A portable, noninvasive ultrasound bone imaging device may one day prove to be a better predictor of fracture risk than currently available technologies, according to scientists at the National Space Biomedical Research Institute (NSBRI) of Houston, Texas.¹

Still under development, the Scanning Confocal Acoustic Diagnostic (SCAD) system is a real-time, high-resolution imaging device that can assess both bone strength and density via scanned, confocal ultrasound. Improving on the capabilities of dual-energy x-ray absorptiometry (DEXA), the SCAD system will also determine the rate of bone loss.

"The DEXA is still the gold standard for osteoporosis assessment, but it certainly has its drawbacks, namely that it only detects bone mineral density (BMD) and it is only available at specialty centers," says chief researcher Yi-Xian Qin, PhD , an associate professor in the department of biomedical engineering and orthopedics at Stony Brook University in New York and an associate team leader of NSBRI's technology development team.

"Not only can SCAD assess the density of the bone, but it can also potentially assess the strength of the bone," he tells CIAOMed, adding that this is the critical parameter for fracture.

Another advantage is that it may be possible to conduct SCAD more frequently than DEXA. "Osteoporosis patients have no pain and often they only [undergo DEXA] once a year or less, but this kind of testing, if it can be developed, can be performed by the general physician and conducted more frequently," Qin points out.

SCAD consists of a computer-controlled miniaturized scanner with data acquisition and analysis software. In the future, the system will be designed to include wireless output for easy data transmission. The entire device is lightweight and easy to carry.

Such technology may help deter the anticipated osteoporosis epidemic. In a first-ever report on bone health, US Surgeon General Richard H. Carmona, MD, recently warned that by 2020, half of all Americans older than 50 will be at risk for fractures from osteoporosis.²

Work in Progress

At this stage of development, SCAD can only do regional bone assessments of the heel. "In the next 4 years, we plan to develop it so it can measure the knee and hip as well," Qin says, adding that "eventually this technology can aid diagnosis for a number of skeletal disorders including osteopenia and potentially osteoarthritis."

Going forward, "we want to make it easier to use and a better predictor, and then we will do multiple clinical trials and seek commercial support," he says.

The NSBRI is devoted to health concerns of astronauts. "Loss of bone mass is a huge issue in space," Qin observes. "Astronauts usually lose an average of 2% of bone mass per month due to microgravity."

Better Technology is a Must

Osteoporosis experts, including Felicia Cosman, MD , of Helen Hayes Hospital in West Haverstraw, New York, are acutely aware of the need for enhanced technology to diagnose bone disease.

"The need is for something that will measure quality rather than just density," Dr. Cosman tells CIAOMed. "We need tools to noninvasively assess the microscopic architecture of bone," she says.

For example, "if a technology could better assess and measure the breakdown of bone during estrogen deficiency at menopause, we could refine our ability to predict fracture risk in this population," she adds.

"We know density is just one of the factors that affect fracture risk," Cosman asserts. Other factors can also include holes in the cortical bone. "A new technology could help refine who will fracture and who will not, and may help us monitor therapy better," she says.

Today "we can measure bone turnover, which can be a surrogate measure of quality, but a more direct measure can allow us to better monitor treatment and predict future fracture risk," she says.

"Also on the horizon," Cosman points out, "is microscopic magnetic resonance imaging (MRI) of the spine, also known as virtual bone biopsy." She adds that "this is in the very early stages of investigation."

References

1. Tool to Examine Bone Quality for Space, Earth-Based Diagnosis [press release]. Houston, Texas; National Space Biomedical Research Institute; January 5, 2005.

2. U.S. Department of Health and Human Services. Bone Health and Osteoporosis: A Report of the Surgeon General. Rockville, MD: U.S. Department of Health and Human Services, Office of the Surgeon General, 2004.