Ivan George

Live augmented reality: a new visualization method for laparoscopic surgery using continuous volumetric computed tomography

BackgroundCurrent laparoscopic images are rich in surface detail but lack information on deeper structures. This report presents a novel method for highlighting these structures during laparoscopic surgery using continuous multislice computed tomography (CT). This has resulted in a more accurate augmented reality (AR) approach, termed “live AR,” which merges three-dimensional (3D) anatomy from live low-dose intraoperative CT with live images from the laparoscope.MethodsA series of procedures with swine was conducted in a CT room with a fully equipped laparoscopic surgical suite. A 64-slice CT scanner was used to image the surgical field approximately once per second. The procedures began with a contrast-enhanced, diagnostic-quality CT scan (initial CT) of the liver followed by continuous intraoperative CT and laparoscopic imaging with an optically tracked laparoscope. Intraoperative anatomic changes included user-applied deformations and those from breathing. Through deformable image registration, an intermediate image processing step, the initial CT was warped to align spatially with the low-dose intraoperative CT scans. The registered initial CT then was rendered and merged with laparoscopic images to create live AR.ResultsSuperior compensation for soft tissue deformations using the described method led to more accurate spatial registration between laparoscopic and rendered CT images with live AR than with conventional AR. Moreover, substitution of low-dose CT with registered initial CT helped with continuous visualization of the vasculature and offered the potential of at least an eightfold reduction in intraoperative X-ray dose.ConclusionsThe authors proposed and developed live AR, a new surgical visualization approach that merges rich surface detail from a laparoscope with instantaneous 3D anatomy from continuous CT scanning of the surgical field. Through innovative use of deformable image registration, they also demonstrated the feasibility of continuous visualization of the vasculature and considerable X-ray dose reduction. This study provides motivation for further investigation and development of live AR.

Radio Frequency Identification Systems Technology in the Surgical Setting

Radio frequency identification (RFID) is a technology that will have a profound impact on medicine and the operating room of the future. The purpose of this article is to provide an introduction to this exciting technology and a description of the problems in the perioperative environment that RFID might address to improve safety and increase productivity. Although RFID is still a nascent technology, applications are likely to become much more visible in patient care and treatment areas and will raise questions for practitioners. We also address both the current limitations and what appear to be reasonable near-future possibilities.

Postural instability does not necessarily correlate to poor performance: case in point

BackgroundIt is very important for surgeons who perform minimally invasive surgery (MIS) to maintain proper postural stability, which kinematic research can determine. Previous studies in surgical ergonomics have shown that postural stability is correlated to instrument type, task difficulty, and skill level. What should also be considered is that surgeons may strategically change stance or joint movement to achieve better surgical outcomes while potentially subjecting themselves to greater risk. Background information about subjects, e.g., joint impairment, should be considered an important surgical ergonomic element. Such information can lead to more realistic and accurate conclusions about postural stability and joint kinematics.MethodsA highly experienced and skilled right-handed surgeon developing carpal tunnel syndrome in both wrists was recruited into a small (6 subjects) performance study of pegboard transfer and circle-cutting tasks from the Fundamentals of Laparoscopic Surgery (FLS) skill set. Joint kinematics and postural data were collected using two associated force plates and a motion capture system of 12 digital, high-resolution, high-speed, infrared cameras.ResultsEach task was completed in less than 90 s. In pegboard transfer, the subject increased shoulder abduction angle to align his hand and forearm and minimize wrist flexion. When circle-cutting required excessive wrist flexion, the subject maintained his lower body position and stance while twisting his torso, a strategy that appeared to stabilize tangential direction related to cutting while maintaining a fixed orientation of forearm, wrist, and hand. In another circle-cutting trial, the subject changed his stance primarily by shifting foot position as necessary to obtain better scissor approach angles. These compensatory, strategic movements caused an increase in overall postural sway but did not represent postural instability.ConclusionThis case study indicated that poor joint kinematics or postural stability does not necessarily correlate to poor performance. Instead, they may indicate positive compensatory or strategic movements.

