X-ray Bone Densitomer
Have you heard about the Pediatrics department’s new DXA machine?It is true, the department recently bought one to use primarily for research. Dr. Stevenson and others helped to purchase the machine, which was paid for by some research grant funds and by special funding by the CMC Committee. It is located in a newly refurbished room in the radiology department at the KCRC (actually, in the old viewing room). It is run by Drs. Stevenson and Houlihan. So, what is DXA? DXA (pronounced “dexa”) or Dual energy x-ray absorptiometry is a technique for measuring bone mineral density. It utilizes very low-level radiation to give a very reliable (reproducible) measure of bone density, and it is FDA-approved for use in both adults and children. Bone density is typically measured in two sites: the lumbar spine and the hip. In children, the hip has not been found to be as reliable as in adults (because of growth plates) and so total body bone density is also used. In addition, the distal femur has recently been developed as another site for children and is particularly useful for children with disabilities, such as cerebral palsy. As an added bonus, when one scans the total body, the machine can also read percent body fat and lean mass. The focal scans typically take about 20 seconds to attain once the child is positioned. A total body scan takes about 6 minutes, and so it requires a bit of cooperation, but it is definitely doable. Why is all this important? It turns out that osteoporosis is a common problem in pediatrics, but our understanding of it is still pretty limited. Almost any child with a chronic medical condition or physical disability, and any child treated with steroids, is at risk for osteoporosis. This includes cerebral palsy, osteogenesis imperfecta, juvenile rheumatoid arthritis, chronic renal failure, inflammatory bowel disease, cancer, transplant, sickle cell disease, chronic lung disease, cystic fibrosis. Osteoporosis is even a problem in obesity. All this is important because low bone density leads to fractures. Pathological fractures or “fragility fractures” occur fairly commonly in kids with cerebral palsy, spina bifida, spinal cord injury, renal disease and others. This is a particularly important problem in pediatrics because of the whole issue of attaining peak bone mass in late adolescence and early adulthood. Osteoporosis early may contribute to problems for a lifetime. So, it is an area ripe for research. And now we have the tools to study it. In addition to the machine, we have the technical support to do the studies inexpensively (negotiable on whether the research is funded), which is a good news for resident research! So, if you have an interest in any chronic medical illness or disability, and think you might be interested in bones, call Dr. Stevenson! He will be glad to talk to you about the possibilities!