Ultrasonic backscatter techniques are being developed to detect changes in bone caused by osteoporosis. The present study introduces a new technique that measures the exponential decay in the amplitude of the backscatter signal quantified by a parameter called the backscatter amplitude decay constant (BADC). Measurements were performed on 54 specimens of cancellous bone from 14 human femurs using a 3.5-MHz transducer. Six methods were tested to determine BADC. The recommended method measures the time slope of the natural log of the rectified signal. Measured values of BADC ranged from approximately 0.1 μs to 0.6 μs. Moderate to strong correlations (Spearman's ρ >0.7) were found between BADC and the density and microstructural characteristics of the specimens determined using X-ray microcomputed tomography. The results of this study suggest that BADC may be able to detect changes in the density and microstructure of cancellous bone caused by osteoporosis and other diseases.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.ultrasmedbio.2020.04.029 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Dynamic control of the directional scattering of single Mie particle by laser induced metal insulator transitions.
Nanophotonics
August 2024
Key Laboratory of Optoelectronic Technology & Systems, Ministry of Education, and College of Optoelectronic Engineering, Chongqing University, Chongqing 400044, China.
Interference between the electric and magnetic dipole-induced in Mie nanostructures has been widely demonstrated to tailor the scattering field, which was commonly used in optical nano-antennas, filters, and routers. The dynamic control of scattering fields based on dielectric nanostructures is interesting for fundamental research and important for practical applications. Here, it is shown theoretically that the amplitude of the electric and magnetic dipoles induced in a vanadium dioxide nanosphere can be manipulated by using laser-induced metal-insulator transitions, and it is experimentally demonstrated that the directional scattering can be controlled by simply varying the irradiances of the excitation laser.
View Article and Find Full Text PDFA detailed protocol for measuring the complex forward-scattering amplitude S(0°) of single particles, the Complex Amplitude Sensing version 1 (CAS-v1), has recently been developed and used for characterizing environmental particles. However, interpretations of the S(0°) data need a priori assumptions on the particle's shape, and applications of the method have mostly been limited to the particles suspended in liquids. Here, we thoroughly upgrade the CAS technique to perform quality-controlled S(0°) measurements at two independent polarizations for particles suspended in gases and liquids.
View Article and Find Full Text PDFFrequency modulation of narrow-linewidth lasers can cause coherent backscattering in cladding-pumped fiber amplifiers. This detrimental effect can be observed in Tm-based fiber amplifiers and can be an additional limitation for power scaling applications. We investigate such instabilities in Tm- and Tm/Ho-doped fiber amplifiers for a wide range of design parameters (active fiber length, pumping scheme, dopant type) and operation regimes (laser frequency tuning rate, amplifier gain).
View Article and Find Full Text PDFHarmonic imaging for nonlinear detection of acoustic biomolecules.
APL Bioeng
December 2024
Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, California 91125, USA.
Gas vesicles (GVs) based on acoustic reporter genes have emerged as potent contrast agents for cellular and molecular ultrasound imaging. These air-filled, genetically encoded protein nanostructures can be expressed in a variety of cell types to visualize cell location and activity or injected systemically to label and monitor tissue function. Distinguishing GV signal from tissue deep inside intact organisms requires imaging approaches such as amplitude modulation (AM) or collapse-based pulse sequences.
View Article and Find Full Text PDFArticle Synopsis
- Multi-core fiber (MCF) is gaining attention for distributed fiber sensing because it can transmit light independently through multiple channels, reducing issues like coherent fading that affect signal quality.
- A new method called spatial rotated-vector-average (SRVA) combines signals from these channels to effectively minimize phase noise and prevent errors in signal processing.
- Experiments with a 2.58-km MCF demonstrated a significant reduction in fading and noise levels, leading to improved localization accuracy and reliable signal recovery, which enhances the use of MCF in long-distance sensing applications.
Want AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!