Erol Yeniaras

Collaborative tracking for MRI-guided robotic intervention on the beating heart

Magnetic Resonance Imaging (MRI)-guided robotic interventions for aortic valve repair promise to dramatically reduce time and cost of operations when compared to endoscopically guided (EG) procedures. A challenging issue is real-time and robust tracking of anatomical landmark points. The interventional tool should be constantly adjusted via a closed feedback control loop to avoid harming these points while valve repair is taking place in the beating heart. A Bayesian network of particle filter trackers proves capable to produce real-time, yet robust behavior. The algorithm is extremely flexible and general--more sophisticated behaviors can be produced by simply increasing the cardinality of the tracking network. Experimental results on 16 MRI cine sequences highlight the promise of the method.

MR-based real time path planning for cardiac operations with transapical access

Minimally invasive surgeries (MIS) have been perpetually evolving due to their potential high impact on improving patient management and overall cost effectiveness. Currently, MIS are further strengthened by the incorporation of magnetic resonance imaging (MRI) for amended visualization and high precision. Motivated by the fact that real-time MRI is emerging as a feasible modality especially for guiding interventions and surgeries in the beating heart; in this paper we introduce a real-time path planning algorithm for intracardiac procedures. Our approach creates a volumetric safety zone inside a beating heart and updates it on-the-fly using real-time MRI during the deployment of a robotic device. In order to prove the concept and assess the feasibility of the introduced method, a realistic operational scenario of transapical aortic valve replacement in a beating heart is chosen as the virtual case study.

Towards a new cyber-physical system for MRI-guided and robot-assisted cardiac procedures

Image-guided and robot-assisted minimally invasive surgical procedures are rapidly evolving due to their improved patient management and potential cost effectiveness. Currently, robot-assisted intracardiac surgeries on the beating heart are still in their infancy due to the challenges associated with the dynamic environment of operation. An approach to address those challenges is the use of Magnetic Resonance Imaging (MRI) for preoperative planning as well as for real-time intraoperative guidance. The objective of this paper is to propose a novel cyber-physical system for planning and performing robot-assisted MRI guided interventions in the beating heart with particular focus on aortic valve implantations. Our ongoing research focuses on developing a computational core for MRI-based preoperative planning and generation of dynamic robot maneuvering trajectories, real-time tissue tracking, and a novel MR-compatible robotic manipulator for transapical access to the beating heart.

A novel virtual reality environment for preoperative planning and simulation of image guided intracardiac surgeries with robotic manipulators.

The evolution of image-guided and robot-assisted procedures can be beneficial to intracardiac interventions. This paper proposes a novel approach and a virtual reality system for preoperative planning and intraoperative guidance of cardiac procedures, and for investigating the kinematics and control of a virtual robotic manipulator, based on MRI CINE images. The system incorporates dedicated software modules for processing MR images, generating dynamic trajectories in the continuously changing environment of a beating heart, controlling a specific generic virtual manipulator along those trajectories, and a virtual reality interface that fuses all those information. The proposed system is applied for the simulation of accessing the aortic valve annulus via a small incision on the apex by maneuvering a robotic manipulator through an access corridor that safely transverses the left ventricle (LV) of the beating heart.

Generation of 4d access corridors from real-time multislice MRI for guiding transapical aortic valvuloplasties

Real-time image-guided cardiac procedures (manual or robot-assisted) are emerging due to potential improvement in patient management and reduction in the overall cost. These minimally invasive procedures require both real-time visualization and guidance for maneuvering an interventional tool safely inside the dynamic environment of a heart. In this work, we propose an approach to generate dynamic 4D access corridors from the apex to the aortic annulus for performing real-time MRI guided transapical valvuloplasties. Ultrafast MR images (collected every 49.3 ms) are processed on-the-fly using projections to extract a conservative dynamic trace in form of a three-dimensional access corridor. Our experimental results show that the reconstructed corridors can be refreshed with a delay of less than 0.5ms to reflect the changes inside the left ventricle caused by breathing motion and the heartbeat.

Magnetic resonance based control of a robotic manipulator for interventions in the beating heart

As a part of an ongoing project, in this paper we introduce the first version of a system which has a novel methodology for Cine (as in cinema) MRI based control of a cardiac robot for beating heart surgeries. The system uses the preoperative planning approach that we developed earlier, and integrates it to the intraoperative algorithms for controlling a robot and tracking some specific landmarks of a highly dynamical surgical field. In particular, our late studies presented herein aim to demonstrate the feasibility of integrating appropriate computational tools to achieve the volumetric image guidance for minimally invasive surgeries in the beating heart. We conceive of the system as practicable for in vitro experiments upon the completion of the first physical prototype, which may pave the way for expansion of the approach for other complex surgeries as well.

Design of an actuated phantom to mimic the motion of cardiac landmarks for the study of image-guided intracardiac interventions

In order to be accepted by the clinical and technical community, a new medical tool needs a long duration of testing and validation period. Whereas animal trials are the current standard for evaluating new technologies just before experimenting on human, they are costly in terms of both money and time. For the early stages of a novel technological tool or an approach, the use of a cost-effective and reusable dynamic model would be highly effective. In this study we demonstrate the viability of a novel and specific MR compatible, computer controlled, and actuated phantom that can mimic the left ventricle (LV) for image guided and robot assisted transapical intracardiac surgeries in the beating heart.

Extracting geometric features of aortic valve annulus motion from dynamic MRI for guiding interventions

Transcatheter aortic valve implant (TAVI) has emerged as a prominent approach for treating aortic stenosis. Success of such implants depends upon the accurate assessment of the geometric features such as the diameter, center and orientation of the aortic valve annulus (AVA). In this paper, we present a method for extracting these geometric features from magnetic resonance images (MRI). The method is based on finding an optimal fit for a circular ring mimicking AVA in the aortic root. Moreover, the presented approach provides dynamic tracking of the AVA in CINE MR images. This approach can be used for preoperative planning of prosthetic valve implantation, as well as for the emerging MRI guided manual, or with robot-assisted, annuloplasty.

Noise Sensitive Trajectory Planning for MR Guided TAVI

Image-guided, pre-operative planning is fast becoming the gold standard for navigating real-time robotic cardiac surgeries. Planning helps the surgeon utilize the amended quantitative information of the target area and assess the suitability of the offered intervention technique prior to surgery. In apex access aortic valve replacements, safe zone generation for the penetration of delivery module along the left ventricle (LV) is a crucial step to prevent untoward cases from emerging. To address this problem, we propose a computational core, which is to locate left ventricle borders and specifically papillary muscles (PM), create an obstacle map along the left ventricle (LV), and ultimately extract a dynamic (off-line) trajectory for tool navigation. To this end, we first applied an isotropic diffusion on short-axis (SA) cardiac magnetic resonance (CMR) images. Second, we utilized an active contour model to determine the LV border. Third, we clustered the LV crops to locate the PM. Finally, we computed the centroids of each of the LV segments to determine the safest path for an aortic delivery module.

Robot-Assisted Procedures with MRI Guidance

Real-time image guidance will eventually facilitate a paradigm shift from the traditional endoscopic visualization to one that uses a volumetric and information-rich perception of the area-of-operation, thereby enabling a wider range and level of complexity in minimally invasive surgeries. This chapter will review the use of robotic systems guided by MRI in facilitating image guided robotic-guided interventions.