Towards ultrasound computed tomography assessment of bone

This research is a proof of concept study, which focuses on the development and scientific validation of an ultrasound computed tomography (UCT) system with particular emphasis on imaging of bone replica models. Factors that were considered include quantification of complex structure along with tissue properties, such as bone stiffness and cortical shell thickness. For the first time, the concept of ultrasound computed tomography based finite element analysis (UCT-FEA) was investigated. Being non-invasive, non-destructive and non-ionizing, UCT has a significant potential to provide measurement of bone mechanical integrity and improve clinical assessment and management of osteoporosis

Combining Ultrasound Pulse-Echo and Transmission Computed Tomography for Quantitative Imaging the Cortical Shell of Long-Bone Replicas

We demonstrate a simple technique for quantitative ultrasound imaging of the cortical shell of long-bone replicas. Traditional ultrasound computed tomography instruments use the transmitted or reflected waves for separate reconstructions but suffer from strong refraction artifacts in highly heterogeneous samples such as bones in soft tissue. The technique described here simplifies the long bone to a two-component composite and uses both the transmitted and reflected waves for reconstructions, allowing the speed of sound and thickness of the cortical shell to be calculated accurately. The technique is simple to implement, computationally inexpensive, and sample positioning errors are minimal

Estimation of mechanical stiffness by finite element analysis of ultrasound computed tomography (UCT-FEA); a comparison with X-ray µCT based FEA in cancellous bone replica models

The mechanical integrity of a bone is determined by its quantity and quality. Conventional mechanical testing is the ‘gold standard’ for assessing bone strength, although not applicable in vivo since it is inherently invasive and destructive. A mechanical test measurement of stiffness (N mm−1) provides an accurate estimate of strength, although again inappropriate in vivo. Several non-destructive, non-invasive, in vivo techniques have been developed and clinically implemented to serve as surrogates for bone strength assessment including dual-energy X-ray absorptiometry along with axial and peripheral quantitative computed tomography, and quantitative ultrasound. Finite element analysis (FEA) is a computer simulation method that predicts the behaviour of a structure such as a bone under mechanical loading, being previously combined with in vivo bone imaging, reporting higher predictions of mechanical integrity than imaging alone. We hypothesised that ultrasound computed tomography (UCT) may be combined with FEA, thereby predicting the stiffness of bone. The objective of this study was to apply finite element analysis to UCT derived attenuation images of trabecular bone replica samples, thereby providing an estimate of mechanical stiffness that could be compared with both a gold standard mechanical test and a surrogate X-ray µCT-FEA. Replica bone samples were 3D-printed from four anatomical sites (femoral head, lumbar spine, calcaneus and iliac crest), with two cylindrical volumes of interest extracted from each sample. Each replica sample was scanned by X-ray µCT and a bespoke UCT system, from which finite element analysis was performed to estimate mechanical stiffness. The samples were then mechanically tested, yielding the gold standard stiffness value. The coefficient of determination (R2) to estimate mechanical test derived stiffness was 99% for µCT-FEA and 84% for UCT-FEA. In conclusion, UCT-FEA is a promising tool for estimating the mechanical integrity of a bone. This study demonstrated that UCT-FEA, based upon quantitative attenuation images, provided a comparable estimation of gold standard mechanical-test stiffness and therefore has significant potential clinical utility for osteoporotic fracture risk assessment and quantitative assessment of musculoskeletal tissues

The Effect of Plasticizers on the Polypyrrole-Poly(vinyl alcohol)-Based Conducting Polymer Electrolyte and Its Application in Semi-Transparent Dye-Sensitized Solar Cells

In this work, the quasi-solid-state polymer electrolyte containing poly(vinyl alcohol)-polypyrrole as a polymer host, potassium iodide (KI), iodine (I2), and different plasticizers (EC, PC, GBL, and DBP) was successfully prepared via the solution casting technique. Fourier transform infrared spectroscopy (FTIR) was used to analyze the interaction between the polymer and the plasticizer. X-ray diffraction confirmed the reduction of crystallinity in the polymer electrolyte by plasticizer doping. The ethylene carbonate-based polymer electrolyte showed maximum electrical conductivity of 0.496 S cm−1. The lowest activation energy of 0.863 kJ mol−1 was obtained for the EC-doped polymer electrolyte. The lowest charge transfer resistance Rct1 was due to a faster charge transfer at the counter electrode/electrolyte interface. The polymer electrolyte containing the EC plasticizer exhibited an average roughness of 23.918 nm. A photo-conversion efficiency of 4.19% was recorded in the DSSC with the EC-doped polymer electrolyte under the illumination of 100 mWcm−2

Additional file 1 of Biological quality and phytochemical profiling of olive fruits using gas chromatography–mass spectrometry (GCMS) analysis

Additional file 1. Supplementary file for the GCMS profile of 42-olive samples