A validated subjective rating of display quality: The Maryland Visual Comfort Scale (original) (raw)
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Characterizing the ?gold standard? image for laparoscopic surgery
Surgical Endoscopy, 2004
Background: The term ''gold standard'' is often used to describe preferred display devices, frequently without substantiating evidence. A meaningful and objective measure of display quality for endoscopic surgery is required. Methods: Typical colors from five tissue types were arranged in a striped pattern and displayed on four devices: a medical-grade cathode ray tube monitor, a liquid crystal display, a digital light projection display, and an obsolete cathode ray tube (CRT) monitor. The breadth and color contrast of the stripes were adjusted until the patterns became indiscernible to 12 subjects. The data provide a discernibility threshold. Results: The liquid crystal display (LCD) monitor provided the best image. The medical grade and obsolete CRTs were second and third, respectively, and the projection display provided the most inferior image. Conclusions: A meaningful and relevant measurement of image display quality for laparoscopic surgery based on the discernibility threshold is provided. Of the devices tested, the LCD is the best in terms of image, although the CRT may be preferred at off-axis viewing angles. The projection system, however, offers compensatory ergonomic advantages.
Surgical Endoscopy, 2010
Background Surgeons performing laparoscopic surgery have strong biases regarding the quality and nature of the laparoscopic video monitor display. In a comparative study, we used a unique computerized sensing and analysis system to evaluate the various types of monitors employed in laparoscopic surgery. Methods We compared the impact of different types of monitor displays on an individual's performance of a laparoscopic training task which required the subject to move the instrument to a set of targets. Participants (varying from no laparoscopic experience to board-certified surgeons) were asked to perform the assigned task while using all three display systems, which were randomly assigned: a conventional laparoscopic monitor system (2D), a highdefinition monitor system (HD), and a stereoscopic display (3D). The effects of monitor system on various performance parameters (total time consumed to finish the task, average speed, and movement economy) were analyzed by computer. Each of the subjects filled out a subjective questionnaire at the end of their training session. Results A total of 27 participants completed our study. Performance with the HD monitor was significantly slower than with either the 3D or 2D monitor (p \ 0.0001). Movement economy with the HD monitor was significantly reduced compared with the 3D (p \ 0.0004) or 2D
2018
Background: Three-dimensional (3D) stereoscopic vision is crucial to perform any kind of manual tasks. The reduction from real life 3D- to virtual two-dimensional (2D) sight is a major challenge in minimal invasive surgery (MIS). 3D-display technique has shown to reduce operation time, mistakes, and improve the learning curve. Therefore it seems to optimize surgical performance for novice and experienced surgeons. Inspired by consumer electronics 4K display technique was introduced to MIS recently. Due to its high resolution and zoom-effect surgeons should benefit from it. Aim of this study is to evaluate if “state-of-the-art” 3D- versus 4K- display techniques could influence surgical performance. Methods: A randomized cross-over single-institution single-blinded trial is designed. It compares the primary outcome parameter “surgical performance”, represented by “performance time “ and “number of mistakes” using a passive polarizing 3D- and a 4K-display system (2 arms) to perform dif...
Trials, 2019
Background: Three-dimensional (3D) stereoscopic vision is crucial to perform any kind of manual task. The reduction from real life 3D to virtual two-dimensional (2D) sight is a major challenge in minimally invasive surgery (MIS). A 3D display technique has been shown to reduce operation time and mistakes and to improve the learning curve. Therefore, the use of a3D display technique seems to optimize surgical performance for novice and experienced surgeons. Inspired by consumer electronics, a 4K display technique was recently introduced to MIS. Due to its high resolution and zoom effect, surgeons should benefit from it. The aim of this study is to evaluate if "state-of-the-art" 3D-vs. 4K-display techniques could influence surgical performance. Methods: A randomized, cross-over, single-institution, single-blinded trial is designed. It compares the primary outcome parameter "surgical performance", represented by "performance time "and "number of mistakes", using a passive polarizing 3D and a 4K display system (two arms) to perform different tasks in a minimally invasive/laparoscopic training parkour. Secondary outcome parameters are the mental stress load (National Aeronautics and Space Administration (NASA) Task Load Index) and the learning curve. Unexperienced novices (medical students), non-board-certified, and board-certified abdominal surgeons participate in the trial (i.e., level of experience, 3 strata). The parkour consists of seven tasks (for novices, five tasks), which will be repeated three times. The 1st run of the parkour will be performed with the randomized display system, the 2nd run with the other one. After each run, the mental stress load is measured. After completion of the parkour, all participants are evaluated by an ophthalmologist for visual acuity and stereoscopic vision with five tests. Assuming a correlation of 0.5 between measurements per subject, a sample size of 36 per stratum is required to detect a standardized effect of 0.5 (including an additional 5% for a non-parametric approach) with a power of 80% at a two-sided type I error of 5%. Thus, altogether 108 subjects need to be enrolled.
