Magnetic resonance osteodensitometry in human heel bones: correlation with quantitative computed tomography using...

Area of Science:

• Radiology and Imaging Science
• Bone Densitometry
• Biomedical Engineering

Background:

• Trabecular bone density is crucial for skeletal health assessment.
• Quantitative Computed Tomography (QCT) is a standard for bone mineral density (BMD) measurement.
• Magnetic Resonance Imaging (MRI) offers potential for non-invasive bone assessment.

Purpose of the Study:

• To assess trabecular bone structure density using 3D MR gradient echo imaging (GEI).
• To investigate the impact of spatial resolution (pixel size) on GEI signal characteristics.
• To determine optimal GEI parameters for correlating with QCT-derived BMD.

Main Methods:

• 3D GEI with multiple echo times was performed on heel bones of 35 patients.
• Isotropic pixel sizes of (0.6 mm)3, (1.2 mm)3, and (2.4 mm)3 were applied.
• Signal intensity ratios (TE2/TE1, TE3/TE1) were calculated and correlated with QCT BMD.

Main Results:

• T2*-related signal decrease was more pronounced at lower spatial resolutions.
• High correlation (r = -0.86) between GEI signal ratios and QCT BMD was found in the dorsal heel with (0.6 mm)3 resolution.
• Lower correlations were observed in the ventral heel regions with partly thickened trabeculae.

Conclusions:

• Spatial resolution significantly influences T2*-related signal characteristics in 3D GEI.
• Small pixel sizes (e.g., [0.6 mm]3) in GEI yield higher correlations with QCT BMD in specific bone regions.
• Standardized protocols with small pixel sizes and site-specific correlation curves are needed for clinical MR osteodensitometry.