Interpretation of three-dimensional structure from two-dimensional endovascular images: implications for educators in vascular surgery

Video Context Improves Performance in Identifying Operative Planes on Static Surgical Images

BACKGROUND

Correct identification of the surgical tissue planes of dissection is paramount at the operating room, and the needed skills seem to be improved with realistic dynamic models rather than mere still images. The objective is to assess the role of adding video prequels to still images taken from operations on the precision and accuracy of tissue plane identification using a validated simulation model, considering various levels of surgeons' experience.

METHODS

A prospective observational study was conducted involving 15 surgeons distributed to three equal groups, including a consultant group [C], a senior group [S], and a junior group [J]. Subjects were asked to identify and draw ideal tissue planes in 20 images selected at suitable operative moments of identification before and after showing a 10- second videoclip preceding the still image. A validated comparative metric (using a modified Hausdorff distance [%Hdu] for object matching) was used to measure the distance between lines. A precision analysis was carried out based on the difference in %Hdu between lines drawn before and after watching the videos, and between-group comparisons were analyzed using a one-way analysis of variance (ANOVA). The analysis of accuracy was done on the difference in %Hdu between lines drawn by the subjects and the ideal lines provided by an expert panel. The impact of videos on accuracy was assessed using a repeated-measures ANOVA.

RESULTS

The C group showed the highest preciseness as compared to the S and J groups (mean Hdu 9.17±11.86 versus 12.1±15.5 and 20.0±18.32, respectively, p <0.001) and significant differences between groups were found in 14 images (70%). Considering the expert panel as a reference, the interaction between time and experience level was significant ( F (2, 597) = 4.52, p <0.001). Although the subjects of the J group were significantly less accurate than other surgeons, only this group showed significant improvements in mean %Hdu values after watching the lead-in videos ( F (1, 597) = 6.04, p = 0.014).

CONCLUSIONS

Adding video context improved the ability of junior trainees to identify tissue planes of dissection. A realistic model is recommended considering experience-based differences in precision in training programs.

Recent evidence on visual-spatial ability in surgical education: A scoping review

BACKGROUND

Understanding the relationships between structures is critical for surgical trainees. However, the heterogeneity of the literature on visual-spatial ability (VSA) in surgery makes it challenging for educators to make informed decisions on incorporating VSA into their programs. We conducted a scoping review of the literature on VSA in surgery to provide a map of the literature and identify where gaps still exist for future research.

METHODS

We searched databases until December 2019 using keywords related to VSA and surgery. The resulting articles were independently screened by two researchers for inclusion in our review.

RESULTS

We included 117 articles in the final review. Fifty-nine articles reported significant correlations between VSA tests and surgical performance, and this association is supported by neuroimaging studies. However, it remains unclear whether VSA should be incorporated into trainee selection and whether there is a benefit of three-dimensional (3D) over two-dimensional (2D) training.

CONCLUSIONS

It appears that VSA correlates with surgical performance in the simulated environment, particularly for novice learners. Based on our findings, we make suggestions for how surgical educators may use VSA to support novice learners. Further research should determine whether VSA remains correlated to surgical performance when trainees move into the operative environment.

Spatial abilities training in the field of technical skills in health care: A systematic review

Objective

To conduct a systematic review of the effect of interventions on spatial abilities in the field of technical skills in health care.

Methods

A literature search was conducted up to November 14, 2017 in Scopus and in several databases on EBSCOhost platform. Citations were obtained, articles related to retained citations were reviewed and a final list of included studies was identified. Methods in the field of technical skills relating an intervention to spatial abilities test scores between intervention groups or obtained before and after the intervention were identified as eligible. The quality of included studies was assessed and data were extracted in a systematic way.

Results

A series of 5513 citations was obtained. Ninety-nine articles were retained and fully reviewed, yielding four included studies. No difference in the Hidden Figure Test score after one year was observed after residency training in General Surgery of at least nine months. A first-year dental curriculum was not found to elevate the Novel Object Cross-Sections Test score (P = 0.07). A two-semester learning period of abdominal sonography was found to increase the Revised Minnesota Paper Form Board Test score (P < 0.05). A hands-on radiology course using interactive three-dimensional image post-processing software consisting of seven two-hour long seminars on a weekly basis was found to amplify the Cube Perspective Test score (P < 0.001).

