Real-Time Reassurance
By Claudia Stahl  
Radiology Today     
Vol. 24 No. 4 P. 14

Intraoperative MRI proves its value in pediatric neurosurgery.

Reassurance is a precious gift to families of children who have complex neurological conditions, especially following advanced procedures like brain surgery. With the opening of a new intraoperative MRI (iMRI) neurosurgery suite this past March, reassurance is something that the neurosurgery team at Children’s Minnesota hopes to provide more of to the patients in their care. The Minneapolis based, not-for-profit pediatric hospital received a $4 million donation from the Richard M. Schulze Family Foundation to equip the suite with a moving scanner and moving patient MRI. 

The suite’s hybrid configuration allows the clinical team to move a 3T MRI scanner, mounted on a ceiling track, directly from the facility’s diagnostic room into one of the space’s two neurosurgery operating rooms (ORs). The floorplan also allows patients in the suite’s second OR to be moved next door into the diagnostic room for a mid procedure MRI.

While iMRI is not new to the Children’s Minnesota system— the St. Paul campus has offered it for 20 years—Meysam Kebriaei, MD, the director of neurosurgery, says the design is the first of its kind in North America, and “a game changer for us. We care for more kids in our neurosurgery department than any other hospital system in the state.” The new technology and system “will help our patients have the best possible outcomes,” says Kebriaei, whose treatment areas include brain and spinal cord tumors, as well as epilepsy.

iMRI in Pediatric Neurosurgery
Postprocedurally, neurosurgeons rely on MRI to confirm the success of an operation, for example, whether a tumor was fully resected or cancerous tissue remains that should be removed. iMRI gives surgeons these answers while the patient is still on the operating table rather than hours or days after the patient has left the OR.

Oregon Health and Science University Doernbecher Children’s Hospital in Portland has completed 301 pediatric surgical cases using iMRI since its suite was installed in 2016. Christina Sayama, MD, MPH, a neurosurgeon at Doernbecher, says iMRI can add as many as two hours to the length of a procedure because it involves consultation with radiologists and, sometimes, other neurosurgeons during the procedure. The surgeon and radiologists evaluate scans and, when needed, perform additional surgery. If imaging taken after the resection shows that a piece of tumor remains, for example, it’s removed on the spot, eliminating the need for a follow-up surgery.

“It adds a lot [of time] from a provider perspective,” Sayama says. “But after we’re done, I can go out and talk to families and say, ‘The radiologist and I didn’t see any residual tumor’ or ‘I left some tumor on the brain stem because it’s not safe to get it, but I like the shape as much as possible and there’s no evidence of any stroke.’ It gives families peace of mind in real-time when surgery stops.”

A Safe and Established Model
The Brigham and Women’s Hospital in Boston pioneered iMRI in 1994. By 2014, more than 100 centers were using iMRI, according to an article published that year in Translational Pediatrics. Despite the high costs of iMRI, the model has spread from academic to community clinical centers.

While the literature is limited, it “indicates that this technology is safe and can bring multiple benefits to several types of neurosurgical procedures,” wrote Ian Mutchnick, MD, and Thomas M. Moriarty, MD, in “Intraoperative MRI in Pediatric Neurosurgery—An Update.” According to the authors, both pediatric neurosurgeons with the Norton Children’s health system in Louisville, Kentucky, iMRI in the pediatric setting is helpful for managing small, discrete tumors with poor differentiation from surrounding brain tissue, large tumors with surrounding edema, and some cases of catheter/cerebrospinal fluid diversion.

“The attributes of an [iMRI] system are clear: real-time imaging without an increase in infectious or complicative risks,” the authors wrote. “As such, it is no surprise that despite the costs of [iMRI] in an increasingly cost-conscious health care system, the spread of this technology will continue.”

A 2017 article in the Journal of Neurosurgery: Pediatrics notes that iMRI in children is “most effective in increasing the extent of tumor resection, especially in patients with low-grade gliomas and craniopharyngiomas.”

Having used iMRI successfully with adult patients during her residency, Sayama championed Doernbecher’s decision to implement pediatric iMRI seven years ago. “I’m not aware of greater risks in using iMRI in the pediatric [vs adult] population,” she says. “Using iMRI just makes sense. Almost every single time I’ll go back and look at something … even to confirm that taking it out is not going to hurt the patient. I’d rather get it all than leave something behind that may be a tumor.”

According to the literature, the rate of having to go back to remove the remaining brain tumor following the initial procedure is approximately 30%, Kebriaei says. “So it’s not an insignificant number of patients where, under the microscope, it looks like you’ve removed all of the tumor” and MRI reveals otherwise.

Taking that “second look” at the point of surgery can obviate the need for additional operations and, potentially, radiation treatment (in the case of residual tumors), both of which have associated risk factors and consequences. Since most pediatric patients require sedation to undergo MRI, imaging during surgery while the patient is anesthetized eliminates further exposure to those risks.

William Mize, MD, the medical director of radiology at Children’s Minnesota, says scans taken at the time of operation are “cleaner” and more diagnostically accurate than those taken days later, owing to the accumulation of fluid and other factors related to the body’s inflammatory response following a procedure. Postoperative changes can be similar in appearance to a tumor, “so it’s safer and lower impact for the patient if you can solve the problem at the time of the original operation,” he explains.

iMRI can also reveal movement of the brain during surgery, a common occurrence that can result in critical digressions from a presurgical scan. At a level-4 pediatric epilepsy center such as Children’s Minnesota, “even that few millimeters of tissue that we can’t see on the microscope, but we can see with an MRI, makes a difference between our patient having complete freedom from seizures vs ongoing seizures after a big surgery,” Kebriaei says.

