Eftychios G. Christoforou

A Prototype Manipulator for Magnetic Resonance-Guided Interventions Inside Standard Cylindrical Magnetic Resonance Imaging Scanners

The aim of this work is to develop a remotely controlled manipulator to perform minimally invasive diagnostic and therapeutic interventions in the abdominal and thoracic cavities, with real-time magnetic resonance imaging (MRI) guidance inside clinical cylindrical MR scanners. The manipulator is composed of a three degree of freedom Cartesian motion system, which resides outside the gantry of the scanner, and serves as the holder and global positioner of a three degree of freedom arm which extends inside the gantry of the scanner At its distal end, the arms end-effector can carry an interventional tool such as a biopsy needle, which can be advanced to a desired depth by means of a seventh degree of freedom. These seven degrees of freedom, provided by the entire assembly, offer extended manipulability to the device and a wide envelope of operation to the user, who can select a trajectory suitable for the procedure. The device is constructed of nonmagnetic and nonconductive fiberglass, and carbon fiber composite materials, to minimize artifacts and distortion on the MR images as well as eliminate effects on its operation from the high magnetic field and the fast switching magnetic field gradients used in MR imaging. A user interface was developed for man-in-the-loop control of the device using real-time MR images. The user interface fuses all sensor signals (MR and manipulator information) in a visualization, planning, and control command environment. Path planning is performed with graphical tools for setting the trajectory of insertion of the interventional tool using multislice and/or three dimensional MR images which are refreshed in real time. The device control is performed with an embedded computer which runs real-time control software. The manipulator compatibility with the MR environment and image-guided operation was tested on a 1.5 T MR scanner.

A General-Purpose MR-Compatible Robotic System

The development of a general-purpose robotic system at the Washington University for performing minimally invasive interventions with real-time MR guidance is reviewed. In this paper, the criteria upon which the system was based, and an overview of its components, the design, and prototyping of the robotic manipulator, its control components and their general integration and logic is presented. The human-machine interface and the practice of performing MR-guided interventions are described. It is concluded that when looking into the cost-effectiveness of MR-compatible systems, one cannot ignore the fact that MRI is among the most expensive imaging modalities to acquire and operate.

Medical telerobotic systems: Current status and future trends

Teleoperated medical robotic systems allow procedures such as surgeries, treatments, and diagnoses to be conducted across short or long distances while utilizing wired and/or wireless communication networks. This study presents a systematic review of the relevant literature between the years 2004 and 2015, focusing on medical teleoperated robotic systems which have witnessed tremendous growth over the examined period. A thorough insight of telerobotics systems discussing design concepts, enabling technologies (namely robotic manipulation, telecommunications, and vision systems), and potential applications in clinical practice is provided, while existing limitations and future trends are also highlighted. A representative paradigm of the short-distance case is the da Vinci Surgical System which is described in order to highlight relevant issues. The long-distance telerobotics concept is exemplified through a case study on diagnostic ultrasound scanning. Moreover, the present review provides a classification into short- and long-distance telerobotic systems, depending on the distance from which they are operated. Telerobotic systems are further categorized with respect to their application field. For the reviewed systems are also examined their engineering characteristics and the employed robotics technology. The current status of the field, its significance, the potential, as well as the challenges that lie ahead are thoroughly discussed.

Fast and efficient radiological interventions via a graphical user interface commanded magnetic resonance compatible robotic device.

The graphical user interface for an MR compatible robotic device has the capability of displaying oblique MR slices in 2D and a 3D virtual environment along with the representation of the robotic arm in order to swiftly complete the intervention. Using the advantages of the MR modality the device saves time and effort, is safer for the medical staff and is more comfortable for the patient

A novel, general-purpose, MR-compatible, manually actuated robotic manipulation system for minimally invasive interventions under direct MRI guidance

Performing minimally invasive interventions under direct MRI guidance offers significant advantages. Required accessibility to the patient inside the MRI scanner is fairly limited, and employment of robotic assistance has been proposed. The development of MR‐compatible robotic systems entails engineering challenges related to geometric constraints and the magnetic nature of the scanning environment.

