A new type of X-ray scan already being widely used to test for osteoporosis is proving to be very unreliable, doctors in London and Cambridge have discovered.
Dual-energy X-ray absorptiometry (DEXA) uses two X-ray beams to test for levels of fat, lean tissue and bone mineral in the body.
But when doctors from St George's Medical School in London and Dunn Clinical Nutrition Centre in Cambridge carried out scans on the same six patients at different locations, the findings on fat and lean tissue mass were wildly different.
The manufacturers could find nothing wrong with the two machines, a conclusion backed up by the fact that the bone mineral measurement was almost the same each time.
One patient was given three other scans to try and discover the discrepancy, and the readings were again very different each time (The Lancet, September 30, 1995).