Conclusion

Spatial abilities tests scores were enhanced by courses in abdominal sonography and hands-on radiology, but were not improved by residency training in General Surgery and first-year dental curriculum.

3D-printed model improves clinical assessment of surgeons on anatomy

Performing surgical procedures often requires a surgeon to develop a skill to create 3-dimensional (3D) mental model on patient's anatomy. Question remains whether the touching on the 3D printed model can facilitate learning of patient anatomy than viewing the rendered virtual on-screen model. The printed and the virtual 3D model were developed from CT films taken from a 4-year-old girl, who had dysplasia of the hip in the left hip. Eleven subjects were called to report measures on six key anatomical features on the hips. The reporting time and the accuracy were compared between the two models, along with the gaze characteristics of subjects while inspecting the models. The variables were analysed using a 2 × 2 within subject ANOVA to examine the difference between viewing the models (on-screen vs. printed-out) and the side of the hip (right vs. left). Interacting with the printed 3D model required shorter times and yielded more accurate visual judgments than viewing the virtual models on most of the anatomical features. Subjects performed a fewer number of fixations but with a longer mean fixation duration when interacting the printed than inspecting the virtual on-screen 3D model. Results confirmed the value of the printed 3D model on improving the clinical judgement on patient anatomy. Confidence in collecting information from the physical world and the cross-model sensor integration may explain why participants performed better with the printed model compared to the virtual model.

A Pilot Study Assessing the Impact of 3-D Printed Models of Aortic Aneurysms on Management Decisions in EVAR Planning

Introduction:

Endovascular repair of aortic aneurysms with difficult anatomy is challenging. There is no consensus for planning such procedures.

Methods:

Six cases of aortic aneurysms with challenging anatomical features, such as short, angulated, and conical necks and tortuous iliacs were harvested. The computed tomography (CT) scans were anonymized. Lifesize 3-dimensional (3-D) printed models were created of the lumen. Endovascular operators were asked to review the CT angiography (CTA), make a management plan, and give an indication of their confidence. They were then presented with the equivalent model and asked to review their decision. Their attitudes to such models were briefly surveyed.

Results:

A total of 28 endovascular operators reviewed 144 cases. After review of the physical model, the management plan changed in 29 (20.1%) of 144 cases. Initial plan after CTA review was endovascular 73.6%, open repair 22.9%, and second opinion 3.5%. After model review, this became endovascular 67.4%, open repair 19.4%, and second opinion 4.8%. Although the general trend was toward more open procedures, off-label techniques reduced from 19.4% to 15.2% following model review. When the management plan did not change, level of confidence did increase in 37 (43.5%) of 85 cases. The majority of operators stated that they would find models useful for planning in some procedures. For 1 case, the change in the percentage of participants being sure in the management plan was statistically significant ( P = .031).

Conclusion:

The 3-D printed models may be potentially useful in planning cases with EVAR. It is a paradigm that warrants further investigation.

A novel method for assessing visual perception of surgical planes

BACKGROUND

Recognition of tissue planes during surgery appears to be a skill acquired with experience. We conducted a pilot study to test this hypothesis using a novel method for evaluating this skill in a simulated environment.

METHODS

Twelve surgeons of varying levels of experience were shown 16 captured images from a mesorectal excision. For each image, they were asked to draw the ideal dissection plane with a stylus on a tablet computer. We used a novel metric for comparing agreement between lines to determine the level of precision observed between junior and senior trainees and consultant surgeons and measure the accuracy of junior and senior trainees compared with consultant surgeons.

RESULTS

We observed significant differences in precision for 9 of 16 images; 7 of these followed the predicted stepwise pattern associated with level of experience. Using consultant surgeons as the reference standard, we observed significant differences in accuracy between senior and junior trainees for 11 images, with senior trainees being more accurate in 10 of them. Only 2 images failed to contribute significant findings to our analysis.