An Approach for Preoperative Planning and Performance of MR-guided Interventions Demonstrated With a Manual Manipulator in a 1.5T MRI Scanner

PurposeThe aim of this work was to develop and test a general methodology for the planning and performance of robot-assisted, MR-guided interventions. This methodology also includes the employment of software tools with appropriately tailored routines to effectively exploit the capabilities of MRI and address the relevant spatial limitations.MethodsThe described methodology consists of: (1) patient-customized feasibility study that focuses on the geometric limitations imposed by the gantry, the robotic hardware, and interventional tools, as well as the patient; (2) stereotactic preoperative planning for initial positioning of the manipulator and alignment of its end-effector with a selected target; and (3) real-time, intraoperative tool tracking and monitoring of the actual intervention execution. Testing was performed inside a standard 1.5T MRI scanner in which the MR-compatible manipulator is deployed to provide the required access.ResultsA volunteer imaging study demonstrates the application of the feasibility stage. A phantom study on needle targeting is also presented, demonstrating the applicability and effectiveness of the proposed preoperative and intraoperative stages of the methodology. For this purpose, a manually actuated, MR-compatible robotic manipulation system was used to accurately acquire a prescribed target through alternative approaching paths.ConclusionsThe methodology presented and experimentally examined allows the effective performance of MR-guided interventions. It is suitable for, but not restricted to, needle-targeting applications assisted by a robotic manipulation system, which can be deployed inside a cylindrical scanner to provide the required access to the patient facilitating real-time guidance and monitoring.

Motion Planning for Shape–Controlled Adaptable Buildings Resembling Topologically Closed–Loop Robotic Systems

Shape–controlled adaptable building structures have a potential of superior performance and flexibility compared to traditional fixed–shape ones. A building concept is proposed consisting of a number of interconnected planar n–bar linkages performing coordinated motions thus resembling a system of cooperating closed–loop robotic manipulators. For shape control an “effective 4–bar” linkage concept is proposed. That is, each individual n–bar mechanism is equipped with one motion actuator, and at any time of motion its degrees–of–freedom are reduced to one through the selective locking of (n – 4) joints using brakes. Shape adjustments of the overall structure can be carried out through appropriate control sequences where in each step exactly four joints of each linkage are unlocked giving rise to an effective 4–bar system. Motion planning is considered together with the relevant limitations arising from singular configurations that need to be taken into account. The concept is demonstrated through simulation examples.Copyright

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.

Consideration of geometric constraints regarding MR-compatible interventional robotic devices

The design of MR-compatible robotic systems is a challenging task given the magnetic nature of the scanning environment but also the limitations imposed by the geometric characteristics of the imaging modality. The latter issue is often referred to as geometric MR-compatibility and was treated through image-based analyses as part of the design of a new interventional robotic device. Examinations on geometric MR-compatibility focused on ways to quantify the available space inside a cylindrical scanner, considerations regarding the effective field-of-view of an MR scanner, representations of the attainable anatomical region as defined for needle targeting applications, and computer simulations using three-dimensional digital models representing the patient. Geometric considerations are relevant both to the design of an MR-compatible robotic device but also its operation, as for example when using patient-specific data for intervention planning purposes. A preoperative planning procedure developed for the new robotic device will also be described.

TOWARDS REALIZATION OF SHAPE-CONTROLLED ADAPTABLE BUILDINGS FOLLOWING A ROBOTICS APPROACH

Shape‐controlled adaptable buildings constitute a major excursion from traditional architectural approaches with a potential for superior performance and enhanced flexibility compared to traditional fixed‐shape building structures. A building concept is examined whose skeleton structure consists of a parallel arrangement of planar closed‐loop n‐bar linkages and it is covered with a flexible material. Shape adjustments involve coordinated reconfigurations of the constituent closed‐chain mechanisms. Each individual linkage is equipped with one motion actuator as well as brakes installed on every joint. For the reconfigurations an “effective 4‐bar” concept has been proposed that involves stepwise adjustments. Each step involves the selective locking of (n 4) joints of each linkage so that it is effectively reduced to a single‐DOF 4‐bar mechanism the configuration of which can be adjusted using the available motion actuator. Appropriately planned control sequences can be used for a complete reconfiguration of the linkage. Motion planning is concerned with the generation of optimal control sequences while taking into account imposed limitations arising from the moving structure as well as the flexible envelop. This paper is a continuation of a prior work paying special attention to the envelop design. Simulation examples as well as an experimental study are used to demonstrate the feasibility of the concept and investigate relevant issues.