"We feel it's almost an extension of the physical examination," he said. "It's also extremely cost-effective for us."

He also had a dramatic example of its usefulness. In the run-up to the 2010 Winter Games in Vancouver, a short-track speed skater slipped on the track and stabbed his thigh with his own skate, the sharp, 18-inch blade cleaving through flesh and hitting his femur, leaving a bone bruise. While it seemed a lifetime of training went up in smoke, during a telesongraphy consultation with an expert in Barcelona, Spain, ultrasound scans revealed the blade missed the athlete's tendon. After a surprisingly quick recovery, which was monitored with regular ultrasounds, he went on to win two bronze medals at the Games.


Is it safe?

A big driver for ultrasound is not just that it's relatively less expensive. It's that it might be safer than X-ray-based imaging. The modality uses acoustic energy, not ionizing radiation. But the technology is not inherently risk-free. The two main biological effects of ultrasound are heat and cavitation, or the creation of bubbles which can collapse and injure nearby tissue with shockwaves. Cavitation is what causes pitting in steel propeller blades in ships, according to Frederick Kremkau, an electrical engineer and professor at Wake Forest University School of Medicine.

Speaking to the forum, Kremkau said that in fact, therapeutic ultrasound — now often used in physical therapy to heat up sore limbs — was used before diagnostic ultrasound. And more powerful ultrasound-based systems, called High-Intesity Focused Ultrasound, use precise blasts of acoustic energy to destroy tumors and uterine fibroids.

Still, diagnostic ultrasound uses much lower levels of energy, and the risks are minimal.

"There's no known risk to the use of ultrasound in how we apply it today," Kremkau said.

Dr. Brian S. Garra, a radiologist with the Washington, D.C. VA hospital who also works with the Food and Drug Administration, said diagnostic ultrasound produces 1 watt per square centimeter, less than 1,000th of the power of a HIFU system. Similarly, a lithotripsy device, which uses mechanical energy to break up kidney stones, produces vastly more compressional wave pressure than ultrasound, he said.

Difficulties

But the wider adoption of ultrasound for musculoskeletal or other conditions has to struggle with reimbursement challenges and the nature of ultrasound, which is seen in medicine as more operator-dependent than other modalities. In a morning panel discussion at the conference, one audience member also quipped that ultrasound interpretation was hard even for radiologists.

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