Robotic tissue tracking for beating heart mitral valve surgery

Novel Robotic Approach for Minimally Invasive Aortic Heart Valve Surgery

Aortic heart valve replacement is a major surgical intervention, traditionally requiring a large thoracotomy. However, current advances in Minimally Invasive Surgery and Surgical Robotics can offer the possibility to perform the intervention through a narrow mini thoracotomy. The presented surgical robot and proposed surgical scenario aims to provide a highly controllable means for efficiently conducting valve replacement by endoscopic vision. The robot, consisting of a series of joints, is a cable actuated manipulator for reaching the operative site and delivering the valve at the required position. The robot is equipped with endoscopic cameras (to find the hinge points) and three stabilizing flaps (to stabilize the manipulator) for guarantying the proper valve placement. The manipulator is validated by experimental results of flaps' force and camera visions in artificial vessels.

Reflections on ultrasound image analysis

Ultrasound (US) image analysis has advanced considerably in twenty years. Progress in ultrasound image analysis has always been fundamental to the advancement of image-guided interventions research due to the real-time acquisition capability of ultrasound and this has remained true over the two decades. But in quantitative ultrasound image analysis - which takes US images and turns them into more meaningful clinical information - thinking has perhaps more fundamentally changed. From roots as a poor cousin to Computed Tomography (CT) and Magnetic Resonance (MR) image analysis, both of which have richer anatomical definition and thus were better suited to the earlier eras of medical image analysis which were dominated by model-based methods, ultrasound image analysis has now entered an exciting new era, assisted by advances in machine learning and the growing clinical and commercial interest in employing low-cost portable ultrasound devices outside traditional hospital-based clinical settings. This short article provides a perspective on this change, and highlights some challenges ahead and potential opportunities in ultrasound image analysis which may both have high impact on healthcare delivery worldwide in the future but may also, perhaps, take the subject further away from CT and MR image analysis research with time.

Cardioscopic Tool-delivery Instrument for Beating-heart Surgery

This paper describes an instrument that provides solutions to two open challenges in beating-heart intracardiac surgery - providing high-fidelity imaging of tool-tissue contact and controlling tool penetration into tissue over the cardiac cycle. Tool delivery is illustrated in the context of tissue removal for which these challenges equate to visualization of the tissue as it is being removed and to control of cutting depth. Cardioscopic imaging is provided by a camera and illumination system encased in an optical window. When the optical window is pressed against tissue, it displaces the blood between the camera and tissue allowing clear visualization. Control of cutting depth is achieved via precise extension of the cutting tool from a port in the optical window. Successful tool use is demonstrated in ex vivo and in vivo experiments.

Towards active tracking of beating heart motion in the presence of arrhythmia for robotic assisted beating heart surgery

In robotic assisted beating heart surgery, the control architecture for heart motion tracking has stringent requirements in terms of bandwidth of the motion that needs to be tracked. In order to achieve sufficient tracking accuracy, feed-forward control algorithms, which rely on estimations of upcoming heart motion, have been proposed in the literature. However, performance of these feed-forward motion control algorithms under heart rhythm variations is an important concern. In their past work, the authors have demonstrated the effectiveness of a receding horizon model predictive control-based algorithm, which used generalized adaptive predictors, under constant and slowly varying heart rate conditions. This paper extends these studies to the case when the heart motion statistics change abruptly and significantly, such as during arrhythmias. A feasibility study is carried out to assess the motion tracking capabilities of the adaptive algorithms in the occurrence of arrhythmia during beating heart surgery. Specifically, the tracking performance of the algorithms is evaluated on prerecorded motion data, which is collected in vivo and includes heart rhythm irregularities. The algorithms are tested using both simulations and bench experiments on a three degree-of-freedom robotic test bed. They are also compared with a position-plus-derivative controller as well as a receding horizon model predictive controller that employs an extended Kalman filter algorithm for predicting future heart motion.

