Ultrasound Simulation in the Distal Radius Using Clinical High-Resolution Peripheral-CT Images

Abstract

The overall objective of this research is to develop an ultrasonic method for noninvasive assessment of the distal radius. The specific objective of this study was to examine the propagation of ultrasound through the distal radius and determine the relationships between bone mass and architecture and ultrasound parameters. Twenty-six high-resolution peripheral-CT clinical images were obtained from a set of subjects that were part of a larger study on secondary osteoporosis. A single midsection binary slice from each image was selected and used in the two-dimensional (2D) simulation of an ultrasound wave propagating from the anterior to the posterior surfaces of each radius. Mass and architectural parameters associated with each radius, including total (trabecular and cortical) bone mass, trabecular volume fraction, trabecular number and trabecular thickness were computed. Ultrasound parameters, including net time delay (NTD), broadband ultrasound attenuation (BUA) and ultrasound velocity (UV) were also evaluated. Significant correlations were found between NTD and total bone mass (R 2 = 0.92, p < 0.001), BUA and trabecular number (R 2 = 0.78, p < 0.01) and UV and trabecular bone volume fraction (R 2 = 0.82, p < 0.01). There was only weak, statistically insignificant correlation (R 2 < 0.14, p = 0.21) found between trabecular thickness and any of the ultrasound parameters. The study shows that ultrasound measurements are correlated with bone mass and architecture at the distal radius and, thus, ultrasound may prove useful as a method for noninvasive assessment of osteoporosis and fracture risk. KeywordsOsteoporosis; Ultrasound; Radius; Bone mass; Density; Net time delay; BUA; Peripheral-CT; Velocity Osteoporosis is a significant health problem affecting more than 20 million people in the United States and more than 200 million worldwide (Anonymous 2001). Osteoporosis is defined as the loss of bone mass with a concomitant disruption in microarchitecture, leading to an increased risk of fracture (Kanis 2002 The primary method for diagnosing osteoporosis and associated fracture risk relies on bone densitometry to measure bone mass (Kaufman and Siffert 2001). The use of bone mass is based on the well-established thesis that bone strength is strongly related to the amount of bone material present and that a stronger bone in a given individual is associated generally with a lower fracture risk (Johnell et al. 2005). Radiologic densitometry, which measures the (areal) bone mineral density (BMD) at a given site (e.g., hip, spine, forearm) is currently the accepted "gold standard" indicator of bone strength and fracture risk (Johnell et al. 2005;Blake and Fogelman 2003). Clinically, this is often done using dual energy X-ray absorptiometry (DXA), which measures the BMD in units of g/cm 2 (Blake and Fogelman 2003). Recently, high resolution peripheral-CT imaging has become available for clinical research studies and has led to renewed interest in the distal radius for a better understanding of the relationship betw...

Microarchitecture and bone quality in the human calcaneus: Local variations of fabric anisotropy

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Ultrasonic Assessment of the Radius In Vitro

“…Moreover, since ultrasound is a mechanical wave and interacts with bone in a fundamentally different manner than X-rays, it may be able to provide additional information on bone strength, for example aspects related to trabecular architecture [Siffert and Kaufman, 2007; Haïat et al . 2007; Le Floch et al , 2008]; however the ability of ultrasound to provide such “additional information” has not been clinically established and is at present a somewhat controversial subject [Glüer 2007]. …”

Clinical Assessment of the 1/3 Radius Using a New Desktop Ultrasonic Bone Densitometer

“…The remarkably high degree of similarity in the computational, in vitro and clinical data lends strong support to the applicability of the NTD-based methods used for assessing BMD. Further research on extending ultrasound to assessing the ultra-distal radius is also underway [Le Floch et al, 2008b]. …”

“…, effectively proportional to BMD as would be measured by DXA) in their respective and distinctive pathways. This has been shown for NTD DW using computational, in vitro and clinical studies [Luo et al, 1999; LeFloch et al, 2008a, LeFloch et al, 2008b; Kaufman et al, 2007; Siffert & Kaufman, 2007]. Using geometrical arguments, NTD CW in combination with NTD DW has also been shown in vitro to provide an ultrasonic-based estimate, BMD US , of radial DXA BMD at the 1/3rd location, according to the following formula [LeFloch et al, 2008a]: $${\text{BMD}}_{\text{US}}=a·{false[{\text{NTD}}_{\text{CW}}·{\text{NTD}}_{\text{DW}}false]}^{1/2}+b$$…”