Dual-Energy X-ray Absorptiometry (DEXA) is a quick, non-invasive medical imaging procedure. This test uses two distinct X-ray beams to accurately measure bone mineral density, diagnosing osteoporosis and assessing fracture risk. The scan also provides a detailed analysis of body composition, including muscle mass and body fat distribution. Proper preparation is necessary to minimize interference and artifacts, ensuring the resulting data is accurate for health management.
Recommended Attire
Selecting the right clothing ensures a smooth and accurate scan without delays. Patients should choose loose-fitting, comfortable garments that do not restrict movement, as they must lie still on the scanning table. Soft natural fibers, such as cotton or jersey knit, are the best choices for clothing during the procedure.
Appropriate clothing includes simple t-shirts, sweatpants, or leggings that do not contain metal zippers or excessive stitching. The attire should facilitate easy positioning by the technician, which is necessary for accurately scanning areas like the hip and spine. Arriving in metal-free clothing saves time and simplifies the process, even if the facility offers a disposable gown.
Items That Cause Interference
The DEXA scan relies on X-rays passing cleanly through the body’s tissues. Any dense material in the beam’s path can distort measurements by creating “artifacts”—unwanted anomalies appearing as bright spots or streaks. These artifacts obscure underlying tissue, leading to inaccurately high or low readings for bone density and body composition.
All external metal objects must be removed before the scan, including jewelry such as necklaces, earrings, and rings. Clothing items containing metal components, like zippers, buttons, metal snaps, or metallic threads, must be avoided entirely. Women should also ensure they are not wearing an underwire bra, as the wire can interfere with the chest area of the scan.
Belts, belt buckles, and body piercings should also be removed prior to the appointment. Patients with implanted medical devices, such as pacemakers, spinal fusion hardware, or hip and knee replacements, must inform the technician beforehand. Their density can create artifacts in the scan area, and the technician may need to exclude that specific region from the final analysis.
Essential Preparation Steps
Beyond clothing, several logistical steps ensure the validity of the DEXA scan results. Patients who have recently undergone other imaging procedures involving contrast materials must wait a specific period before their DEXA appointment. Contrast agents, such as barium or intravenous iodine dye, can linger in the body and severely skew the DEXA data by mimicking dense tissue.
A waiting period of at least seven to fourteen days is recommended after a contrast-enhanced exam to allow the material to pass completely out of the system. Patients should also avoid all calcium supplements the morning of the test, and ideally for 24 hours prior. Calcium pills or antacids can temporarily settle in the gastrointestinal tract, leading to a falsely elevated bone density reading in the spine.
It is necessary to inform the facility if there is any possibility of pregnancy, as the procedure involves a low dose of X-ray radiation. If a patient arrives unprepared, the facility may require them to change into a gown or reschedule the appointment to maintain the integrity of the results.