CONCLUSION

The findings of this pilot evaluation of a novel method for measuring a surgeon's ability to recognize tissue planes in a simulated model show that skill improves with experience. Further evaluation of this method will reveal its utility as an assessment tool and possibly as a training instrument.

Fine-motor skills testing and prediction of endovascular performance

BACKGROUND

Performing endovascular procedures requires good control of fine-motor digital movements and hand-eye coordination. Objective assessment of such skills is difficult. Trainees acquire control of catheter/wire movements at various paces. However, little is known to what extent talent plays for novice candidates at entry to practice.

PURPOSE

To study the association between performance in a novel aptitude test of fine-motor skills and performance in simulated procedures.

MATERIAL AND METHODS

The test was based on manual course-tracking using a proprietary hand-operated roller-bar device coupled to a personal computer with monitor view rotation. A total of 40 test repetitions were conducted separately with each hand. Test scores were correlated with simulator performance. Group A (n = 14), clinicians with various levels of endovascular experience, performed a simulated procedure of contralateral iliac artery stenting. Group B (n = 19), medical students, performed 10 repetitions of crossing a challenging aortic bifurcation in a simulator.

RESULTS

The test score differed markedly between the individuals in both groups, in particular with the non-dominant hand. Group A: the test score with the non-dominant hand correlated significantly with simulator performance assessed with the global rating scale SAVE (R = -0.69, P = 0.007). There was no association observed from performances with the dominant hand. Group B: there was no significant association between the test score and endovascular skills acquisition neither with the dominant nor with the non-dominant hand.

CONCLUSION

Clinicians with increasing levels of endovascular technical experience had developed good fine-motor control of the non-dominant hand, in particular, that was associated with good procedural performance in the simulator. The aptitude test did not predict endovascular skills acquisition among medical students, thus, cannot be suggested for selection of novice candidates. Procedural experience and practice probably supplant the influence of innate abilities (talent) over time.

Three-dimensional aortic aneurysm model and endovascular repair: an educational tool for surgical trainees

OBJECTIVES

Endovascular aortic aneurysm repair (EVAR) is a current valid treatment option for patients with abdominal aortic aneurysms (AAAs). The success of EVAR depends on the selection of appropriate patients, which requires detailed knowledge of the patient's vascular anatomy and preoperative planning. Three-dimensional (3D) models of AAA using a rapid prototyping technique were developed to help surgical trainees learn how to plan for EVAR more effectively.

METHOD

Four cases of AAA were used as prototypes for the models. Nine questions associated with preoperative planning for EVAR were developed by a group of experts in the field of endovascular surgery. Forty-three postgraduate trainees in general surgery participated in the present study. The participants were randomly assigned into two groups. The 'intervention' group was provided with the rapid prototyping AAA models along with 3D computed tomography (CT) corresponding to the cases of the test, while the control group was provided with 3D CTs only.

RESULTS

Differences in the scores between the groups were tested using the unpaired t test. The mean test scores were consistently and significantly higher in the 3D CT group with models compared with the 3D CT group without models for all four cases. Age, year of training, sex and previous EVAR experience had no effect on the scores.

CONCLUSION

The 3D aortic aneurysm model constructed using the rapid prototype technique may significantly improve the ability of trainees to properly plan for EVAR.

Evaluation of task performance during mentally imaging three-dimensional shapes from plane figures

Mental imagery is an important theme in psychology. Although the mental rotation task is well known, the complicated functions in mental images with higher spatial perception remain unknown. The aim of this study was to evaluate the task performances during the mental imaging of two- or three-dimensional shapes (14 healthy male students, M age = 24.2 yr., SD = 3.4). The mental-image task to frame a 3D object from actual 2D figures (2D-3D task) had the longest reaction time (p < .01); performance accuracy on this task was lower than for other tasks. The reaction time for the 2D-3D task differed statistically significantly from that on the typical working memory task using the mental image of three 2D figures. Compared with the 2D-3D task, illustration of a simple 3D object would be effective when a quick judgment of high accuracy is required. The feasibility study using an electroencephalogram suggests that the theta-band activity at the middle frontal lobe reflecting the acts of the working memory is related with mental images.

