60\%; range: 1-5) for the 3D group (p \< 0.01). The average time to complete each plan was 156 {\textpm} 107 seconds for the 2D group, and 84 {\textpm} 73 seconds for the 3D group (p \< 0.01). A total 13 of 14 residents found the 3D model easier to use than the 2D. Most residents noticed a difference between the 2 modalities and found that the 3D model improved their confidence with the surgical plan proposed.

Conclusions

The results of this study show that 3D reconstruction for liver surgery planning increases accuracy of resident surgical planning and decreases amount of time required. 3D reconstruction would be a useful model for improving trainee understanding of liver anatomy and surgical resection, and would serve as an adjunct to current 2D planning methods. This has the potential to be developed into a module for teaching liver surgery in a competency-based medical curriculum.

}, doi = {http://dx.doi.org/10.1016/j.jsurg.2017.07.031}, author = {Yeo, Caitlin T and MacDonald, Andrew and Tamas Ungi and Andras Lasso and Diederick Jalink and Boris Zevin and Gabor Fichtinger and Nanji, Sulaiman} } @conference {Harish2015, title = {Intraoperative visualization and assessment of electromagnetic tracking error}, booktitle = {SPIE Medical Imaging 2015}, volume = {9415}, year = {2015}, pages = {94152H-94152H-6}, address = {Orlando,FL, United States, Feb. 23, 2015}, abstract = {

Electromagnetic tracking allows for increased flexibility in designing image-guided interventions, however it is well understood that electromagnetic tracking is prone to error. Visualization and assessment of the tracking error should take place in the operating room with minimal interference with the clinical procedure. The goal was to achieve this ideal in an open-source software implementation in a plug and play manner, without requiring programming from the user. We use optical tracking as a ground truth. An electromagnetic sensor and optical markers are mounted onto a stylus device, pivot calibrated for both trackers. Electromagnetic tracking error is defined as difference of tool tip position between electromagnetic and optical readings. Multiple measurements are interpolated into the thin-plate B-spline transform visualized in real time using 3D Slicer. All tracked devices are used in a plug and play manner through the open-source SlicerIGT and PLUS extensions of the 3D Slicer platform. Tracking error was measured multiple times to assess reproducibility of the method, both with and without placing ferromagnetic objects in the workspace. Results from exhaustive grid sampling and freehand sampling were similar, indicating that a quick freehand sampling is sufficient to detect unexpected or excessive field distortion in the operating room. The software is available as a plug-in for the 3D Slicer platforms. Results demonstrate potential for visualizing electromagnetic tracking error in real time for intraoperative environments in feasibility clinical trials in image-guided interventions.

}, doi = {10.1117/12.2082330}, url = {http://dx.doi.org/10.1117/12.2082330}, author = {Vinyas Harish and Tamas Ungi and Andras Lasso and MacDonald, Andrew and Nanji, Sulaiman and Gabor Fichtinger} }