MARINA DEL REY, CALIF. — Thinking about learning ultrasound? You are not alone, according to Dr. Kambiz Motamedi of the radiology department at the University of California, Los Angeles.
In Europe, rheumatologists have been using ultrasound (US) in their offices for years. The use of diagnostic US is catching on among U.S. rheumatologists, too. The American College of Rheumatology is offering its first US course this summer.
Studies, mostly done overseas, suggest its diagnostic value (Rheumatology 2009;48:1,092-7).
Uptake has been slower in the United States because MRI is more readily available and US has a steep learning curve, Dr. Motamedi said during a presentation and workshop on US.
But US is “becoming more and more popular,” among U.S. rheumatologists, he said.
A recent, small study suggests that even self-taught rheumatologists can become proficient ultrasonographers (Arthritis Care Res. 2010;62:155-60).
US is useful to look at superficial structures, including muscles, tendons, ligaments, nerves, and blood vessels, said Dr. Mihaela Taylor of the division of rheumatology at UCLA, who collaborated with Dr. Motamedi on the presentation and workshop.
It has higher soft-tissue resolution than does CT, Dr. Motamedi noted, although CT remains the standard for visualizing bone.
US also can visualize superficial joint structures, and pick up bone erosions, Baker's cysts, fluid behind the patella, and even meniscal tears, if they are in the periphery of the meniscus, acacording to Dr. Motamedi.
Joints can also be seen in motion, meaning that US can help guide joint injections.
“Ultrasound can't replace all that MRI [or CT] does, but it helps diagnose a lot of pathology,” Dr. Motamedi said.
Painless, noninvasive, relatively inexpensive, and free of radiation, it's also readily accepted by patients, Dr. Taylor said.
Although magnetic resonance imaging remains the standard for visualizing deep anatomical structures, such as those of the knee, US is a valid alternative, especially for claustrophobic patients and those with pacemakers or other MRI contraindications. The general concept of US is easy to grasp: Sound waves emitted from a probe are bounced off body structures. Their reflections back to the probe indicate the structure's density. Bone reflects as white. Less-dense structures—those that contain more water—reflect as darker shades.
What's closest to the probe (usually skin) appears at the top of the screen. What's farther away appears lower down.
Anything below bone cortex is artifact. Ultrasound does not penetrate bone, Dr. Taylor said.
Higher sound-wave frequencies mean better resolution but less penetration; lower frequencies penetrate more deeply but give less resolution.
It's helpful to keep the probe in motion and tilt it from side to side to help differentiate structures, Dr. Taylor said.
Information about the American Colege of Rheumatology's US course is at www.rheumatology.org/education/clinicalsymposia/mus.asp
Disclosures: Dr. Motamedi and Dr. Taylor each reported having no relevant financial conflicts.