Needle Steering in 3-D Via Rapid Replanning.

Steerable needles have the potential to improve the effectiveness of needle-based clinical procedures such as biopsy and drug delivery by improving targeting accuracy and reaching previously inaccessible targets that are behind sensitive or impenetrable anatomical regions. We present a new needle steering system capable of automatically reaching targets in 3-D environments while avoiding obstacles and compensating for real-world uncertainties. Given a specification of anatomical obstacles and a clinical target (e.g., from preoperative medical images), our system plans and controls needle motion in a closed-loop fashion under sensory feedback to optimize a clinical metric. We unify planning and control using a new fast algorithm that continuously replans the needle motion. Our rapid replanning approach is enabled by an efficient sampling-based rapidly exploring random tree (RRT) planner that achieves orders-of-magnitude reduction in computation time compared with prior 3-D approaches by incorporating variable curvature kinematics and a novel distance metric for planning. Our system uses an electromagnetic tracking system to sense the state of the needle tip during the procedure. We experimentally evaluate our needle steering system using tissue phantoms and animal tissue ex vivo. We demonstrate that our rapid replanning strategy successfully guides the needle around obstacles to desired 3-D targets with an average error of less than 3 mm.

Debulking from within: a robotic steerable cannula for intracerebral hemorrhage evacuation.

New approaches to intracerebral hemorrhage management are motivated by its high incidence and 40% mortality rate. Surgery is sometimes attempted to decompress the brain, although patient outcomes are similar regardless of whether surgery occurs. We hypothesize that surgical decompression is not more effective because current open surgical techniques disrupt healthy brain tissue to access the clot formed by the hemorrhage, offsetting the benefits of surgery. To address this, we propose a less invasive needle-based approach in which the clot is debulked from within using a superelastic, precurved aspiration cannula that is deployed from a needle. The tip of this aspiration cannula is controlled by coordinated insertion and retraction of the cannula and needle, as well as axial rotation of the cannula. We describe the design of a sterilizable and biocompatible robot that can control the three degrees of freedom of the needle and cannula. Image guidance is achieved by adapting an approach originally developed for brain biopsy. We provide an optimization method for the selection of the precurvatures of one or more sequentially used aspiration cannulas to maximize hemorrhage evacuation, based on preoperative medical image data. In vitro experiments demonstrate the feasibility of evacuating 83-92% of hemorrhage volume, depending on the number of tubes and deployment method used.

Robotic surgery for the sinuses and skull base: what are the possibilities and what are the obstacles?

PURPOSE OF REVIEW: Robotic surgery in otolaryngology - head and neck surgery has become a valuable tool in certain anatomic approaches; however, its application in surgery of the paranasal sinuses and anterior skull base is still in an investigatory phase and requires further evaluation. RECENT FINDINGS: Existing robotic surgical systems face particular limitations in their application at the skull base because of instrument size and lack of variability. Unfortunately, only one system is available commercially that is applicable in the head and neck region and FDA approved for use in patients. This system, although advantageous in many otolaryngologic procedures, is difficult to use for endoscopic sinus and skull base surgery. However, other systems that target this anatomic subsite specifically are in development and show promise. Advances in the design of robotic arms, materials, and shape will potentially give surgeons a significant advantage over traditional endoscopic techniques. SUMMARY: This article will review the current applications of robotic systems in paranasal sinus and skull base surgery, describe the requirements of a robotic system for use in this type of surgery, and describe a system under development at our institution.

A Telerobotic System for Transnasal Surgery.

Mechanics-based models of concentric tube continuum robots have recently achieved a level of sophistication that makes it possible to begin to apply these robots to a variety of real-world clinical scenarios. Endonasal skull base surgery is one such application, where their small diameter and tentacle like dexterity are particularly advantageous. In this paper we provide the medical motivation for an endonasal surgical robot featuring concentric tube manipulators, and describe our model-based design and teleoperation methods, as well as a complete system incorporating image-guidance. Experimental demonstrations using a laparoscopic training task, a cadaver reachability study, and a phantom tumor resection experiment illustrate that both novice and expert users can effectively teleoperate the system, and that skull base surgeons can use the robot to achieve their objectives in a realistic surgical scenario.

Comparison study of intraoperative surface acquisition methods for surgical navigation.

