Dexa Scans

UNDERSTANDING DEXA BONE SCAN RESULTS

DEXA scanning is regarded as the "Gold Star" method of diagnosis of osteoporosis and currently is the only method recognised by the World Health Organisation.

The lumbar spine and the hip joint were scanned as these are the main weight-bearing areas of the body and are the most accurate accessible areas to assess.

Measurements of the lumbar spine over at least two, and preferably four vertebrae, are taken and any abnormalities, such as fractures or curvature are noted. These conditions may affect the accuracy of the result but, by including measurements of the hip, the combined results give a good indication as to the state of the bones.

The print-outs give the Bone Mineral Content (BMC) and the Bone Mineral Density (BMD) for each area scanned. The lower part of the print-out plots on a graph the BMD values of the area. There are two scoring systems, the 'T' score and the 'Z' score.

The 'T' score relates to the number of standard deviations the BMD id from the average of a young adult referee aged over 30 and is the WHO criteria for significance of bone density and diagnosis of osteoporosis.

If T score = 0 or >0	BMD is equal to average for population or better.
If T score = 0 to -1	BMD is in top 84% of population - no evidence of osteoporosis
If T score = -1 to -2.5	BMD is a bit low. This is known as osteopenia. Osteoporosis may develop in the future. Preventative treatment to be considered.
If T score 2.5 or worse	BMD is in bottom 2.5% of population - indicating osteoporosis and treatment is advisable.

The Consultant Radiologist will diagnose on the basis of the total hip score and the Ll-L4

Average score, after taking into account any other relevant factors.

The 'Z' score is helpful to a specialist in interpreting certain atypical or borderline cases.

This information sheet is, obviously, not intended to be exhaustive in the diagnosis of osteoporosis but only as a guide to understanding the results.