Background
●Simulation-based training is increasingly important in competency-based medical education because it allows trainees to build technical skill, judgment, and procedural confidence in a controlled environment before entering the operating room [1].
●Minimally invasive mitral valve repair depends on an endoscopic view, so surgeons must interpret anatomy, depth, tissue appearance, and instrument interactions through the camera rather than direct visualization.
●Silicone mitral valve phantoms are practical for simulation-based training, but their visual appearance differs substantially from the intraoperative field.
●This mismatch may limit trainee immersion and reduce transfer of visual-anatomical skills from the simulator to the operating room.
●Prior work by Engelhardt et al. [2] showed that hyperrealistic image translation can improve mitral valve training phantoms, motivating further work on realism and temporal stability.
Aim
●Develop and validate a surgically relevant image dataset and neural image translation framework to improve the visual realism of mitral valve training phantoms.
●Better replicate the live operative appearance of minimally invasive mitral valve surgery.
●Evaluate both perceptual realism and temporal stability, since useful simulation must support continuous endoscopic viewing rather than isolated still images.
Methods
●Collected endoscopic video data from minimally invasive mitral valve repair procedures and from silicone mitral valve phantoms positioned to match operative viewing angles.
●Curated 59,411 surgical frames from 570 surgical videos and 6,625 phantom frames from the simulator domain.
●Compared unpaired image-to-image translation models including CycleGAN, MUNIT, and DRIT [3].
●Tested patch-based consistency constraints to reduce frame-to-frame flickering during video playback.
●Evaluated perceptual similarity and temporal consistency in both static images and dynamic video sequences
Dataaset and Workflow
●We built a surgical image dataset that captures clinically relevant mitral anatomy, endoscopic lighting conditions, tissue appearance, and instrument interactions seen during minimally invasive repair.
●Phantom images were collected under endoscopic viewpoints chosen to resemble the depth, angle, and field of view seen in the real surgical videos.
●Neural image translation was then applied to convert visually simple phantom images into outputs that more closely resembled the live operative field.
Results
●Image translation improved phantom realism by adding more representative tissue texture, coloration, lighting effects, and instrument context to the simulator.
●Standard style translation produced acceptable realism in static images, but greater visual detail in video sequences was associated with increased frame-to-frame flickering, indicating a trade-off between realism and stability.
●Incorporating temporal consistency constraints reduced flicker and improved output stability while maintaining realism, supporting more continuous and usable endoscopic visualization for training.
●Increasing dataset size was associated with improved image fidelity and better visual continuity across adjacent frames in the translated sequences.
●Image translation improved phantom realism, adding tissue coloration, specular highlights, and more operative-looking visual context.
●Best perceptual realism was achieved by MUNITImgNet, with perceptual similarity (FID) score 16.3 ± 3.2 versus 79.7 ± 17.9 for baseline simulator images.
●CycleGANPatch improved both realism and stability, reducing FID from 42.7 ± 9.1 to 30.2 ± 4.5 while also improving temporal consistency.
●Overall, lower FID scores generally came with greater frame-to-frame variation, highlighting a realism-versus-stability trade-off relevant to video-based simulation.
Conclusions
●AI-based image translation can narrow the visual gap between silicone mitral valve phantoms and the live operative field.
●For clinical simulation, photorealism alone is not enough; stable video output is also required for continuous endoscopic training.
●These findings support integration of image translation into next-generation minimally invasive and robotic mitral simulation platforms.
●Future work will focus on surgeon validation, trainee performance studies, and improved temporally consistent models for real-time deployment.