Soft-tissue image-guided interventions often require the digitization of organ surfaces for providing correspondence from medical images to the physical patient in the operating room. In this paper, the effect of several inexpensive surface acquisition techniques on target registration error and surface registration error (SRE) for soft tissue is investigated. A systematic approach is provided to compare image-to-physical registrations using three different methods of organ spatial digitization: 1) a tracked laser-range scanner (LRS), 2) a tracked pointer, and 3) a tracked conoscopic holography sensor (called a conoprobe). For each digitization method, surfaces of phantoms and biological tissues were acquired and registered to CT image volume counterparts. A comparison among these alignments demonstrated that registration errors were statistically smaller with the conoprobe than the tracked pointer and LRS (p<0.01). In all acquisitions, the conoprobe outperformed the LRS and tracked pointer: for example, the arithmetic means of the SRE over all data acquisitions with a porcine liver were 1.73 ± 0.77 mm, 3.25 ± 0.78 mm, and 4.44 ± 1.19 mm for the conoprobe, LRS, and tracked pointer, respectively. In a cadaveric kidney specimen, the arithmetic means of the SRE over all trials of the conoprobe and tracked pointer were 1.50 ± 0.50 mm and 3.51 ± 0.82 mm, respectively. Our results suggest that tissue displacements due to contact force and attempts to maintain contact with tissue, compromise registrations that are dependent on data acquired from a tracked surgical instrument and we provide an alternative method (tracked conoscopic holography) of digitizing surfaces for clinical usage. The tracked conoscopic holography device outperforms LRS acquisitions with respect to registration accuracy.

A flexure-based steerable needle: high curvature with reduced tissue damage.

In the quest to design higher curvature bevel-steered needles, kinked bevel-tips have been one of the most successful approaches yet proposed. However, the price to be paid for enhancing steerability in this way has been increased tissue damage, since the prebent tip cuts a local helical path into tissue when axially rotated. This is problematic when closed-loop control is desired, because the controller will typically require the needle to rotate rapidly, and it is particularly problematic when duty cycling (i.e., continual needle spinning) is used to adjust curvature. In this paper, we propose a new flexure-based needle tip design that provides the enhanced steerability of kinked bevel-tip needles, while simultaneously minimizing tissue damage.

An Autoclavable Steerable Cannula Manual Deployment Device: Design and Accuracy Analysis.

Accessing a specific, predefined location identified in medical images is a common interventional task for biopsies and drug or therapy delivery. While conventional surgical needles provide little steerability, concentric tube continuum devices enable steering through curved trajectories. These devices are usually developed as robotic systems. However, manual actuation of concentric tube devices is particularly useful for initial transfer into the clinic since the Food and Drug Administration (FDA) and Institutional Review Board (IRB) approval process of manually operated devices is simple compared to their motorized counterparts. In this paper, we present a manual actuation device for the deployment of steerable cannulas. The design focuses on compactness, modularity, usability, and sterilizability. Further, the kinematic mapping from joint space to Cartesian space is detailed for an example concentric tube device. Assessment of the device's accuracy was performed in free space, as well as in an image-guided surgery setting, using tracked 2D ultrasound.

Planning and simulation of microsurgical laser bone ablation.

PURPOSE: Laser ablation of hard tissue is not completely understood until now and not modeled for computer-assisted microsurgery. A precise planning and simulation is an essential step toward the usage of microsurgical laser bone ablation in the operating room. METHODS: Planning the volume for laser bone ablation is based on geometrical definitions. Shape and volume of the removed bone by single laser pulses were measured with a confocal microscope for modeling the microsurgical ablation. To remove the planned volume and to achieve smooth surfaces, a simulation of the laser pulse distribution is developed. RESULTS: The confocal measurements show a clear dependency from laser energy and resulting depth. Two-dimensional Gaussian functions are fitting in these craters. Exemplarily three ablation layers were planned, simulated, executed and verified. CONCLUSIONS: To model laser bone ablation in microsurgery the volume and shape of each laser pulse should be known and considered in the process of ablation planning and simulation.

Including parameterization of the discrete ablation process into a planning and simulation environment for robot-assisted laser osteotomy.

Material processing using laser became a widely used method especially in the scope of industrial automation. The systems are mostly based on a precise model of the laser process and the according parameterization. Beside the industrial use the laser as an instrument to treat human tissue has become an integral part in medicine as well. Human tissue as an inhomogeneous material to process, poses the question of how to determine a model, which reflects the interaction processes with a specific laser.Recently it could be shown that the pulsed CO2 laser is suitable to ablate bony and cartilage tissue. Until now this thermo-mechanical bone ablation is not characterized as a discrete process. In order to plan and simulate the ablation process in the correct level of detail, the parameterization is indispensable. We developed a planning and simulation environment, determined parameters by confocal measurements of bony specimen and use these results to transfer planned cutting trajectories into a pulse sequence and corresponding robot locations.