Ongoing advances in video processing are bringing the digital revolution to the operating room, giving rise to new opportunities such as tele-surgery and tele-collaboration. Applications such as minimally invasive and robotic surgery generate large video streams that demand gigabytes of storage and transmission capacity. While lossy data compression can offer large size reduction, excessively high compression levels may reduce image quality to clinically unacceptable levels. In this study we assess the quality of compressed laparoscopic video using a subjective evaluation study and state-of-the-art objective measures. Test sequences were full High-Definition videos captures of four laparoscopic surgery procedures acquired on two camera types. Raw sequences were processed with H.264/AVC IPPP-CBR at four compression levels (19.5, 5.5, 2.8, and 1.8 Mbps) chosen with a pilot study. 16 non-experts and 9 laparoscopic surgeons evaluated the quality and suitability for surgery (surgeons only) using Single Stimulus Continuous Quality Evaluation (SSCQE) methodology. VQM, HDR-VDP-2, and PSNR objective measures were evaluated. The results suggest that laparoscopic video may be lossy compressed by a factor of 30 to 100 (19.5 to 5.5 Mbps) without sacrificing visual quality, potentially enabling real-time streaming of surgical procedures even over wireless networks. Surgeons were sensitive to content but had large variances in quality scores, whereas non-experts judged all scenes similarly and over-estimated the quality of some sequences. There was high correlation between surgeons' scores for quality and "suitability for surgery". The three objective measures had moderate to high correlation with subjective scores, especially when analyzed separately by camera type. .be * Typically, classification tasks -even when conducted by humans -are referred to as objective tasks in medical image quality assessment. However, to avoid confusion, in this paper we use the term objective in the general video quality assessment sense: metrics which assess the appearance or fidelity of the image, and not the performance on a particular clinical task.
Visual quality assessment of H.264/AVC compressed laparoscopic video
Medical Imaging 2014: Image Perception, Observer Performance, and Technology Assessment, 2014
Ongoing advances in video processing are bringing the digital revolution to the operating room, giving rise to new opportunities such as tele-surgery and tele-collaboration. Applications such as minimally invasive and robotic surgery generate large video streams that demand gigabytes of storage and transmission capacity. While lossy data compression can offer large size reduction, excessively high compression levels may reduce image quality to clinically unacceptable levels. In this study we assess the quality of compressed laparoscopic video using a subjective evaluation study and state-of-the-art objective measures. Test sequences were full High-Definition videos captures of four laparoscopic surgery procedures acquired on two camera types. Raw sequences were processed with H.264/AVC IPPP-CBR at four compression levels (19.5, 5.5, 2.8, and 1.8 Mbps) chosen with a pilot study. 16 non-experts and 9 laparoscopic surgeons evaluated the quality and suitability for surgery (surgeons only) using Single Stimulus Continuous Quality Evaluation (SSCQE) methodology. VQM, HDR-VDP-2, and PSNR objective measures were evaluated. The results suggest that laparoscopic video may be lossy compressed by a factor of 30 to 100 (19.5 to 5.5 Mbps) without sacrificing visual quality, potentially enabling real-time streaming of surgical procedures even over wireless networks. Surgeons were sensitive to content but had large variances in quality scores, whereas non-experts judged all scenes similarly and over-estimated the quality of some sequences. There was high correlation between surgeons' scores for quality and "suitability for surgery". The three objective measures had moderate to high correlation with subjective scores, especially when analyzed separately by camera type. .be * Typically, classification tasks -even when conducted by humans -are referred to as objective tasks in medical image quality assessment. However, to avoid confusion, in this paper we use the term objective in the general video quality assessment sense: metrics which assess the appearance or fidelity of the image, and not the performance on a particular clinical task.
