Broadband Ultrasonic Attenuation Research Articles

Are Children Suffering From Congenital Pseudarthrosis of the Tibia Associated With Decreased Bone Strength?

Background:Congenital pseudarthrosis of the tibia (CPT) is a rare and difficult-to-treat congenital disease in neonates. Our previous study found that exosomes derived from serum of children with CPT inhibit bone formation. In this study, we used ultrasound bone densitometry to detect the bone strength differences between hospitalized children with CPT and with non-metabolic diseases to determine the bone strength of children with CPT.MethodsA total of 37 children with CPT with a mean age of 3.14 ± 1.81 years and 40 hospitalized children with a mean age of 3.32 ± 2.66 years with supracondylar fracture of the humerus and without a bone metabolic disease (control group) were recruited in our hospital. The ultrasonic bone densitometer was used to examine the bilateral calcaneus of the subjects. We collected the broadband ultrasonic attenuation (BUA), speed of sound (SOS), quantitative ultrasound index (QUI), bone strength index (STI) and bone mineral density estimation (BMDe) values. Multivariable regression was used to examine the associations between quantitative ultrasound measurement differences and age, body mass index (BMI), neurofibromatosis type 1 (NF1) and CPT Crawford type. Intra-class correlation coefficient (ICC) was calculated to estimate intra- and inter-rater agreements.Results74 calcaneus scans were taken from CPT patients (23 boys and 14 girls) and 80 calcaneus scans were taken from the control (24 boys and 16 girls). The CPT patients exhibited significantly lower SOS (1,368.75 ± 136.78 m/s), STI (7.2319 ± 38.6525), QUI (8.2532 ± 56.1720), and BMDe (−0.0241 ± 0.3552 g/cm3) than the control (SOS: 1,416.02 ± 66.15 m/s, STI: 7.96 ± 16.884, QUI: 28.8299 ± 25.461, BMDe: 0.0180 ± 0.1610 g/cm3). Multiple regression revealed that SOS, STI and QUI were statistically significant and negatively correlated with CPT Crawford classification.ConclusionsWe found the incidence of decreased bone strength in CPT group was higher than that in the non-bone metabolic disease group. This phenomenon was not related to NF1 but related to CPT Crawford classification, which suggested that the higher the grade of the CPT Crawford classification, the lower the bone strength and the higher the risk of fracture.

In vivo pulse-echo measurement of apparent broadband attenuation and Q factor in cortical bone: a preliminary study

Quantitative ultrasound (QUS) methods have been introduced to assess cortical bone health at the radius and tibia through the assessment of cortical thickness (Ct.Th), cortical porosity and bulk wave velocities. Ultrasonic attenuation is another QUS parameter which is not currently used. We assessed the feasibility of in vivo measurement of ultrasonic attenuation in cortical bone with a broadband transducer with 3.5 MHz center frequency. Echoes from the periosteal and endosteal interfaces were fitted with Gaussian pulses using sparse signal processing. Then, the slope of the broadband ultrasonic attenuation (Ct.nBUA) in cortical bone and quality factor were calculated with a parametric approach based on the center-frequency shift. Five human subjects were measured at the one-third distal radius with pulse-echo ultrasound, and reference data was obtained with high-resolution x-ray peripheral computed tomography (Ct.Th and cortical volumetric bone mineral density (Ct.vBMD)). Ct.Th was used in the calculation of Ct.nBUA while is obtained solely from ultrasound data. The values of Ct.nBUA (6.7 ± 2.2 dB MHz−1 .cm−1) and (8.6 ± 3.1%) were consistent with the literature data and were correlated to Ct.vBMD (, , RMSE = 0.56 dB.MHz−1.cm−1, and , , RMSE = 0.76%). This preliminary study suggests that the attenuation of an ultrasound signal propagating in cortical bone can be measured in vivo at the one-third distal radius and that it provides an information on bone quality as attenuation values were correlated to Ct.vBMD. It remains to ascertain that Ct.nBUA and measured here exactly reflect the true (intrinsic) ultrasonic attenuation in cortical bone. Measurement of attenuation may be considered useful for assessing bone health combined with the measurement of Ct.Th, porosity and bulk wave velocities in multimodal cortical bone QUS methods.