Preparation and Staffing
Finding funding to support the equipment and space is likely the biggest obstacle for any hospital looking to add an iMRI suite to its portfolio of services. When redundancy is a concern, it helps to demonstrate how the iMRI suite improves efficiency and benefits multiple specialties.

At Children’s Minnesota, the suite’s design makes it possible to transport children who require anesthesia for diagnostic scanning from the OR “next door” for imaging, “as opposed to having the patient induced and then brought to a different floor to the radiology department,” Mize says, citing one example.

And since the imaging suite has separate access, radiologists and other specialists can perform diagnostic imaging with a 3T MRI while the ORs are in use for surgery without any disruption. As with many facilities where it can be challenging to get on the MRI schedule, “this will add capacity to our system,” he notes. 

Working in an iMRI suite requires strict adherence to MRI safety protocols, and that calls for specialized knowledge and certification for any staff who plan to work in that space. According to Sayama, a safety officer at Oregon Health and Science University ensures that these requirements are followed in the iMRI, and everyone on site during an operation—from the anesthesiologist to the nursing staff to residents and fellows— must be trained in MRI safety.

“We’re pretty restrictive. We don’t allow people into our iMRI rooms, even OR staff, unless they’ve had appropriate training and testing,” she says. “It’s nice for me because I’m becoming more familiar with the people whom I work with on a regular basis (due to their MRI training).”

Sayama says it takes longer to set up the iMRI suite for surgical procedures due to the specialized equipment and the need to meticulously count any instruments that will be used during the surgery. In the early days of Doernbecher’s iMRI suite, finding enough MRI-trained staff for the room “made it challenging to get cases done, but it’s not as much of an issue now that we have enough people” with the necessary skills, she says.

Innovation and Collaboration
At Children’s Minnesota, multiple staff contributed to the design of the iMRI suite, which Mize says “created a really fertile environment for different disciplines to come together and contribute novel ideas.” For example, one of the hospital’s anesthesiologists suggested having a scanner that comes into one OR—which, by design, is limited to head and cervical spine scans—as well as a moving, MRI compliant table in the second OR that can travel to the MRI in the adjacent diagnostic room for a full-body scan.

Kebriaei says many iMRI scanners allow imaging of the brain but not the spinal cord, but the one at Children’s Minnesota has this capability. “It’s really helpful because, in a lot of cases, spinal cord tumors look and feel very similar to normal spinal cord tissue, and so the best way to know that you’ve removed enough is with an MRI scan.”

With a much smaller volume of neurosurgical patients than their adult counterparts, pediatric medical centers are unlikely to offset the costs of an iMRI with cases alone. The payoff, instead, is measured in better outcomes for patients and opportunities for multiple work centers to use the space and technology.

Travis Kruse, MD, division chief of pediatric radiology at Children’s Hospital & Medical Center in Omaha, Nebraska, says a number of specialty teams, from cardiology to oncology, have expressed interest in the iMRI since it opened in 2021. Currently, the hospital is developing a new workflow with orthopedic surgery to manage patients admitted at night. Rather than pulling in a team to manage the patient immediately, “we’ll have the iMRI blocked off at 6 or 7 the following morning for those patients,” Kruse says. “That way, if they find an infection during the scan that requires surgical intervention, we can transfer the patient to the OR right there while on the same anesthesia.” The new model improves staff satisfaction and patient safety, he explains.

Kruse expects cardiology procedures such as ablations to eventually find their way to the iMRI suite and that more specialties will find innovative uses for the space when they realize its potential as an added resource. “Hospitals aren’t going to give up time on the workforce scanners for research or to try novel techniques, they’re just too valuable,” he says. “But when you have an MR/OR, you have the opportunity to try different things. That’s where I see it being advantageous.”

Mize envisions a similar process unfolding at Children’s Minnesota. The iMRI suite “will be an opportunity for innovation because of its widely varying capabilities,” he says. “There are things we’ll be able to use the setup for that we haven’t even thought of yet. So we’re excited about the future.” 

— Claudia Stahl is a freelance writer based in Ambler, Pennsylvania. She specializes in writing about the health of people and the planet.

Notes on Intraoperative MRI

Neurosurgeons rely on intraoperative MRI (iMRI) to do the following:
• locate abnormalities, eg, shifts in the brain during surgery;
• distinguish abnormal brain tissue from normal brain tissue and confirm successful removal of the entire brain tumor; and
• protect critical structures, eg, to keep temperatures low during laser interstitial thermal therapy to treat epilepsy.

Doctors use iMRI to assist in the surgical treatment of the following:
• brain tumors;
• dystonia;
• epilepsy;
• essential tremor;
• glioma;
• neuropsychiatric disorders;
• Parkinson’s disease;
• pediatric brain tumors; and
• pituitary tumors.

Typical configurations for iMRI include the following:
• portable iMRI devices that move into the operating room; and
• nearby iMRI devices that allow doctors to easily move the patient to and from imaging during surgery.

— CS