Developing an MRI-Compatible Surgical Robot

Building a robot which can go into an MR is a big challenge, you cannot use the conventional components as putting a big projectile inside a magnet is never a good idea. Plus with other electronics, you can get image distortion. It is not as simple as  across the surgical robotics industry. On Episode 7 of The Surgibots Podcast I sat down with Gregory Fischer, the CEO & Founder of AiM Medical Robotics, to discuss the MRI compatible robotics that they are developing. We dove into the details of making a surgical robotics system with MRI compatible components and the unique challenges that poses.  

What does the AiM Medical Robotics system do?  

 The idea is to put robots inside of an MRI scanner. That allows you to place an instrument or tool in exactly the right spot. A lot of the ways they do this in an operating room is using a microelectrode recording. They put these electrodes in and they'll essentially listen for buzzing sounds to make sure that they are getting the right amount of electrical activity, then they pull that out and stick another, more permanent probe inside. You can't get the accuracy you need or guarantee that you're going to be in the target based purely on what's available in the operating room. 

By taking this procedure and putting it inside an MRI scanner we can use iterative intraoperative MRI to look at shifts in the brain. For example, if you want to put something in the brain, you drill a hole, which causes the cerebral spinal fluid to drip out. Similarly, if you start poking at the brain you're gonna get tissue swelling, so things move and change during the procedure and those probe readings are no longer accurate. Working on the images you took before the procedure may be great for targeting relative to the skull, but that system cannot give you perfect targeting relative to the soft tissue anatomy inside your brain. The same thing applies to abdominal anatomy and other parts of the body as well. The idea is to take these probes and get the applicator in exactly the right spot relative to the anatomical structures of the brain. That's where our robot can really help. 

Why is it such a challenge to make a robot that is MRI compatible? 

 An electric motor is the heart of most robots. It's about a steel can, a coil of wire and a magnet, which are probably the three worst things you could put inside an MRI scanner. It’s really exciting to think about how we can create new and innovative technologies that let us put robots inside an MRI scanner and not have them affect the imaging. Safety is a given, so we want to make sure we don't put anything that's going to be ferrous and have a projectile effect that could hurt a patient inside the scanner.  

There's other factors like resonance within the wires that can cause heating, which is a challenge as well. That's why you would usually take off jewellery when you're doing the MRI procedure, because you don't want anything heating up on the patient. On top of that, we want to find ways to build a robot that doesn’t distort the images or create electrical noise. If you were to take any standard electronics and throw them in an MRI room, you get static, streaking or other issues.  

My research over the last 15 years has focussed on how to put ceramic actuators inside an MRI scanner, getting really high precision motion in a very compact form factor without affecting electrical activity. My PhD dissertation was on using air powered pneumatic robots inside MRI. I spent many years of my life doing that, but I've since pivoted into the electric space, and there's huge advantages to going in that direction. We've tried dielectric elastomer actuators which are essentially really high voltages that you put across pieces of rubber to make them move. They're really cool technologies that are MRI-compatible. However, for surgical level patients, we feel very strongly that the electric approach is the way to go. 

To learn more about making an MRI-compatible surgical robot, tune into Episode 7 of The Surgibots Podcast here.