Minimally Invasive Intervention for Intracerebral Hemorrhage
Intracerebral hemorrhage (ICH), or bleeding in the brain, is a life-threatening condition which occurs with a frequency of 24.6 per 100,000 person-years. This means that approximately 1 in 50 people are likely to have an ICH in their lifetime, given current life expectancy. The high incidence, 40% mortality rate, and high frequency of debilitating complications even in patients who survive, makes ICH a compelling public health challenge. An ICH occurs when a cerebral blood vessel ruptures, causing blood to escape into the brain and pool, forming a hematoma (a collection of semi-clotted blood outside the blood vessels) which compresses surrounding brain tissue.
ICH is typically treated with medication and observation. In some cases, open surgery is attempted to remove the hematoma. This is because it is commonly believed by neurosurgeons that there is an at-risk volume of brain tissue that can be saved, provided it can be decompressed – . This provides strong motivation for surgical intervention, yet traditional surgical approaches have not been effective in reducing overall mortality rates to date, and there remains no treatment of proven clinical benefit for the majority of ICH patients. ICH debulking poses a different challenge, since it requires dexterous motion of the needle tip within the hematoma. Concentric tube robots have been previously explored in bench-top, animal, or cadaver experiments for a variety of neurosurgical applications requiring steering of a needle-sized curved device.
Research Members: Isuru Godage and Robert J Webster
Phantom Model Experiments to evaluate the effects of Open vs Closed Loop Aspiration
The brain phantom was made of 5% by weight KnoxTM gelatin, formed in a brain mold. This concentration has been shown to provide some mechanical properties similar to mouse brain tissue, particularly in terms of shear modulus. The hemorrhage was also composed of Knox gelatin but with a 2% by weight concentration to represent the semi- coagulated blood in a hematoma. The hematoma was molded first, and embedded in the brain gel before it was fully solidified. The hematoma was shaped in a 45 mm diameter spherical mold with Barium Sulfate added for CT contrast enhancement (0.5% by weight).
The open-loop experiment was designed to evaluate whether the hematoma could be safely aspirated without iterative imaging and re-planning. Upon completion of the procedure, a CT scan was taken. Upon close inspection of the CT images, it is evident that the aspiration process damaged healthy brain tissue due to tissue deformation, despite the planned 5 mm safety margin. The closed loop experiment used iterative CT imaging with re- planning with the goal of improving safety and accuracy. The procedure was divided into 3 iterations, with a CT image volume collected at the start of each. The first iteration lasted approximately 1/4 of the duration that would have been required for a full open-loop experiment. A new motion plan was generated for the second iteration to remove 1/2 of the remaining clot volume. The third and final iteration removes the remaining clot. The figure illustrates that the expected hematoma volume has been removed with no appreciable damage to surrounding brain tissue.
Initial Cadaver Porcine Experiments
The objective of the experiment was to follow the clot-inducing procedure on a euthanized porcine model. As the pig skull thickness vary greatly as they age, it is important to obtain the pre-operative images to verify the depth, thickness. Once the necessary details were taken, the surgical procedures were conducted by a qualified surgeon to expose the skull. A few trial holes varying in diameter were drilled using standard bits. Then 2ml of blood taken from the animal was injected into substantia grisea down 10mm from the surface. To assess the brain deformation during the aspiration process, titanium beads (1mm) were placed around the clot.
(Left) exposed skull with drilled holes, (Middle) inducing the ICH, (Right) implanting the Ti beads
Post-operative imaging was done to verify the procedure. The results showed that the procedure has been successful. The figure to the right shows the CT scan of the beads.
In Vivo Porcine Model Experiments
The goal of this experiment was to evaluate the complete surgical flow using the proposed minimally invasive ICH aspiration robot. The experiment was conducted using MRI imaging. This experiment was conducted with the help of Vanderbilt University’s animal facility and graduate researcher Chen Yue at the Mechanical Engineering Department.
