7T MRI for clinical applications

Currently used for research purposes, the Brigham’s Siemens 7 Tesla (7T) MAGNETOM Terra system is on the brink of receiving approval from the state of Massachusetts. Once approved, the Brigham will be among the first sites in the nation to use the powerful 7T MRI for clinical applications.

Beneath the research labs and clinics of the Hale Building for Transformative Medicine sits a magnetic resonance imaging (MRI) scanner 140,000 times more powerful than the earth’s magnetic field. Currently used for research purposes, the Brigham’s Siemens 7 Tesla (7T) MAGNETOM Terra system is on the brink of receiving approval from the state of Massachusetts that will allow Brigham experts to use it for clinical scanning to diagnose and inform the treatment of patients. The device will be the first of its kind to be used for clinical purposes in the state as well as in New England, and holds critical potential for patients with neurological or orthopaedic conditions.

“The 7T MRI is a game changer,” said Steven Seltzer, MD, emeritus chairman of the Department of Radiology. “We’re excited that we’ll be able to open this device for clinical use in patients for advanced brain imaging and knee imaging.”

In the maturation and evolution of advanced MRI technology, one of the driving forces for improvement is making a magnet capable of generating even greater magnetic field strength. One Tesla of MRI field strength is equivalent to 20,000 times the strength of the earth’s magnetic field. Initially, medical MRI devices operated at field strengths of 0.5 T. Over the last three decades, technical and engineering advances have produced “high-field” MRI devices with field strengths up to 3T, which until now have been the clinical state of the art.

The “ultra-high field strength” of the 7T magnets represent a dramatic advancement beyond the 3T, more than doubling the magnetic field strength which in turn facilitates higher resolution, anatomical images and functional images that can demonstrate brain activation, biochemical fluxes and vascularity.

“Clinical approval of the 7T represents a quantum leap in our ability to help make difficult diagnoses in many of our complex neurological and musculoskeletal patients,” said Srinivasan Mukundan, PhD, MD, medical director of Magnetic Resonance Imaging for Brigham Health. “The milestones on the path to clinical approval that we are reaching today result from more than five years of planning and foresight by the radiology team informed by the combined vision of Dr. Seltzer and current department chair Dr. Giles Boland to bring this device to our campus and then integrate it into our MRI program that focuses on both world-class research and access to the most advanced patient care for our patients.”

While several leading institutions across the U.S. – and across the Charles River – have 7T MRIs on site for research purposes, only the Siemens device has received approval from the U.S. Food and Drug Administration for clinical use. The Brigham is one of four sites in the U.S. that has a Siemens device on its campus and once formal state approval is in place, it will be among the first sites to use the device for patient diagnostics and to guide clinical treatment.

Clinical Capabilities for the Brain and Knee

Although current high-field MRI devices give valuable information about a patient’s condition, Brigham physicians plan to use the new ultra-high field 7T instrument for cases where conventional magnets have historically left clinical questions unanswered. Clinicians who see patients with neurological conditions – such as multiple sclerosis, Parkinson’s disease, Alzheimer’s disease, brain tumors, epilepsy, cerebrovascular diseases and traumatic brain injury – and musculoskeletal conditions are eager to deploy the 7T for clinical use.

Howard Weiner, MD, co-director of the Ann Romney Center for Neurological Diseases, treats patients with multiple sclerosis, a disease that can be challenging to assess using traditional imaging approaches. The 7T may help clinicians perform an “MRI virtual biopsy,” visualizing cortical lesions and central veins in white matter lesions that are essential features of MS.

“The 7T magnet will allow us to visualize MS in a way that we have never been able to visualize it before,” said Weiner. “This will create new opportunities to understand and treat progressive forms of MS, for which we have few treatments.”

Ellen Bubrick, MD, a neurologist in the Department of Neurology, agrees that once the 7T is approved for clinical use, it will open doors for many of the patients she sees. Bubrick specializes in treating patients with epilepsy, many of whom are drug resistant.

“Ideally, we’d like to be able to obtain a high resolution scan on any patient with drug-resistant epilepsy whose 3T scan did not show a lesion,” said Bubrick. “Our research shows that a significant percentage of these patients do in fact have lesions that can only be detected, or at least properly characterized, on 7T. Detecting a lesion improves the patient’s chances of a better surgical outcome significantly.”

The 7T will also allow orthopaedic surgeons to get a non-invasive, detailed picture of various structures within the knee that are often the source of pain and disability in patients. These include the trabecular bone (internal tissue of the skeletal bone), microstructure in trauma and osteoarthritis, collagen ultrastructure and make-up in osteoarthritis and collagen grafts, and tendon and soft-tissue imaging.

“High-resolution images from the 7T may allow the orthopaedic surgeon to detect earlier structural pathologies that cannot be seen if done by conventional MRI scans,” said James Kang, MD, chair of the Department of Orthopaedic Surgery. “This would allow for the development of newer, innovative surgical techniques that can help prevent or limit further damage to these tissues. The more structural details we can see, the more we can diagnose and devise improved treatment alternatives.”

An Eye Toward the Future

Clinical use for the 7T at the Brigham has been in the making for many years, dating back to when planning for the construction of the Hale Building for Transformative Medicine was underway. Seltzer and Mukundan described their initial proposal for housing a 7T on Brigham’s campus as a Hail Mary pass – one that, in five years, would be caught in the end zone.

“When we were thinking ahead to 2018, we asked, ‘What kind of imaging support do we need to help strengthen the clinical programs in the new building?’ The high end of our thinking was that maybe by that time, ultra-high field strength MRI might be FDA approved,” said Seltzer. They went about doing everything they could to plan for that possibility, including building a relationship with the instrument vendor, working with the architects to design and construct the Hale Building to accommodate the installation a 25-ton behemoth of a device, and connecting with clinical colleagues and patient advocacy groups to determine the needs that could be addressed by this novel device.

The Hale Building, where neurosurgery, neurology, orthopaedic and musculoskeletal patients are seen, includes an imaging floor that houses a total five of state-of-the-art MRI scanners and a CT scanner to support the activities of the clinics. The HBTM space was designed to allow for removal of MRI equipment for upgrade and repair, from any of the individual scanner rooms while maintaining operations at the other sites. In May 2017, this unique capability was leveraged as the 7T was lowered by crane into the Hale Building through a specially designed access hatch to a loading platform below. It was then moved through a hold and slowly pushed down the service corridor, a process that took several hours, without disrupting care for patients on the other scanners.

Since the device came online, the 7T has been used in basic and translational research, with projects underway to explore more “basic topics” such as development of novel pulse sequences or quantitative analytic tools to more “translational topics” that explore novel ways to use MRI in patient care. The 7T will be used for both advanced patient care and research going forward, reflecting the Brigham’s longstanding dedication to advanced medical research and to discovering new knowledge that can improve the care of patients.

“Fundamental research and clinical translation have always been critical components of the BWH MRI program in general, and continue to be key elements of our 7T program,” said Mukundan. “We truly believe that ‘today’s research is tomorrow’s practice,’ an aphorism that is particularly apt as our 7T MR program becomes a reality.”