Evaluation of surgical performance during laparoscopic incisional hernia repair: a multicenter study

BackgroundLaparoscopic incisional hernia repair (LIHR) is a common procedure requiring advanced laparoscopic skills. This study aimed to develop a procedure-specific tool to assess the performance of LIHR and to evaluate its reliability and validity.MethodsThe Global Operative Assessment of Laparoscopic Skills-Incisional Hernia (GOALS-IH) is a 7-item global rating scale developed by experts to evaluate the steps of LIHR (placement of trocars, adhesiolysis, estimation of mesh size and shape, mesh orientation and positioning, mesh fixation, knowledge and autonomy in use of instruments, overall competence), each rated on a 5-point Likert scale. During LIHR, 13 attending surgeons and fellows experienced in minimally invasive surgery (MIS) and 19 novice surgeons (postgraduate years [PGYs], 3–5) were evaluated at four teaching hospitals by the attending surgeon, a trained observer, and self-assessment using GOALS-IH, and by a previously validated 5-item general laparoscopic rating scale (GOALS). Interrater reliability was assessed by intraclass correlation (ICC), and internal consistency of rating items was assessed by Cronbach’s alpha. Known-groups construct validity was assessed by using the t-test and by correlating of the number of self-reported LIHR cases with the total score. Concurrent validity was assessed by correlating the GOALS-IH score with the GOALS general rating scale. Data are presented as mean and 95% confidence interval (CI).ResultsInterrater reliability for the total GOALS-IH score was 0.79 (95% CI, 0.60–0.89) between observers and attending surgeons, 0.81 (95% CI, 0.58–0.92) between participants and attending surgeons, and 0.89 (95% CI, 0.76–0.96) between participants and observers. Internal consistency was high (Cronbach’s alpha, 0.93). Experienced surgeons performed significantly better than novices as assessed by GOALS-IH (31; 95% CI, 29–33 vs. 21; 95% CI, 19–24; pxa0<xa00.01). Very good correlation was found between GOALS-IH and previous LIHR experience (rxa0=xa00.82; pxa0<xa00.01) and strong correlation between GOALS-IH and generic GOALS total scores (rxa0=xa00.90; pxa0<xa00.01).ConclusionSurgical performance during clinical LIHR can be assessed reliably using GOALS-IH. Results can be used to provide formative feedback to the surgeon and to identify steps of the operation that would benefit from specific educational interventions.

Performance of simulated laparoscopic incisional hernia repair correlates with operating room performance.

BACKGROUNDnthe role of simulation for training in procedures such as laparoscopic incisional hernia repair (LIHR) is unknown. The purpose of this study was to determine whether performance in simulated LIHR correlates with operating room (OR) performance.nnnMETHODSnsubjects performed LIHR in the University of Maryland Surgical Abdominal Wall (SAW) simulator and the OR. Trained observers used a LIHR-specific global rating scale (Global Operative Assessment of Laparoscopic Skills-Incisional Hernia) to assess performance. Global Operative Assessment of Laparoscopic Skills-Incisional Hernia includes 7 domains (trocar placement, adhesiolysis, mesh sizing, mesh positioning, mesh fixation, knowledge and autonomy in instrument use, and overall competence). The correlation between simulator and OR performance was assessed using the Pearson coefficient.nnnRESULTSnfourteen surgeons from 2 surgical departments participated. Experienced surgeons (n = 9) were defined as attending surgeons and minimally invasive surgury (MIS) fellows, and novice surgeons (n = 5) were general surgery residents (postgraduate years 3-5). The correlation between performance in the OR and the simulator for the entire group was .87 (95% confidence interval, .63-.96; P < .001).nnnCONCLUSIONSnthere was an excellent correlation between LIHR performance in the simulator and clinical LIHR. This suggests that performance in the SAW simulator may predict performance in the operating room.

Surgical Abdominal Wall (SAW): A Novel Simulator for Training in Ventral Hernia Repair

Laparoscopic ventral hernia repair (LVHR) is a relatively common procedure that requires advanced minimally invasive surgical skills to perform. The role for simulation is increasingly supported as an effective way to teach surgical skills and accelerate the learning curve. This article describes The University of Maryland’s Surgical Abdominal Wall, an inexpensive procedure-specific physical simulator for LVHR, and summarizes the authors’ early experiences using this model in a curriculum for surgery residents.

GOALS-Incisional Hernia: A Valid Assessment of Simulated Laparoscopic Incisional Hernia Repair

The Global Operative Assessment of Laparoscopic Skills (GOALS) is a valid and reliable measure of basic, non-procedure-specific laparoscopic skills. GOALS-incisional hernia (GOALS-IH) was developed to evaluate performance of laparoscopic incisional hernia repair (LIHR). The purpose of this study was to assess the validity and reliability of GOALS-IH during LIHR simulation. GOALS-IH assesses 7 domains with a maximum score of 35. A total of 12 experienced surgeons and 10 novices performed LIHR on the Surgical Abdominal Wall simulator. Performance was assessed by a trained observer and by self-assessment using GOALS-IH, basic GOALS and a visual analog scale (VAS) for overall competence. Both interrater reliability and internal consistency were high (.76 and .95 respectively). Experienced surgeons had higher mean GOALS-IH scores than novices (32.3 ± 2 versus 22.7 ± 5). There was excellent correlation between GOALS-IH and other measures of performance (GOALS r = .93 and VAS r = .93). GOALS-IH is easy to use, valid and reliable for assessment of simulated LIHR.