The effect of viewing angle on wrist posture estimation from photographic images using novice raters

Observational assessment of wrist posture using photographic methods is theoretically affected by camera view angle. A study was conducted to investigate whether wrist flexion/extension and radial/ulnar deviation postures were estimated differently by raters depending on the viewing angle and compared to predictions using a quantitative 2D model of parallax. Novice raters (n=26) estimated joint angles from images of wrist postures photographed from ten different viewing angles. Results indicated that ideal views, orthogonal to the plane of motion, produced more accurate estimates of posture compared to non-ideal views. The neutral (0°) posture was estimated the most accurately even at different viewing angles. Raters were more accurate than model predictions. Findings demonstrate a need for more systematic methods for collecting and analyzing photographic data for observational studies of posture. Renewed caution in interpreting existing studies of wrist posture where viewing angle was not controlled is advised.

Three-dimensional endoscopic pituitary surgery

OBJECTIVE

We describe a novel 3-dimensional (3-D) stereoendoscope and discuss our early experience using it to provide improved depth perception during transsphenoidal pituitary surgery.

METHODS

Thirteen patients underwent endonasal endoscopic transsphenoidal surgery. A 6.5-, 4.9-, or 4.0-mm, 0- and 30-degree rigid 3-D stereoendoscope (Visionsense, Ltd., Petach Tikva, Israel) was used in all cases. The endoscope is based on "compound eye" technology, incorporating a microarray of lenses. Patients were followed prospectively and compared with a matched group of patients who underwent endoscopic surgery with a 2-dimensional (2-D) endoscope. Surgeon comfort and/or complaints regarding the endoscope were recorded.

RESULTS

The 3-D endoscope was used as the sole method of visualization to remove 10 pituitary adenomas, 1 cystic xanthogranuloma, 1 metastasis, and 1 cavernous sinus hemangioma. Improved depth perception without eye strain or headache was noted by the surgeons. There were no intraoperative complications. All patients without cavernous sinus extension (7of 9 patients) had gross tumor removal. There were no significant differences in operative time, length of stay, or extent of resection compared with cases in which a 2-D endoscope was used. Subjective depth perception was improved compared with standard 2-D scopes.

CONCLUSION

In this first reported series of purely 3-D endoscopic transsphenoidal pituitary surgery, we demonstrate subjectively improved depth perception and excellent outcomes with no increase in operative time. Three-dimensional endoscopes may become the standard tool for minimal access neurosurgery.

Comparison of learning curves and skill transfer between classical and robotic laparoscopy according to the viewing conditions: implications for training

BACKGROUND

The purpose of this study was to evaluate the perceptual (2-dimensional [2D] vs. 3-dimensional [3D] view) and instrumental (classical vs. robotic) impacts of new robotic system on learning curves.

METHODS

Forty medical students without any surgical experience were randomized into 4 groups (classical laparoscopy with 3D-direct view or with 2D-indirect view, robotic system in 3D or in 2D) and repeated a laparoscopic task 6 times. After these 6 repetitions, they performed 2 trials with the same technique but in the other viewing condition (perceptive switch). Finally, subjects performed the last 3 trials with the technique they never used (technical switch). Subjects evaluated their performance answering a questionnaire (impressions of mastery, familiarity, satisfaction, self-confidence, and difficulty).

RESULTS

Our study showed better performance and improvement in 3D view than in 2D view whatever the instrumental aspect. Participants reported less mastery, familiarity, and self-confidence and more difficulty in classical laparoscopy with 2D-indirect view than in the other conditions.

CONCLUSIONS

Robotic surgery improves surgical performance and learning, particularly by 3D view advantage. However, perceptive and technical switches emphasize the need to adapt and pursue training also with traditional technology to prevent risks in conversion procedure.

Visual-spatial ability and interpretation of three-dimensional information in radiographs

OBJECTIVES

To investigate whether skill in the interpretation of three-dimensional (3D) information in radiographs utilizing the parallax phenomenon is associated with visual-spatial ability and whether development of this skill is related to visual-spatial ability.

