Morphometric X-ray absorptiometry of the spine: Correlation in vivo with morphometric radiography

The diagnosis of vertebral fractures has been based on lateral thoracic and lumbar spine films and entails the determination of crush, endplate and wedge deformities of the vertebral bodies, generally between T4 and L4. Accuracy and precision of X-ray based morphometry are limited by geometric distortion and other technique-related factors. This paper proposes the use of morphometric X-ray absorptiometry (MXA) as a method which overcomes many of the limitations of morphometric radiography. MXA generates paired anteroposterior and lateral images of the spine using a scanning fan beam geometry that significantly reduces distortions inherent in the cone beam geometry used in conventional X-rays. Intra-observer precision of MXA on 41 subjects aged 65 years and older was 1 mm for vertebral height assessments and 4.7% for vertebral wedge parameters. Linear correlation with vertebral heights and wedge parameters on 32 subjects evaluated by both MXA and morphometric radiography demonstrated a root of the mean squared error of 2.1–2.4 mm and 7.0%, respectively. Vertebral deformities could be identified by MXA. The study documents the feasibility of MXA for the assessment of vertebral deformities. However, further investigation is needed to document the ability of MXA to diagnose prevalent and incident fractures.