DXA Bone Densitometry Interpretation: The Practical Tips


Associate Professor of Radiology Birjand University of Medical Sciences, Birjand, Iran



DXA bone densitometry is the most sensitive and accurate method for bone mass evaluation and osteoporosis diagnosis. However standard scan acquisition and image analysis is crucial for correct diagnosis.
Central DXA for Diagnosis: The WHO international reference standard for osteoporosis diagnosis is a T-score of -2.5 or less at the femoral neck. The reference standard from which the T-score is calculated is the female, white, age 20-29 years, NHANES III database. Osteoporosis may be diagnosed in postmenopausal women and in men age 50 and older if the T-score of the lumbar spine, total hip, or femoral neck is -2.5 or less. In certain circumstances the 33% radius (also called 1/3 radius) may be utilized. Skeletal sites to measure: Measure BMD at both the PA spine and hip in all patients. Forearm BMD should be measured under the following circumstances: 1- Hip and/or spine cannot be measured or interpreted. 2-Hyperparathyroidism 3- Very obese patients (over the weight limit for DXA table). DXA Report: Items That Should Not Be Included:

A statement that there is bone loss without knowledge of previous bone density
Mention of “mild”, “moderate”, or “marked” osteopenia or osteoporosis
Separate diagnoses for different ROI (e.g., osteopenia at the hip and osteoporosis at the spine)
Expressions such as “She has the bones of an 80-year-old,” if the patient is not 80 years old
Results from skeletal sites that are not technically valid
The change in BMD if it is not a significant change based on the precision error and LSC