Navigation accuracy for an intracardiac procedure using ultrasound enhanced virtual reality

Abstract

Minimally invasive techniques for use inside the beating heart, such as mitral valve replacement and septal defect repair, are the focus of this work. Traditional techniques for these procedures require an open chest approach and a cardiopulmonary bypass machine. New techniques using port access and a combined surgical guidance tool that includes an overlaid two-dimensional ultrasound image in a virtual reality environment are being developed. To test this technique, a cardiac phantom was developed to simulate the anatomy. The phantom consists of an acrylic box filled with a 7% glycerol solution with ultrasound properties similar to human tissue. Plate inserts mounted in the box simulate the physical anatomy. An accuracy assessment was completed to evaluate the performance of the system.Using the cardiac phantom, a 2mm diameter glass toroid was attached to a vertical plate as the target location. An elastic material was placed between the target and plate to simulate the target lying on a soft tissue structure. The target was measured using an independent measurement system and was represented as a sphere in the virtual reality system. The goal was to test the ability of a user to probe the target using three guidance methods: (i) 2D ultrasound only, (ii) virtual reality only and (iii) ultrasound enhanced virtual reality. Three users attempted the task three times each for each method. An independent measurement system was used to validate the measurement. The ultrasound imaging alone was poor in locating the target (5.42 mm RMS) while the other methods proved to be significantly better (1.02 mm RMS and 1.47 mm RMS respectively). The ultrasound enhancement is expected to be more useful in a dynamic environment where the system registration may be disturbed.

Virtual reality-enhanced ultrasound guidance: A novel technique for intracardiac interventions

“…The additional errors with ''VR þ US'' were attributed to the quality of the US images acquired with the trans-esophageal probe. It is anticipated that ''VR þ US'' will provide a superior solution when used in a dynamic environment such as an actual in vivo intracardiac procedure [29].…”

The Use of Ultrasound to Guide Interventions: From Bench to Bedside and Back Again

“…We have used 2D ultrasound as the sole navigation platform, 3D ultrasound as the sole navigation platform, and a combination of both recognizing some of the inherent limitations with each modality. [12][13][14][15][16][17][18][19][20][21] We have also adopted visualization with an enhanced reality platform tracking within a magnetic field to improve minimal access procedures within the heart. These same systems have also been adapted to perform interventions on the lumbar vertebrae.…”

Towards Subject-Specific Models of the Dynamic Heart for Image-Guided Mitral Valve Surgery

“…According to our collaborating cardiac surgeon, a misalignment on the order of approximately 5 mm is tolerable, as these models will be used to facilitate the navigation of instruments towards the surgical targets, whereas on-target positioning and fine tuning will be performed under real-time US guidance. In addition, the relative accuracy of the tracked surgical tools is on the order of 1-2 mm [14], leading to an accurate virtual tool to US navigation.…”