DUAL ENERGY X-RAY ABSORPTIOMETRY/DENSITOMETRY (DEXA)
PATIENT INFORMATIONDEXA stands for Dual Energy X-Ray Absorptiometry (or Densitometry). DEXA is a procedure that measures the amount of bone, muscle and/or body fat.
The DEXA determination of bone density or body composition (muscle and fat composition) is performed with an instrument that uses low energy x-rays. For bone density measurements, scans are typically performed of the lumbar (lower) spine, the hip, and the wrist. For body composition measurements, a scan of the entire body is performed. The DEXA instrument is very open consisting of a table and scanning arm (in the shape of a 'C') that houses the x-ray tube on one end of the arm and the detector on the other end.
There is no specific preparation for these studies. However, in terms of eligibility:
DEXA studies cannot be performed if the patient has had a nuclear medicine study within 1 week, or an x-ray procedure using contrast within 72 hours. Please note that DEXA studies should be scheduled before other x-ray or nuclear medicine procedures. If these other procedures are performed before the DEXA procedure and the time elapsed does not meet our protocol, the DEXA procedures will not be performed and the study will need to be rescheduled.
Women who are of child-bearing age must have pregnancy ruled out before undergoing the test. Often this means having a pregnancy test performed within 1 week of the DEXA procedure.
The patient should wear light clothing to the clinic as they will be asked to change into a surgical scrub uniform for the study.
The length of time in the clinic will depend on the number of procedures that are performed. Usually the appointment is for either 1/2 hour or 1 hour.
After changing into a scrub uniform, the patient will have their weight and height measured. For these measurements and scans, patients will remove their shoes. The individual scanning procedures are performed with the patient either lying on top of or sitting next to the scanning table.
For each scan the technologist must perform two steps. First they must perform the scan (scan acquisition); second, they must analyze the scan (scan analysis) to determine the information contained within the scan. The DEXA scans are therefore more complicated than standard x-rays. The DEXA scan is performed to actually measure the amount of bone, muscle or fat.
After the technologist has completed and satisfactorily analyzed the scans, the patient can then change back into their street clothes and leave the clinic.
All scans are reviewed by one of the Nuclear Medicine physicians. A report of the DEXA scan results will be entered into the hospital's computer and record system - usually the same day as the scan.
