Advanced Imaging of the Macrostructure and Microstructure of Bone

Abstract

Noninvasive and/or nondestructive techniques are capable of providing more macro- or microstructural information about bone than standard bone densitometry. Although the latter provides important information about osteoporotic fracture risk, numerous studies indicate that bone strength is only partially explained by bone mineral density. Quantitative assessment of macro- and microstructural features may improve our ability to estimate bone strength. The methods available for quantitatively assessing macrostructure include (besides conventional radiographs) quantitative computed tomography (QCT) and volumetric quantitative computed tomography (vQCT). Methods for assessing microstructure of trabecular bone noninvasively and/or nondestructively include high-resolution computed tomography (hrCT), micro-computed tomography (µCT), high-resolution magnetic resonance (hrMR), and micromagnetic resonance (µMR). vQCT, hrCT and hrMR are generally applicable in vivo; µCT and µMR are principally applicable in vitro. Although considerable progress has been made in the noninvasive and/or nondestructive imaging of the macro- and microstructure of bone, considerable challenges and dilemmas remain. From a technical perspective, the balance between spatial resolution versus sampling size, or between signal-to-noise versus radiation dose or acquisition time, needs further consideration, as do the trade-offs between the complexity and expense of equipment and the availability and accessibility of the methods. The relative merits of in vitro imaging and its ultrahigh resolution but invasiveness versus those of in vivo imaging and its modest resolution but noninvasiveness also deserve careful attention. From a clinical perspective, the challenges for bone imaging include balancing the relative advantages of simple bone densitometry against the more complex architectural features of bone or, similarly, the deeper research requirements against the broader clinical needs. The considerable potential biological differences between the peripheral appendicular skeleton and the central axial skeleton have to be addressed further. Finally, the relative merits of these sophisticated imaging techniques have to be weighed with respect to their applications as diagnostic procedures requiring high accuracy or reliability on one hand and their monitoring applications requiring high precision or reproducibility on the other.

Compressive axial mechanical properties of rat bone as functions of bone volume fraction, apparent density and micro-ct based mineral density

“…Given the recent advances in speed, resolution, and reduction of artifacts in medical imaging (Genant et al, 2000; MacNeil and Boyd, 2007), and ever increasing computing power of personal computers (Moore, 1965), virtual alternatives to conventional invasive procedures are becoming increasingly feasible (Bagi et al, 1992; Ferretti et al, 1995; Ferretti et al, 1996; Van Rietbergen et al, 1999; Newitt et al, 2002; van Rietbergen et al, 2002; Martin et al, 2004). Virtual Biomechanics, or the assessment of mechanical strength of skeletal tissue through alternate non-destructive means, enables one to perform longitudinal in-vivo assessment of bone strength to reduce the number of subjects and the costs associated with a study and facilitate the evaluation of multiple skeletal sites from the same subject.…”

Site-Specific Deterioration of Trabecular Bone Architecture in Men and Women With Advancing Age

“…Conventional methods of bone densitometry, however, do not allow analysis of trabecular bone struc-ture to be performed, whereas trabecular bone structure may determine bone strength partially independent of BMD. (6,7) Histomorphometric measurements of trabecular bone samples from the iliac crest and lumbar vertebae showed a significant, parallel, and highly correlated age-related decrease in trabecular bone volume (TBV) and a strong (independent) correlation of iliac crest TBV and age with vertebral strength. (8) This age-related deterioration of trabecular bone structure was confirmed at the iliac crest, (9)(10)(11)(12)(13)(14)(15)(16) the vertebral bodies, (16)(17)(18)(19) and other skeletal sites.…”

Bone‐composition imaging using coherent‐scatter computed tomography: Assessing bone health beyond bone mineral density

“…8 Alternatively, highresolution computed tomography ͑CT͒ and magnetic resonance imaging ͑MRI͒ can provide structural information about the trabecular network throughout the bone marrow region in images acquired with an in-plane resolution of 150 m or less. [9][10][11] Despite recent advances in imaging technology, histomorphometry or ashing of biopsy samples remains the standard for assessing the structure and mineralization state of bone. 12 In histomorphometry, a biopsy specimen is preserved in 70% ethanol, then dehydrated, and defatted by processing through a series of ethanol and acetone washes.…”