Mixed reality holograms for heart surgery planning: first user experience in congenital heart disease.

AIMS: Proof of concept and feasibility study for preoperative diagnostic use of mixed reality (MR) holograms of individual 3D heart models from standard cardiac computed tomography angiograms (CTA) images. Optimal repair for complex congenital heart disease poses high demands on 3D anatomical imagination. Three-dimensional printed heart models are increasingly used for improved morphological understanding during surgical and interventional planning. Holograms are a dynamic and interactive alternative, probably with wider applications. METHODS AND RESULTS: A 3D heart model was segmented from CTA images in a patient with double outlet right ventricle and transposition of the great arteries (DORV-TGA). The hologram was visualized in the wearable MR platform HoloLens® for 36 paediatric heart team members who filled out a diagnostic and quality rating questionnaire. Morphological and diagnostic output from the hologram was assessed and the 3D experience was evaluated. Locally developed app tools such as hologram rotation, scaling, and cutting were rated. Anatomy identification and diagnostic output was high as well as rating of 3D experience. Younger and female users rated the app tools higher. CONCLUSION: This preliminary study demonstrates that MR holograms as surgical planning tool for congenital heart disease may have a high diagnostic value and contribute to understanding complex morphology. The first users experience of the hologram presentation was found to be very positive, with a preference among the female and the younger users. There is potential for improvement of the hologram manipulation tools.

Edge density based automatic detection of inflammation in colonoscopy videos.

Colon cancer is one of the deadliest diseases where early detection can prolong life and can increase the survival rates. The early stage disease is typically associated with polyps and mucosa inflammation. The often used diagnostic tools rely on high quality videos obtained from colonoscopy or capsule endoscope. The state-of-the-art image processing techniques of video analysis for automatic detection of anomalies use statistical and neural network methods. In this paper, we investigated a simple alternative model-based approach using texture analysis. The method can easily be implemented in parallel processing mode for real-time applications. A characteristic texture of inflamed tissue is used to distinguish between inflammatory and healthy tissues, where an appropriate filter kernel was proposed and implemented to efficiently detect this specific texture. The basic method is further improved to eliminate the effect of blood vessels present in the lower part of the descending colon. Both approaches of the proposed method were described in detail and tested in two different computer experiments. Our results show that the inflammatory region can be detected in real-time with an accuracy of over 84%. Furthermore, the experimental study showed that it is possible to detect certain segments of video frames containing inflammations with the detection accuracy above 90%.

The Effect of Interaction Force Estimation on Performance in Bilateral Teleoperation.

Measuring interaction forces in bilateral teleoperation systems may be difficult, due to size and cost restrictions on the force sensors. Obtaining the interaction forces by estimation can be a viable alternative. The primary contribution of this paper is the study of the effect of interaction force estimation on performance in bilateral teleoperation. A distinction is made between the obvious effect as a result of inaccurate estimation, and the less obvious effect as a result of the inherent theoretical properties of a system that has two points of interaction with its surroundings (a teleoperator) as opposed to one point of interaction (single robot). Specifically, the existence of a singularity property is pointed out, at which interaction force estimation is impossible, and close to which it may be infeasible. The secondary contribution of the paper is the Force Sensor Free (FSF) transformation for linear teleoperation systems, which is an automated procedure that turns a teleoperation controller with force sensing into an equivalent controller with force estimation. An experiment is reported whose objective is to validate the operation of the FSF transformation on a real teleoperator.

Detection of myocardial ischaemia by epicardial accelerometers in the pig.

