Zsuzsanna Keri

Spinal Curvature Measurement by Tracked Ultrasound Snapshots

Monitoring spinal curvature in adolescent kyphoscoliosis requires regular radiographic examinations; however, the applied ionizing radiation increases the risk of cancer. Ultrasound imaging is favored over radiography because it does not emit ionizing radiation. Therefore, we tested an ultrasound system for spinal curvature measurement, with the help of spatial tracking of the ultrasound transducer. Tracked ultrasound was used to localize vertebral transverse processes as landmarks along the spine to measure curvature angles. The method was tested in two scoliotic spine models by localizing the same landmarks using both ultrasound and radiographic imaging and comparing the angles obtained. A close correlation was found between tracked ultrasound and radiographic curvature measurements. Differences between results of the two methods were 1.27 ± 0.84° (average ± SD) in an adult model and 0.96 ± 0.87° in a pediatric model. Our results suggest that tracked ultrasound may become a more tolerable and more accessible alternative to radiographic spine monitoring in adolescent kyphoscoliosis.

Real-time workflow detection using webcam video for providing real-time feedback in central venous catheterization training.

Purpose: Medical schools are shifting from a time-based approach to a competency-based education approach. A competency-based approach requires continuous observation and evaluation of trainees. The goal of Central Line Tutor is to be able to provide instruction and real-time feedback for trainees learning the procedure of central venous catheterization, without requiring a continuous expert observer. The purpose of this study is to test the accuracy of the workflow detection method of Central Line Tutor. This study also looks at the effectiveness of object recognition from a webcam video for workflow detection. Methods: Five trials of the procedure were recorded from Central Line Tutor. Five reviewers were asked to identify the timestamp of the transition points in each recording. Reviewer timestamps were compared to those identified by Central Line Tutor. Differences between these values were used to calculate average transitional delay. Results: Central Line Tutor was able to identify 100% of transition points in the procedure with an average transitional delay of -1.46 ± 0.81s. The average transitional delay of EM and webcam tracked steps were -0.35 ± 2.51s and -2.46 ± 3.57s respectively. Conclusions: Central line tutor was able to detect completion of all workflow tasks with minimal delay and may be used to provide trainees with real-time feedback. The results also show that object recognition from a webcam video is an effective method for detecting workflow tasks in the procedure of central venous catheterization.

A learning curve analysis of ultrasound-guided in-plane and out-of-plane vascular access training with Perk Tutor.

PURPOSE: Under ultrasound guidance, procedures that have been traditionally performed using landmark approaches have become safer and more efficient. However, inexperienced trainees struggle with coordinating probe handling and needle insertion. We aimed to establish learning curves to identify the rate of acquisition of in-plane and out-of-plane vascular access skill in novice medical trainees. METHODS: Thirty-eight novice participants were randomly assigned to perform either in-plane or out-of-plane insertions. Participants underwent baseline testing, four practice insertions (with 3D visualization assistance), and final testing; performance metrics were computed for all procedures. Five expert participants performed insertions in both approaches to establish expert performance metric benchmarks. RESULTS: In-plane novices (n=19) demonstrated significant final reductions in needle path inefficiency (45.8 vs. 127.1, p<0.05), needle path length (41.1 mm vs. 58.0 mm, p<0.05), probe path length (11.6 mm vs. 43.8 mm, p<0.01), and maximal distance between needle and ultrasound plane (3.1 mm vs. 5.5 mm, p<0.05) and surpassed expert benchmarks in average and maximal rotational error. Out-of-plane novices (n=19) demonstrated significant final reductions in all performance metrics, including needle path inefficiency (54.4 vs. 1102, p<0.01), maximum distance of needle past plane (0.0 mm vs. 7.3 mm, p<0.01), and total time of needle past plane (0.0 s vs. 3.4 s, p<0.01) and surpassed expert benchmarks in maximum distance and time of needle past plane. CONCLUSION: Our learning curves quantify improvement in in-plane and out-of-plane vascular access skill with 3D visualization over multiple attempts. The training session enables more than half of novices to approach expert performance benchmarks.

HoloLens in suturing training.

PURPOSE: A training module for basic suturing training called Suture Tutor was developed by combining video instruction and voice commands with the Microsoft HoloLens software. We put forth two hypotheses: Trainees find the HoloLens helpful and 2.) HoloLens helps the trainees to achieve a better score in objective skill assessment tests. METHODS: Software module was developed to show instructional video in the HoloLens under voice command. Thirtytwo participants were split into the control group or the HoloLens group. The control group used videos displayed on a computer during training while the HoloLens group practiced with Suture Tutor. Each group was given seven minutes to train with their assigned training method before testing. Testing involved replication of a running locking suturing pattern with a time limit of five minutes and was video recorded. The videos were expert reviewed. Participants in the HoloLens group filled out a usability survey. RESULTS: The trainees found the Hololens to be usable and realistic, and the HoloLens group used the instructional videos more than the control group did (p = 0.0175). There was no difference in the skill assessment test scores between the HoloLens and the control group and their rates of completion in the allotted time was similar. CONCLUSION: Participants found the Suture Tutor to be a user friendly and helpful adjunct. The study was unable to determine if the Suture Tutor helps trainees in achieving a better score in skill assessment testing.

Overall Proficiency Assessment in Point-of-Care Ultrasound Interventions: The Stopwatch is not Enough

With the shift in the medical education curriculum to a competency-based model, objective proficiency assessment is necessary. In this work, we use exploratory factor analysis to assess which primitive metrics convey unique information about proficiency in point-of-care ultrasound applications. We retrospectively validate the proposed methods on three datasets: FAST examination, femoral line, and lumbar puncture. We identify a minimal set of metrics for proficiency assessment in each application. Furthermore, we validate that overall proficiency assessment methods are unaffected by the removal of redundant metrics. This work demonstrates that proficiency in point-of-care ultrasound applications is multi-faceted, and that measuring completion time alone is not enough and application-specific metrics have added value in proficiency assessment.

Training with Perk Tutor improves ultrasound-guided in-plane needle insertion skill

PURPOSE: The open-source Perk Tutor training platform has been shown to improve trainee performance in interventions that require ultrasound guidance. Our goal was to determine if needle coordination of medical trainees can be improved by training with Perk Tutor compared to training with ultrasound only. METHODS: Twenty participants with no previous experience were randomized into two groups; the Perk Tutor group and the Control group. The Perk Tutor group had access to the 3D visualization while the Control group used ultrasound only during their training. Performance was analyzed, measured and compared by Perk Tutor with regards to four needle coordination metrics. None of the groups had access to 3D visualization during performance testing. RESULTS: The needle tracking measurements showed, for the Perk Tutor group, lower average distance between the needle tip and ultrasound (1.2 [0.9 – 2.8] mm vs 2.7 [2.3 – 4.0] mm, respectively; P = 0.023) and lower maximum distance between the needle tip and ultrasound (2.2 [1.9 – 3.2] mm vs 4.6 [3.9 – 6.2] mm, respectively; P = 0.013). There was no significant difference in average needle to ultrasound plane angle and maximum needle to ultrasound plane distance. All participants were successful in the procedure. CONCLUSION: The Perk Tutor group had significantly reduced distance from the needle tip to the ultrasound plane. Training with Perk Tutor can improve trainees’ needle and ultrasound coordination.