Updated practice guideline for dual-energy X-ray absorptiometry (DXA)

Abstract

The introduction of dual-energy X-ray absorptiometry (DXA) technology in the 1980s revolutionized the diagnosis, management and monitoring of osteoporosis, providing a clinical tool which is now available worldwide. However, DXA measurements are influenced by many technical factors, including the quality control procedures for the instrument, positioning of the patient, and approach to analysis. Reporting of DXA results may be confounded by factors such as selection of reference ranges for T-scores and Z-scores, as well as inadequate knowledge of current standards for interpretation. These points are addressed at length in many international guidelines but are not always easily assimilated by practising clinicians and technicians. Our aim in this report is to identify key elements pertaining to the use of DXA in clinical practice, considering both technical and clinical aspects. Here, we discuss technical aspects of DXA procedures, approaches to interpretation and integration into clinical practice, and the use of non-bone mineral density measurements, such as a vertebral fracture assessment, in clinical risk assessment.

Keywords: Dual-energy X-ray absorptiometry (DXA); Practice guideline; Procedures.

Fig. 1

A positioning device should be used to ensure that the patient’s hips and knees are flexed to 90° when scanning the lumbar spine. B When scanning the hip, the ipsilateral foot should be rotated internally by 15°-20° using a specific positioning device containing a strap for immobilization

Fig. 2

A Example Hologic lumbar spine DXA including follow-up. WHO Classification: Normal. B Bottom example GE lunar lumbar spine DXA. WHO Classification: Normal

Fig. 3

A Example Hologic right hip DXA and follow up. WHO Classification: Normal. The patient’s hip was also scanned twice, also showing the variation of BMD values in the graph. B Example GE lunar left hip DXA. WHO Classification: Normal

Fig. 4

A Example Hologic Forearm 1/3 (33%) radius DXA. WHO classification: Normal. B Example GE Lunar Forearm—Radius- DXA. WHO Classification: Osteoporosis

Fig. 5

Examples Hologic VFA DXA. Mild fracture at the vertebral level Th11, grade 1 (left side and mid (same subject but with 6-point markers). Right-sided fractures with moderate wedge at level Th7 and Th8, and a moderate crush fracture at level Th12

Fig. 6

Abdominal aorta calcification (AAC) acquired with DXA

Fig. 7

TBS example of a 61-year-old woman. Normative reference data in children and various ethnicities are limited

Fig. 8

Densitometer-based femur imaging. a Single-energy scan showing beaking on extended-length femur imaging (arrows). b Dual-energy scan showing focal cortical periosteal and endosteal reactions at the lateral cortex (arrow). c Normal image from densitometer-based full-length femur imaging (FFI) with permission of Elsevier [55]

Fig. 9

A Top and bottom: example WBC Hologic of a 11-year-old boy with Duchenne muscular dystrophy and glucocorticoid therapy. B Example WBC GE LUNAR of an adult

Fig. 9

A Top and bottom: example WBC Hologic of a 11-year-old boy with Duchenne muscular dystrophy and glucocorticoid therapy. B Example WBC GE LUNAR of an adult