Looking at muscles in a new way
Sometimes in medicine, something old becomes new again.
Ultrasound, invented almost 20 years before CT scans or MRIs, and perhaps most commonly associated with pregnancy or electrocardiograms, is now being used to diagnose musculoskeletal disorders such as rotator cuff injuries.
“It is good because it requires only a machine and a well-trained person and does not involve radiation,” says Salvatore Viscomi, MD, a Brigham and Women’s radiologist affiliated with Cape Cod Healthcare.
The radiologists, physician assistants, and sonographers are specifically trained in using ultrasound for musculoskeletal diagnosis and treatment, and are involved in offering this option at the Cape Cod Hospital.
Ultrasound has long been popular for musculoskeletal patients in places such as Europe, Asia and South America partly because it’s a less expensive procedure and uses equipment commonly available. Now, doctors at places such as the University of Michigan and Cleveland Clinic are studying its use on musculoskeletal patients, although few radiologists in this country are certified for that use, Dr. Viscomi said.
The most common scan used on musculoskeletal patients is MRI, magnetic resonance imaging, which uses magnets and radio waves to create cross sections images of the body. CT, or computer tomography, uses X-rays to create cross-sections of a body part.
Ultrasound, which looks straight into the body rather than in slices, works on a simple principle: Sound waves transmitted through the skin bounce off the body. A transducer – similar to a handheld supermarket scanner – is held against the skin and picks up the bouncing waves, turning them into images that can be read by a radiologist or other trained operator.
One of the specialized physicians demonstrated the technology in the Cape Cod Hospital radiology department by moving a transducer along his own healthy wrist. The grey-scale image on the machine moved and pulsed, crossed by threads of tendons and nerves. On the film of a patient’s shoulder, he pointed out tiny black pockets of fluid where the tendon had pulled away from the bone and would have to be repaired.
In many situations, particularly in the diagnosis of tears in superficial tendons or ligaments, ultrasound has several advantages over other forms of scans, Dr. Viscomi said. It does not use radiation. It takes less time than a MRI and is less stressful on patients, particularly those who get claustrophobic in tubular imaging machines or are bothered by the seemingly random banging noise. It’s can be used on patients with pacemakers or neurostimulators who can’t be scanned magnetically.
Ultrasound also allows for movement of the joint, so a doctor can ask a patient to, say, move an ankle to see how an injury has affected its use, he said. In an MRI or CT, the patient must lie still.
Ultrasound can also be a therapeutic tool, he added.
“Say a patient comes with pain in the shoulder and they think it could be bursitis. The scanning physician can look and say, yes, this is bursitis and at the same tine I can guide a needle right into the bursa with steroids or other medication.”
Like any tool, ultrasound is not always appropriate. If there are issues deep in the shoulder with cartilage or the labrum (tissue attached to the shoulder socket that helps keep the ball in place) or bone marrow, for example, an MRI would be required, Dr. Viscomi said. Ultrasounds are also more dependent than other scans on the skill of operator – one reason it’s often difficult to get consistent results from ultrasound studies, he said.
And an MRI provides the best overall evaluation of the joint, he said, because it’s possible to see bone contusions, cartilages and the labrum.
That said, Dr. Viscomi believes ultrasound has an important role in the diagnosis and treatment of musculoskeletal problems.
“With the ultrasound, it’s a very specific type of problem you can help. But those you can, it’s better than an MRI.”