One key component of the robot system is the MR conditional aiming device which as 4 DoF to aim for any position within its workspace. It can be rigidly attached to a special hog board that was designed to fit inside the MRI scan space. Based on the preoperative imaging, one can isolate the blood clot in the brain and its location, shape in the MRI coordinate frame. The data is then used to set the parameters of the aiming system to accurately reach any desired point in the clot. The figure to the right shows the aiming device validation using magnetic tracking system (NDI Aurora).
An ICH is then created in the pig brain after which the pig is mounted on the hog board. The aiming device is then rigidly attached as well as the pig snout within the aiming device using Velcro wraps. The initial MR scan is then taken.
(L) Pig mounted on the hog board, (R) Pre-operative MRI image setup
Once the MR image is analysed (segmentation, fiducial markers using the Slicer), the aiming parameters are solved. The aiming device is then adjusted to hit the desired point inside the clot (center of gravity in this case). The needle tip aspiration path is also computed using a path planning algorithm based on a greedy solver. The robot is then inserted in the clot, and the aspiration process commenced.
(L) The pre-op MRI image of the clot (cicled), (R) The ICH robot aspirating the ICH
Upon completion, the blood sucked in to the tube is taken out and measured. A post-operative CT image is also taken to compare the damages sustained to the brain. This is one of the reasons that real-time feedback is required to accommodate the brain shift during the aspiration process. As a very conservative path with large margin was planned for the evacuation, the possibility of damages to the brain is greatly reduced. But at the cost of amount of blood aspirated. The measured volume removed was around 30% of the original 2ml clot.
(L) The blood aspirated by the robot. (R) Post operative CT image of the removed clot
Disposable Intra-cerebral Hemorrhage Evacuation Robot
The goal of this ongoing project is to develop a low-cost, reliable ICH robot for profitable mass production. The robot mechanism was drastically changed to reduce the footprint for high volume production (injection molding) and incorporate off the shelf, low-cost parts. Because of the low-cost parts, the reliability can be of question. In order to address this, we used redundant sensors to operate the robot accurately and reliably.
(Left) The CAD design of the robot showing the carriages with embedded motors, (Right) The assembly of the prototype robot
- Isuru S. Godage, Andria A. Remirez, Kyle D. Weaver, Michael Miga, and Robert J. Webster III, “First ever in-scanner results for robotic ICH removal”, in the 4th Vise Symposium, Vanderbilt University, 2015 [poster].
- Y. Chen, Isuru S. Godage, S. Sengupta, C. Liu, K. D. Weaver, E. J. Barth, R. J. Webster III, “An MRI-compatible Robot Steerable Needle for Intracerebral Hemorrhage Removal”, in Journal of Medical Devices (JMD), 2017, V001T08A019. Won 3rd place in the three in five competition.
- Saramati Narasimhan, Jared A. Weis, Isuru S. Godage, Robert J. Webster III, Kyle D. Weaver, Michael I. Miga, “Development of a Mechanics-Based Model of Brain Deformations during Intracerebral Hemorrhage Evacuation“, in SPIE International Conference on Medical Imaging, 2017, pp. 101350F-101305F.
- Josephine Granna, Isuru S. Godage, Raul Wirz Gonzalez, Kyle D. Weaver, Robert James Webster III, Jessica Burgner-Kahrs, “A 3D Volume Coverage Path Planning Algorithm with Application to Intracerebral Hemorrhage Evacuation“, in IEEE Robotics and Automation Letters (RAL), 1(2), 2016, pp. 876-883.
- Yifan Zhu, Phil J. Swaney, Isuru S. Godage, Ray A. Lathrop, and Robert J. Webster III, “A Disposable Robot for Intracerebral Hemorrhage Removal“, in Journal of Medical Devices(JMD) 10(2) 2016, pp. 020952.
- Isuru S. Godage, Andria Ramirez, Raul Wirz, Kyle Weaver, Jessica Burgner-Kahrs, and Robert J. Webster III, “Robotic Intracerebral Hemorrhage Evacuation: An In-Scanner Approach with Concentric Tube Robots“, in IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), 2015, 1447-1452.