Visual servoing in medical robotics: a survey. Part II: tomographic imaging modalities--techniques and applications

BACKGROUND

Intraoperative application of tomographic imaging techniques provides a means of visual servoing for objects beneath the surface of organs.

METHODS

The focus of this survey is on therapeutic and diagnostic medical applications where tomographic imaging is used in visual servoing. To this end, a comprehensive search of the electronic databases was completed for the period 2000-2013.

RESULTS

Existing techniques and products are categorized and studied, based on the imaging modality and their medical applications. This part complements Part I of the survey, which covers visual servoing techniques using endoscopic imaging and direct vision.

CONCLUSION

The main challenges in using visual servoing based on tomographic images have been identified. 'Supervised automation of medical robotics' is found to be a major trend in this field and ultrasound is the most commonly used tomographic modality for visual servoing.

Robotic catheter cardiac ablation combining ultrasound guidance and force control

Cardiac catheters allow physicians to access the inside of the heart and perform therapeutic interventions without stopping the heart or opening the chest. However, conventional manual and actuated cardiac catheters are currently unable to precisely track and manipulate the intracardiac tissue structures because of the fast tissue motion and potential for applying damaging forces. This paper addresses these challenges by proposing and implementing a robotic catheter system that uses 3D ultrasound image guidance and force control to enable constant contact with a moving target surface in order to perform interventional procedures, such as intracardiac tissue ablation. The robotic catheter system, consisting of a catheter module, ablation and force sensing end effector, drive system, and image-guidance and control system, was commanded to apply a constant force against a moving target using a position-modulated force control method. The control system uses a combination of position tracking, force feedback, and friction and backlash compensation to achieve accurate and safe catheter–tissue interactions. The catheter was able to maintain a 1 N force on a moving motion simulator target under ultrasound guidance with 0.08 N RMS error. In a simulated ablation experiment, the robotic catheter was also able to apply a consistent force on the target while maintaining ablation electrode contact with 97% less RMS contact resistance variation than a passive mechanical equivalent. In addition, the use of force control improved catheter motion tracking by approximately 20%. These results demonstrate that 3D ultrasound guidance and force tracking allow the robotic system to maintain improved contact with a moving tissue structure, thus allowing for more accurate and repeatable cardiac procedures.

Position Control of Motion Compensation Cardiac Catheters

Robotic catheters have the potential to revolutionize cardiac surgery by enabling minimally invasive structural repairs within the beating heart. This paper presents an actuated catheter system that compensates for the fast motion of cardiac tissue using 3D ultrasound image guidance. We describe the design and operation of the mechanical drive system and catheter module and analyze the catheter performance limitations of friction and backlash in detail. To mitigate these limitations, we propose and evaluate mechanical and control system compensation methods, including inverse and model-based backlash compensation, to improve the system performance. Finally, in vivo results are presented that demonstrate that the catheter can track the cardiac tissue motion with less than 1 mm RMS error. The ultimate goal of this research is to create a fast and dexterous robotic catheter system that can perform surgery on the delicate structures inside of the beating heart.

Ultrasonic image analysis and image-guided interventions

The fields of medical image analysis and computer-aided interventions deal with reducing the large volume of digital images (X-ray, computed tomography, magnetic resonance imaging (MRI), positron emission tomography and ultrasound (US)) to more meaningful clinical information using software algorithms. US is a core imaging modality employed in these areas, both in its own right and used in conjunction with the other imaging modalities. It is receiving increased interest owing to the recent introduction of three-dimensional US, significant improvements in US image quality, and better understanding of how to design algorithms which exploit the unique strengths and properties of this real-time imaging modality. This article reviews the current state of art in US image analysis and its application in image-guided interventions. The article concludes by giving a perspective from clinical cardiology which is one of the most advanced areas of clinical application of US image analysis and describing some probable future trends in this important area of ultrasonic imaging research.