As a small group of McLean Hospital researchers and medical personnel watched intently, a rigging contractor's crane gingerly hoisted its 34,000-pound load — one of the world's most powerful Magnetic Resonance Imaging (MRI) scanners — swung it slowly to the left over a chain link fence and gently lowered the costly cargo near a low building.
Crews of O.B. Hill Trucking & Rigging Co. guided the operator of the 120-ton, GMK 5120 Grove hydraulic crane as he positioned the squat research MRI precisely in front of a narrow opening in a wall of a renovated historic building at the teaching hospital's Belmont, Mass., campus.
According to Bob Molloy, veteran rigging superintendent of the Natick firm, five counterweights totaling 38,000 pounds helped stabilize the crane as it reached out 40 feet with the heavy load. Workers used a winch to pull the research unit mounted on rollers to its permanent place about three feet inside the building, clearing the opening with just inches to spare.
It took only two hours for the precision move of the high-powered MRI. While scanners used in medicine typically have a magnetic field strength of 0.3 to 3 teslas, this one, manufactured by Varian Medical Systems of Palo Alto, Calif., is rated at 9.4 teslas. Stated another way, the magnetic strength of McLean's new MRI is approximately 160,000 times more powerful than the earth's magnetic field.
This kind of power produces very high-resolution images, but it doesn't come cheap. Higher field strengths require more costly supermagnets with higher maintenance costs. While McLean did not reveal the price paid for its new MRI, such a huge magnet can reportedly cost $1 million per tesla.
In addition to the issue of high costs, safety is a concern for institutions planning to install powerful MRIs on their campuses because they can exert forces well beyond their confines. This one does not.
"Because it is actively shielded, meaning that a reverse magnetic field is wrapped around the outside of the machine, the magnetic force is felt only by those within 25 feet of the magnet's core," explained Marc Kaufman, Ph.D., who spearheaded the hospital's drive to obtain the new MRI.
"That means that unlike other MRIs, where the magnetic force may be felt outside of the building where it is housed, the force of the 9.4 Tesla, while stronger, is completely contained within," he said.
According to Adriana Bobinchock, assistant director of public affairs, McLean began preparations for the delivery of the MRI this spring by renovating the building that would house the unit. Working closely with Varian, McLean ensured that the building, which at one time housed blacksmiths and a carpentry shop, met the operating specifications for the machine. And in order to get the MRI into the building, crews had to build a "false wall" that could be opened to allow the 9.5-foot-wide MRI to easily slide into place.
"We could not wait until the MRI was on campus to renovate the building, so we decided the best thing to do was to make our renovations and create a wall with cutout that would accommodate the scanner," said Andrew Healy, director of Facilities for McLean.
"Moving the MRI into the building with the crane was a little like threading a needle — it took precision movement. The delivery and placement of the MRI could not have gone smoother," he said.
Commenting on the move, Peter Paskevich, senior vice president for McLean Hospital's Department of Research Administration, said: "It was an impressive sight, but I have to admit, I think I held my breath while it was being lowered. For those of us who worked for the last four years to bring this MRI to our campus, it was a little like waiting for a child to be born. We were 99.9 percent sure everything would be OK, but we didn't want to cheer until we officially received a thumbs up."
McLean Hospital, which is an affiliate of Harvard Medical School and Massachusetts General Hospital, and a member of Partners HealthCare, will use its new MRI as a scientific research tool to gain insight into such psychiatric and neurodegenerative diseases as schizophrenia, depression, bipolar disorder, dementia, substance abuse, and attention deficit hyperactivity disorder.
(Ed.: A special thanks to McLean Hospital's Assistant Public Affairs Director Adriana Bobinchock for information and photos used in preparing this article.)