The benefits of intraoperative MR Q&A with Dr. John Huston

Dr. John Huston

April 09, 2019
by Lauren Dubinsky , Senior Reporter
Mayo Clinic first started performing intraoperative MR procedures over 15 years ago, but the technology and the applications it’s used for have drastically changed during that time.

Dr. John Huston, a neuroradiologist at Mayo Clinic in Rochester, Minnesota, spoke with HealthCare Business News about the benefits that intraoperative MR brought to his health system and their patients, as well as the direction this technology is headed in.

HCB News: Can you tell us a little bit about when Mayo first got involved in intraoperative MR and what factors went into that decision?
Dr. John Huston: The first endeavor in combining operative procedures with MR was called the “double donut.” It was the result of a collaboration between Brigham and Women’s Hospital and GE. It fired the imagination of people to use MR as guidance to perform surgery. That particular project didn’t go very far, but it was the start of the idea.

In about 2002, we started planning, because we felt that the concept of using MR-guided neurosurgery would be beneficial. At the time, there were vendors that were excited about this prospect and came forward with a single-room solution. That involved swinging the table or suspending the MR on a ceiling rail.

We assumed that one of those approaches would become our solution. Due to our collaborative nature, we had the surgeons and anesthesiologists in the room with our planning people, and applying their feedback, we actually took a completely different course.

In a single room where you have a powerful magnet, you have to be very careful about metal projectiles that could be attracted into the magnet. If the patient is there, that can be catastrophic. For safety reasons, we went a different direction and decided to separate the OR and MR, and have a sliding door between the two.

When we began, we found that by having the rooms separate we are able to image our hospital patients at the same time that surgery is going on. It was financially beneficial and improved workflow.

We can use the OR and MR separately when they are not used together for a combined case. It was not the driver at the beginning of the endeavor but it has turned out to be extremely helpful. As our hospital volumes increase, we really need that MR capability.

HCB News: For what patients and procedures has intraoperative MR proved most beneficial at Mayo?
JH: I think, without question – glioma resection. Published reports demonstrate that the more complete the glioma resection, the greater the chance of survival. According to our neurosurgeons, the ability to carefully guide the degree of resection during the procedure has made a big difference.

We are also using it for laser or thermal ablation of the medial temporal lobe in patients with seizures. MR-guided focused ultrasound is an additional application. It is approved for essential tremor treatment and we are also using it for tremor-predominant Parkinson’s disease.

We have used the MR/OR suite a lot for deep brain stimulation, but for efficiency reasons we are not using it as often currently.

HCB News: I know that an MR magnet needs to be in a shielded space; does this create unique challenges for surgical operations?
JH: Not at all, because the rooms are adjacent but separate and we have the MR room RF-shielded. We have developed a culture of safety, where we’re working together to make sure that there are no potential projectiles in the MR space.

By dividing it as we have, the surgeons can use all of their equipment. Some of it is MR-compatible, but in general once that door is shut the clinicians can use the OR as if it’s any other OR.

HCB News: How would you describe the process of bringing new providers into the intraoperative suite? Is there a steep learning curve?
JH: Much of what we are doing is an evolution of what has been done. For example, we have been using image guidance for treatment of a lesion for many years, so it’s taking that experience from the ultrasound or CT environment into the MR world.

We would never do that just because we want to do it with MR. However, there are lesions that you only see with MR, so in order to find the lesion it has to be done in the MR environment.

I think that there are some things that are transformational – and that would include focused ultrasound. With this we can give a test dose to see if that reduces the patient’s tremor before we treat. Then we can increase heating to the level of treatment and have the final result. The advantages of that are that there is no radiation and the results are immediate.

We have a very cooperative relationship with our neurosurgeons. As they brought deep brain stimulation into this space, it was very easy to work with them. It’s more an attitude and a willingness to incorporate new techniques and technology. Once people have that willingness, then the practice changes.

HCB News: Would you say intraoperative MR leads to greater collaboration between radiologists and surgeons?
JH: That has been the case in our practice. By nature, our practice is collaborative. For instance, when we do a placement of a laser, that involves a neuroradiologist working side by side with a neurosurgeon. When we treat with the focused ultrasound, it’s the same thing.

It’s completely different when performing glioma resection because there we are just giving advice about the degree of resection and we are not in the OR during surgery. But in general, it has been an opportunity for us to work closer together rather than be divisive.

HCB News: Does Mayo continue to find new applications for intraoperative MR? If so, can you tell us some of the latest ways it's being utilized?
JH: When we built this space, we did so in anticipation of MR-guided focused ultrasound. We built an adjacent room so that we could put in a focused ultrasound unit, which is now up and running.

We are finding it to be extremely helpful. We are now only doing the standard clinical work. It has been shown that you can open the blood-brain barrier with focused ultrasound to treat gliomas. We are not doing that yet, but we are beginning the research in this area.

In addition, we are currently opening a hybrid three-room image-guided therapy suite to expand our body MR-guided work. This includes MR in the center room, which has been up and running for about a year and a half. On either side of the MR is an interventional CT procedure room.

Sometimes it’s easier to place a probe under CT guidance but once you are treating, MR has the advantage of watching the thermal change of the tissue. If you know that you’ve created a certain temperature and a certain volume, then you know your treatment has been successful.

Our body radiologists are using MR guidance for cryoablation, ablation, and focused ultrasound treatment of prostate cancer. It’s also being used for other applications, including lesioning of liver tumors.

HCB News: Have software upgrades played a role in the expanded capabilities of intraoperative MR?
JH: Vendors are developing better-integrated image management and guidance techniques leading to improved and advanced MR-guided procedures. As images from different modalities are able to be merged, such as ultrasound and CT with MR, better lesion localization and treatment monitoring are possible.

HCB News: In what ways do you imagine image-guided procedures being more advanced in five or 10 years?
JH: I think that image-guided procedures will only continue to increase in complexity and volume. There are many opportunities for providing these services and advancing them. There is no question that a holdup is the technology that is required, but with scale and improvements one can envision this having an increasing impact in health care.

For instance, if you have an essential tremor you have the opportunity to undergo deep brain stimulation. We know that it is effective. However, what about the opportunity to spend three hours in an MR magnet and have a potentially similar outcome without the need to perform the open surgery or purchase the deep brain stimulating hardware?

But there are obstacles. For instance, focused ultrasound is an effective way to treat uterine fibroids, however, because of limited reimbursement it is not widely available. If medicine changes from fee-for-service to a more population-based, managed environment, then we could well migrate to those treatments that are less costly such as image-guided and MR-guided procedures.

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