Manhattan Beach, CA--One out of every two women and one out of every five men in the U.S. today will suffer from osteoporosis, a disease characterized by low bone mass and increased risk of hip, spine, wrist, and other fractures, according to the National Osteoporosis Foundation. A progressive disease, osteoporosis usually strikes older people and results in over 1.5 million fractures per year in the U.S., costing healthcare systems more than $14 billion per year.
Treatments exist, and the disease is preventable if detected early. In fact, there are more than 25 new osteoporosis drugs in the pipeline. But the disease is under-diagnosed.
A new device from CompuMed--the Digital OsteoView 2000(TM)--may change that. The automated device captures images of the hand using amorphous silicon filmless x-ray detection. Proprietary software analyzes the images to determine bone mineral density and thus detect osteoporosis.
The firm had already developed bone density software that determined bone mineral density from standard hand x-rays and ran a lab that analyzed such x-rays for doctors.
"The bone density measurements that we make from the middle phalanges of the index, middle, and ring fingers are more precise and more accurate that any other bone mass measurements," says David Edelstein, executive director of CompuMed's OsteoSystems Division. He cites three clinical studies, one of which showed the software had a 0.6% precision error and 0.983 correlation to ash weight--found by measuring cadaver bone after analyzing the bone x-rays.
"We use those bones because they're about half cortical (dense) and half trabecular (spongy). These represent the two types of bones in the body," says Edelstein. The software analyzes the bones in 1-mm transverse slices and can determine the soft tissue on either side of a slice. Using the assumption that the phalange is almost a cylinder, the software can project the mass of soft tissue around the top and bottom of the bone as well the sides and subtract it from the x-ray image, leaving only bone.
Analyzing x-rays in the lab is a 15-minute, 20-step process. CompuMed decided to automate the process to reduce lab costs--and to build a machine that could take the hand images and automatically run the bone density software.
The OsteoView uses an aluminum alloy reference wedge placed next to the index finger and runs an enhanced version of the bone density software. "We look at the optical density of the wedge image on the film or the digital image, and we compare it to the known material density of that wedge," explains Edelstein. "From that we can calculate the contribution of various conditions such as x-ray spectrum drift, then correct the measured bone mass."
Traditional x-ray machines are not tightly calibrated, he says, and doing so can be expensive. The OsteoView corrects for calibration drift in software using the reference wedge.
The other key component of the machine is the amorphous silicon flat-panel detection technology CompuMed licensed from Varian Associates. The technology was developed by Varian and Xerox Corp. under a grant from the U.S. Defense Advanced Research Projects Agency (DARPA).
"We've done bone density measurement with CCDs, but amorphous silicon will let us get extremely high resolution in a very light-efficient way," says Edelstein. The detector is so sensitive that it reduces the x-ray dose from 30 to less than 1 millirem.
The amorphous silicon detector works like an active-matrix LCD, but in reverse. When x-rays pass through the hand, they strike the phosphor layer, which emits light. The light is picked up by the photodiode layer, which sends out a charge through the thin-film transistor layer. The charge goes to ASICs on a readout board, and is reconstructed into a digital image. Each pixel is 127 microns square, and Edelstein says the resulting image is just about as good as x-ray film.
The high resolution of the amorphous silicon detector combined with the improved software can do fine detail analysis of bones and joints that has not been possible with the current generation of x-ray and ultrasound densitometers. Such fine detail analysis is the key to detecting arthritis as well as reliably and quickly tracking changes that result from osteoporosis and arthritis treatments, says Edelstein.
CompuMed plans to release the Digital OsteoView 2000 after concluding clinical trials and U.S. FDA 510(k) marketing clearance later this year.
Additional details...Contact David Edelstein, Executive Director, OsteoSystems Division, CompuMed, 1230 Rosecrans Ave., Manhattan Beach, CA 90266, Tel: (800) 421-3395, FAX (310) 536-6128, website www.compumed.net.
Other Applications
- Rheumatoid arthritis detection
- Osteoarthritis detection
- Monitoring effectiveness of osteoporosis/arthritis treatment
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