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DXR for hand BMD measurement may help predict hip fracture risk
Investigators noted the technique proved an effective predictor of hip fracture risk in men and women and could potentially be low-cost per examination.
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Swedish researchers contend that digital X-ray radiogrammetry, or DXR, used on standard hand radiographs to measure bone mineral density may also be useful to help clinicians identify individuals at an increased risk of hip fracture. Furthermore, the investigators believe the technique can be used preventatively to identify patients who are on the borderline of being at risk of developing osteoporosis.
“If we can identify people with osteoporosis and treat them with drugs, we can reduce the risk of hip fracture,” Torkel B. Brismar, MD, PhD, lead author and associate professor of radiology at Karolinska Institute’s Department of Clinical Services, in Stockholm, stated in a press release.
“Our research shows that DXR is a technique that lends itself well to this, maybe at general health check-ups, or screenings, for example, or when people seek treatment for a suspected hand or wrist fracture,” Brismar said.
Torkel B. Brismar
Michael L. Wilczek
DXR as a fracture predictor
Although dual-energy X-ray absorptiometry (DXA) is the standard method for measuring bone density, Brismar, Michael L. Wilczek, MD, and colleagues found that DXR was at least as effective as DXA. They noted that this means DXR may eventually be an important feature of osteoporosis examinations and a part of general screenings.
There is a relation between bone mineral density (BMD) and risk of fracture, but not everyone who should have their BMD assessed is able to, Wilczek noted. Reasons for this include the availability and cost of DXA scans, gold standard when it comes to BMD examinations, he said.
This radiograph shows the wrist of an osteoporotic woman aged 71 years whose overall digital X-ray radiogrammetry (DXR) bone mineral density (BMD) was 0.410 g/cm2. Her DXR T-score and DXR Z-score, respectively, were -3.6 and -1.6..
Images: Wilczek ML
“Our study shows that DXR predicts hip fracture risk for both women and men using radiographs obtained at emergency hospitals,” Wilczek told Orthopaedics Today Europe. “This suggests that DXR could be used to identify patients with increased fracture risk already in the emergency department, eg, at the time of a suspected wrist fracture. Further studies are warranted in order to determine clinical thresholds and to see if DXR could be used for osteoporosis screening,” he said.
For this woman with osteopenia, aged 56 years, DXR BMD was 0.512 g/cm2. Her T-score and Z-score were -1.5 and -1.2, respectively.
By comparison, this DXR wrist radiograph was of a 45-year-old woman who had a normal DXR T-score of -0.3.
Older patients
The researchers studied radiographs of 8,000 men and women aged 40 years and older taken at three hospitals in Sweden between 2000 and 2008. When Brismar, Wilczek and colleagues analyzed the images, they found DXR could predict low BMD in a subgroup of 122 patients with hip fractures occurring after the radiograph was taken that were cross-referenced in Sweden’s National Board of Health and Welfare fracture registry.
DXR uses a normal radiograph of the hand to automatically analyze metacarpal bone thickness and texture via about 1,000 measurements, as noted in the press release.
In the study that Brismar and colleagues carried out all fractures occurring after the radiograph could be found by cross-reference in the fracture registry by using the individual social security codes used by all citizens in Sweden.
In the analysis by Brismar, Wilczek and colleagues, the 122 patients who suffered a hip fracture had significantly lower BMD than the patients without a hip fracture at the same time point. Based on the press release, the results also held up after the investigators adjusted for patient age.
As noted in the press release, Wilczek said that with just an internet connection and the ability to obtain digital radiographs, “[DXR] could potentially be offered at many locations at a relatively low cost per examination.” – by Susan M. Rapp
- Reference:
- Wilczek ML. Eur Radiol. 2012. doi:10.1007/s00330-012-2706-9.
- For more information:
- Torkel B. Brismar, MD, PhD, can be reached at the Department of Clinical Sciences, Intervention and Technology, Karolinska Institute, Stockholm, Sweden; email: torkel.brismar@karolinska.se.
- Michael L. Wilczek, MD, can be reached at Karolinska Institute, Department for Clinical Science, Intervention and Technology, Division of Radiology, Karolinska University Hospital, Stockholm, Sweden; email: michael.wilczek@ki.se.
Disclosure: The authors conducted the study with financial support from the Stockholm County Council. Sectra, a software developer for DXR, analyzed material free of charge and employs two study coauthors.