BACKGROUND: We describe a novel technique for continuous real-time assessment of myocardial ischaemia using a three-axis accelerometer. METHODS: In 14 anaesthetized open-chest pigs, two accelerometers were sutured on the left ventricle (LV) surface in the perfusion areas of the left anterior descending (LAD) and circumflex (CX) arteries. Acceleration was measured in the longitudinal, circumferential, and radial directions, and the corresponding epicardial velocities were calculated. Regional LV dysfunction was induced by LAD occlusion for 60 s. Global LV function was altered by nitroprusside, epinephrine, esmolol, and fluid loading. Epicardial velocities were compared with strain by echocardiography during LAD occlusion and with aortic flow and LV dP/dt(max) during interventions on global LV function. RESULTS: LAD occlusion induced ischaemia, shown by lengthening in systolic strain in the LV apical anterior region (P<0.01) and concurrent changes in LAD accelerometer circumferential velocities during systole (P<0.01) and during the isovolumic relaxation phase (P<0.01). The changes in accelerometer circumferential velocities during LAD occlusion were greater compared with the changes during the interventions on global function (P<0.01). For the LAD accelerometer circumferential velocities, sensitivity was 94-100% and specificity was 92-94% in detecting ischaemia. CONCLUSIONS: Myocardial ischaemia can be detected with epicardial three-axis accelerometers. The accelerometer had the ability to distinguish ischaemia from interventions altering global myocardial function. This novel technique may be used for continuous real-time monitoring of myocardial ischaemia during and after cardiac surgery.

Virtual reality simulator training equals mechanical robotic training in improving robot-assisted basic suturing skills.

BACKGROUND: This study aimed to investigate the effect of a virtual reality simulator on the learning of basic robotic suturing skills. METHODS: Two randomized groups of students underwent a controlled training program. Both groups completed an identical test before and after training. The increase in the number of stitches placed during the pretest and posttest was used as an objective measure of the training effect. To evaluate the subjective feeling of understanding and mastering, the students indicated this on a visual analog scale. RESULTS: Both groups showed a significant increase in the number of stitches placed during the posttest, and an increase in subjective feeling of understanding and mastering. The increase did not differ between the groups, indicating that the virtual reality simulator equaled the mechanical trainer in training of robotic suturing technique. CONCLUSIONS: Training in basic robot-assisted suturing skills using a virtual reality simulator without additional training equaled training using a mechanical simulator.

Measurements of heart motion using accelerometers.

We have used acceleration sensors to monitor the heart motion during surgery. A three-axis accelerometer was made from two commercially available two-axis sensors, and was used to measure the heart motion in anesthetized pigs. The heart moves due to both respiration and heart beating. The heart beating was isolated from respiration by high-pass filtering at 1.0 Hz, and heart wall velocity and position were calculated by numerically integrating the filtered acceleration traces. The resulting curves reproduced the heart motion in great detail, noise was hardly visible. Events that occurred during the measurements, e.g. arrhythmias and fibrillation, were recognized in the curves, and confirmed by comparison with synchronously recorded ECG data. We conclude that acceleration sensors are able to measure heart motion with good resolution, and that such measurements can reveal patterns that may be an indication of heart circulation failure.

Digital trainer developed for robotic assisted cardiac surgery.

Robotic systems for cardiac surgery have been introduced in clinical trials to facilitate minimally invasive techniques. Widespread use of surgical robotics necessitates new training methods to improve skills and continue practicing as the robotic systems are frequently being upgraded. Today, robotic training is performed on expensive animal models. An integration of a digital trainer with the two present robotic systems applied in coronary artery bypass procedures on beating heart requires real time simulation of tissue mechanics, sutures, instruments and bleeding. However, it requires no extra haptic device, since the robotic master is the haptic apparatus itself. By developing new data structures and parametric geometry descriptions we have demonstrated the possibility of obtaining surgical simulation on a standard PC Linux system. This technology is beneficial when simulation is exploited over a network with limited bandwidth, especially when it comes to the handling of soft tissue dynamics.

[Image guided and robotic treatment--the advance of cybernetics in clinical medicine]. / Bildeveiledet og robotisert behandling--kybernetikkens inntog i klinisk medisin.

The introduction of advanced technology in hospitals has changed the treatment practice towards more image guided and minimal invasive procedures. Modern computer and communication technology opens up for robot aided and pre-programmed intervention. Several robotic systems are in clinical use today both in microsurgery and in major cardiac and orthopedic operations. As this trend develops, professions which are new in this context such as physicists, mathematicians and cybernetic engineers will be increasingly important in the treatment of patients.