METHODS

Eighty-six individuals with a median age of 25 years participated in the study. It was organized into three parts: (1) assessment before training, (2) training in object depth localization utilizing parallax and (3) assessment after training. Before training, visual-spatial ability was assessed with a mental rotation test, MRT-A; skill in interpreting 3D information was assessed with two specifically designed proficiency tests: a radiography test, which assessed the ability to interpret 3D information in radiographs utilizing motion parallax and a principle test which assessed understanding of the principles of motion parallax. After training, skill in interpreting 3D information was reassessed. Improvement was defined as the difference between test scores after training and before training. Multiple linear regression was used to analyse the effect of student and training characteristics on proficiency test results and improvement.

RESULTS

Radiography test results after training and improvement of radiography test results were significantly associated with MRT-A scores (P<0.001 and P=0.020, respectively). Principle test results were high before training and did not improve after training. The test results were associated with MRT-A both before (P=0.009) and after training (P=0.003).

CONCLUSIONS

Understanding of the parallax phenomenon is associated with visual-spatial ability. Development of the skill to interpret 3D information in radiographs utilizing parallax is facilitated for individuals with high visual-spatial ability.

Predicting the technical competence of surgical residents

I describe an approach to predicting competence in technical skills for the purposes of resident selection. To demonstrate a predictive relationship, it is necessary to use measures that exhibit variation, reliability, and validity. There is little evidence that such measures are routinely used in the process of selecting residents. I argue that the selection of assessment instruments in the predictor domain must be guided by relevant theoretical considerations, while assessment in the surgical domain must make use of more objective and reliable instruments than is currently the practice. I present a brief summary of research on predicting operative technical competence.

High-level visual-spatial ability for novices correlates with performance in a visual-spatial complex surgical simulator task

BACKGROUND

This study addresses how high-level visual-spatial ability of surgical novices is related to performance of two simulator tasks with (KSA) and without (MIST) anatomic graphics and haptic feedback, differing in visual-spatial complexity.

METHODS

Visual-spatial test scores assessed by Mental Rotation Test (MRT) and BasIQ and performance scores for Instrument Navigation (IN) in Key Surgical Activities (Procedicus KSA) and Manipulate and Diathermy (MD) in Minimally Invasive Surgical Trainer (Procedicus MIST) were correlated for 54 Swedish surgical novices.

RESULTS

Significant Pearson's r correlations were obtained between visual-spatial scores measured by MRT-C and total score from the last trial for IN (r = 0.278, p < 0.05). Visual-spatial scores (measured by BasIQ) also correlated with total score from the first trial (r = 0.443, p < 0.05) and from the last trial (r = 0.489, p < 0.05).

CONCLUSION

High-level visual-spatial ability is important for surgical novices to possess in the early training phase of a visual-spatial complex task in KSA.

Advantage of three dimensional animated teaching over traditional surgical videos for teaching ophthalmic surgery: a randomised study

BACKGROUND/AIM

Owing to the complex topographical aspects of ophthalmic surgery, teaching with conventional surgical videos has led to a poor understanding among medical students. A novel multimedia three dimensional (3D) computer animated program, called "Ophthalmic Operation Vienna" has been developed, where surgical videos are accompanied by 3D animated sequences of all surgical steps for five operations. The aim of the study was to assess the effect of 3D animations on the understanding of cataract and glaucoma surgery among medical students.

METHOD

Set in the Medical University of Vienna, Department of Ophthalmology, 172 students were randomised into two groups: a 3D group (n=90), that saw the 3D animations and video sequences, and a control group (n=82), that saw only the surgical videos. The narrated text was identical for both groups. After the presentation, students were questioned and tested using multiple choice questions.

RESULTS

Students in the 3D group found the interactive multimedia teaching methods to be a valuable supplement to the conventional surgical videos. The 3D group outperformed the control group not only in topographical understanding by 16% (p<0.0001), but also in theoretical understanding by 7% (p<0.003). Women in the 3D group gained most by 19% over the control group (p<0.0001).

CONCLUSIONS

The use of 3D animations lead to a better understanding of difficult surgical topics among medical students, especially for female users. Gender related benefits of using multimedia should be further explored.