Medical image quality as a socio-technical phenomenon
Methods of information in medicine, 2003
The study aims to interpret image quality in laparoscopic surgery not only as a technical parameter but also as the result of the situation of use. Observational studies of laparoscopy in use, semi-structured and informal interviews with laparoscopists. When medical images are digitized to exploit novel technical possibilities, image quality becomes a paramount issue. Image quality is often discussed exclusively in technical terms, but the socio-technical study of image quality in surgical telemedicine presented in this paper showed that it is definitely more than a purely technical parameter. While the resulting quality of the image was significantly shaped by the persons involved, the concept of "quality" itself was also relative and changing with the situation of use. A given technology does not determine image quality. Rather than focusing only on the technical quality, the attention of designers and decision makers should also be directed to the socio-technical networ...
Investigation of the Impact of Compression on the Perceptional Quality of Laparoscopic Videos
2014 IEEE 27th International Symposium on Computer-Based Medical Systems, 2014
In recent years it has become common practice to archive video recordings of laparoscopic surgeries for documentation purposes and for retrospective review. Typically, the videos are captured in High Definition (HD) format but encoded with legacy coding standards like MPEG-2 requiring an enormous storage capacity. In this paper we present the results of a subjective quality assessment study with 37 medical experts. We identify appropriate encoding configurations for the H.264/AVC coding standard to guarantee a visually lossless quality with a significant bitrate reduction. Further, we show that it is not necessary to capture the highest possible quality for documentation and retrospective analysis. A lower technical quality with a substantially lower bitrate still provides sufficient semantic quality. We finally present basic recommendations for an efficient encoding strategy with an appropriate tradeoff between visual quality and bitrate.
Surgical Endoscopy And Other Interventional Techniques, 2002
Background: Compared to open surgery, minimally invasive surgery (MIS) relies heavily on advanced technology, such as endoscopic viewing systems and innovative instruments. The aim of the study was to objectively compare three technologically advanced laparoscopic viewing systems with the standard viewing system currently used in most Dutch hospitals. Methods: We evaluated the following advanced laparoscopic viewing systems: a Thin Film Transistor (TFT) display, a stereo endoscope, and an image projection display. The standard viewing system was comprised of a monocular endoscope and a high-resolution monitor. Task completion time served as the measure of performance. Eight surgeons with laparoscopic experience participated in the experiment. Results: The average task time was signi®cantly greater (p < 0.05) with the stereo viewing system than with the standard viewing system. The average task times with the TFT display and the image projection display did not dier signi®cantly from the standard viewing system. Conclusion: Although the stereo viewing system promises improved depth perception and the TFT and image projection displays are supposed to improve hand±eye coordination, none of these systems provided better task performance than the standard viewing system in this pelvi-trainer experiment.
Comparative study of the methodologies used for subjective medical image quality assessment
Physics in Medicine & Biology, 2021
Healthcare professionals have been increasingly viewing medical images and videos in their routine clinical practice, and this in a wide variety of environments. Both the perception and interpretation of medical visual information, across all branches of practice or medical specialties (e.g., diagnostic, therapeutic, or surgical medicine), career stages, and practice settings (e.g., emergency care), appear to be critical for patient care. However, medical images and videos are not self-explanatory and, therefore, need to be interpreted by humans, i.e., medical experts. In addition, various types of degradations and artifacts may appear during image acquisition or processing, and consequently affect medical imaging data. Such distortions tend to impact viewers' quality of experience, as well as their clinical practice. It is accordingly essential to better understand how medical experts perceive the quality of visual content. Thankfully, progress has been made in the recent literature towards such understanding. In this article, we present an up-to-date state of the art of relatively recent (i.e., not older than ten years old) existing studies on the subjective quality assessment of medical images and videos, as well as research works using task-based approaches. Furthermore, we discuss the merits and drawbacks of the methodologies used, and we provide recommendations about experimental designs and statistical processes to evaluate the perception of medical images and videos for future studies, which could then be used to optimise the visual experience of image readers in real clinical practice. Finally, we tackle the issue of the lack of available annotated medical image and video quality databases, which appear to be indispensable for the development of new dedicated objective metrics.