Classification of hiatal hernias using dynamic three-dimensional reconstruction.

Hiatal hernias and paraesophageal hernias are common clinical entities and have a well-known classification system. Multiple modalities have been used to illustrate these hernias, most relying on artists’ renderings or two-dimensional radiographic studies. However, surgeons would benefit from a comprehensive graphic representation of hiatal hernias based on current imaging technologies. We have applied polygonal mesh surface modeling techniques to render dynamic three-dimensional computed tomography-based models of the four recognized types of hiatal hernias. The resulting images allow nearly real-time navigation in an intuitive and clinically relevant fashion. This model should clarify and eventually advance the existing classification by applying modern and sophisticated image processing to established concepts.

Development of continuous CT-guided minimally invasive surgery

Minimally invasive laparoscopic surgeries are known to lead to improved outcomes, less scarring, and significantly faster patient recovery as compared with conventional open invasive surgeries. Laparoscopes, used to visualize internal anatomy and guide laparoscopic surgeries, however, remain limited in visualization capability. Not only do they provide a relatively flat representation of the three-dimensional (3D) anatomy, they show only the exposed surfaces. A surgeon is thus unable to see inside a structure, which limits the precision of current-generation minimally invasive surgeries and is often a source of complications. To see inside a structure before dissecting it has been a long-standing need in minimally invasive laparoscopic surgeries, a need that laparoscopy is fundamentally limited in meeting. In this work we propose to use continuous computed tomography (CT) of the surgical field as a supplementary imaging tool to guide laparoscopic surgeries. The recent emergence of 64-slice CT and its continuing evolution make it an ideal candidate for four-dimensional (3D space + time) intraoperative imaging. We also propose a novel, elastic image registration-based technique to keep the net radiation dose within acceptable levels. We have successfully created 3D renderings from multislice CT corresponding to anatomy visible within the field of view of the laparoscope in a swine. These renderings show the underlying vasculature along with their latest intraoperative orientation. With additional developments, our research has the potential to help improve the precision of laparoscopic surgeries further, reduce complications, and expand the scope of minimally invasive surgeries.

Ergonomic safety of surgical techniques and standing positions associated with laparoscopic cholecystectomy

Laparoscopic cholecystectomy (LC), a procedure in which, using either a one-handed or two-handed technique, a surgeon removes a symptomatic gallbladder in a minimally invasive manner, is commonly—due to its relatively high safety level—the initial procedure that a resident will perform. Investigation of the ergonomics associated with LC one-handed and two-handed techniques is one goal of this study. Identification of which of two standing positions (between legs or at side) used during LC is the more ergonomically favorable is the other. Knowledge gained from our research in these issues is intended to be applicable both to surgical training and the operating room environment. Eight right-handed laparoscopic surgeons with varying levels of surgical skills were recruited for this study. Each performed LC a total of four times on a virtual reality (VR) simulator with each performance incorporating one of the following conditions: either the one-handed or two-handed surgical technique or the position of standing between the patients legs or at the patients side. Each trial was also divided into two phases: 1) dissection and clipping and 2) gall bladder removal. During the performance of LC, physical ergonomic data were collected though surface electrode electromyography (EMG) and two force plates. Additionally NASA-Task Load Index (TLX) and secondary time estimation were used for cognitive ergonomic assessment. Standing at the side produced a significantly higher weight-loading ratio (WLR) than standing between the legs. Comparison between techniques indicated that the two-handed technique caused higher WLR. Significant phase effect equated increased WLR with phase 2 gall bladder removal. No statistical interactions among technique, standing position, and phase were significant. Analysis of NASA-TLX showed that global workload, influenced mainly by significant physical workload and effort scales, was higher with the side-standing position and the two-handed technique. The results from time estimation analysis, although statistically marginal, demonstrated that the one-handed technique is more mentally demanding. Our study demonstrated that due to lower physical as well as mental workload, the two-handed technique performed with the surgeon positioned between the patients legs is the most ergonomically favorable combination. Additionally, it was demonstrated that the pedal for cautery operation requires ergonomic improvement. These specific findings encourage us to continue research into what proof ergonomics can provide regarding what constitutes the most efficacious approaches to surgical procedures and to optimizing patient safety and the surgical environment.