Noninvasive imaging of bone microarchitecture

Abstract

The noninvasive quantification of peripheral compartment-specific bone microarchitecture is feasible with high-resolution peripheral quantitative computed tomography (HR-pQCT) and high-resolution magnetic resonance imaging (HR-MRI). In addition to classic morphometric indices, both techniques provide a suitable basis for virtual biomechanical testing using finite element (FE) analyses. Methodical limitations, morphometric parameter definition, and motion artifacts have to be considered to achieve optimal data interpretation from imaging studies. With increasing availability of in vivo high-resolution bone imaging techniques, special emphasis should be put on quality control including multicenter, cross-site validations. Importantly, conclusions from interventional studies investigating the effects of antiosteoporotic drugs on bone microarchitecture should be drawn with care, ideally involving imaging scientists, translational researchers, and clinicians.

Figure 1

Influence of subject motion of scan-quality HR-pQCT scans of the distal radius of a single individual (left: grade 5—not usable for analysis; middle: grade 3—still usable; right: grade 2—almost motionless, good image quality). Arrows point at artifact streaks induced by rotational motion.

Figure 2

Three examples of HR-pQCT scans of the distal tibia. (A) Normal premenopausal control. (B) Postmenopausal women with chronic kidney disease. Morphologic features include cortical thinning, loss of trabeculae, and severe arterial calcifications. (C) Postmenopausal and age-related cortical porosity with relative preservation of the trabecular compartment.

Figure 3

Comparison of HR-pQCT and HR-MRI in an osteopenic, early postmenopausal woman. Upper row: HR-pQCT of the distal radius and tibia. HR-MRI at identical skeletal sites (below) depicts trabecular structures by inverse contrast.