DXA scan basics

A DXA scan (Dual-Energy X-ray Absorptiometry) is a low radiation imaging test to evaluate bone mineral density (BMD).

Tips:

• Should be done at the same facility each time. Otherwise, it is hard to evaluate for clinical change in the BMD.

• Least significant change (LSC)

  • The smallest difference in BMD that is considered clinically significant.

  • This is listed on the DXA report, and will be different at different facilities.

  • A good rule of thumb is 5% change in the BMD.

• Always look at the images yourself. Confirm correct positioning/labeling.

  • The femur should be internally rotated so that the lesser trochanter is barely visible.

• The BMD should increase at each lumbar vertebral level. e.g. BMD for L3 should be greater than BMD for L2. BMD for L2 should be greater than that for L1.

• Look for artifacts that can impact the accuracy of your DXA scan:

  • Arterial calcifications

  • DJD

  • Hardware (e.g. spinal fusion or hip replacement)