Determination of Cutoff Values for the Screening of Osteosarcopenia in Obese Postmenopausal Women

Osteosarcopenic obesity (OSO) describes the concurrent presence of obesity, low bone mass, and low muscle mass in an individual. Currently, no established criteria exist to diagnose OSO. We hypothesized that obese individuals require different cut-points from standard cut-points to define low bone mass and low muscle mass due to their higher weight load. In this study, we determined cutoff values for the screening of osteosarcopenia (OS) in obese postmenopausal Malaysian women based on the measurements of quantitative ultrasound (QUS), bioelectrical impedance analysis (BIA), and functional performance test. Then, we compared the cutoff values derived by 3 different statistical modeling methods, (1) receiver operating characteristic (ROC) curve, (2) lowest quintile of the study population, and (3) 2 standard deviations (SD) below the mean value of a young reference group, and discussed the most suitable method to screen for the presence of OS in obese population. One hundred and forty-one (n = 141) postmenopausal Malaysian women participated in the study. Bone density was assessed using calcaneal quantitative ultrasound. Body composition was assessed using bioelectrical impedance analyzer. Handgrip strength was assessed using a handgrip dynamometer, and physical performance was assessed using a modified Short Physical Performance Battery test. ROC curve was determined to be the most suitable statistical modeling method to derive the cutoffs for the presence of OS in obese population. From the ROC curve method, the final model to estimate the probability of OS in obese postmenopausal women is comprised of five variables: handgrip strength (HGS, with area under the curve (AUC) = 0.698 and threshold ≤ 16.5 kg), skeletal muscle mass index (SMMI, AUC = 0.966 and threshold ≤ 8.2 kg/m2), fat-free mass index (FFMI, AUC = 0.946 and threshold ≤ 15.2 kg/m2), broadband ultrasonic attenuation (BUA, AUC = 0.987 and threshold ≤ 52.85 dB/MHz), and speed of sound (SOS, AUC = 0.991 and threshold ≤ 1492.15 m/s). Portable equipment may be used to screen for OS in obese women. Early identification of OS can help lower the risk of advanced functional impairment that can lead to physical disability in obese postmenopausal women.

The inverse association between parity and bone health is independent of lifestyle in postmenopausal Chinese women.

This study aimed to investigate the association between parity and bone mineral density in postmenopausal Chinese women, as well as the interference of physical activity and sedentary time on this association. A total of 1,712 participants were enrolled in this study. Participants were separated into three groups according to the number of parities: group 1, 1-2; group 2, 3-4; group 3, ≥5. Physical activity level was assessed according to the International Physical Activity Questionnaire. Calcaneus bone mineral density (BMD) and bone quality were assessed by qualitative ultrasound. As a result, logistic regression showed that compared to that in group 1, the risk of fracture in group 3 was increased significantly (p < 0.001). A greater number of parities was associated with a lower BMD, broadband ultrasonic attenuation (BUA), quantitative ultrasound index (QUI), speed of sound (SOS), and T-score among the three groups after adjustment for age (All p for trend < 0.05). The number of parities was an independent factor negatively correlated with BMD, BUA, QUI, SOS and T-score (All p < 0.05). BMD, BUA, QUI, SOS, and T-score were significantly increased in the physically a participants independent of parity (all p < 0.05), and decreased in the sedentary participants independent of parity (p < 0.05, except BUA). A great number of parities was negatively associated with bone health. Physical activity was positively correlated and sedentary time was negatively correlated with bone health independent of parity.

Exposure to Famine in Early Life and the Risk of Osteoporosis in Adulthood: a Prospective Study

Objective: To assess the association between famine exposure in early life and osteoporosis in adulthood. Methods: A total of 2,292 participants born between 1955 and 1965 in Fujian Province were selected; after 3 years, 1,378 participants attended a follow-up research visit. Calcaneus bone mineral density and bone quality were measured by quantitative ultrasound. The T-score was used to assess bone mineral density, and the parameters quantitative ultrasound index (QUI), speed of sound (SOS), and broadband ultrasonic attenuation (BUA) were used to assess bone quality. A T-score threshold of -1.8 was defined as osteoporosis, and a possible vertebral fracture was considered as a prospective height loss of 0.8 inches or more. Results: Compared with the nonexposed cohort, risks of osteoporosis for fetal-, early childhood, and mid-childhood famine-exposed cohorts in postmenopausal women were adjusted odds ratio (OR), 3.741 (95% confidence interval [CI], 1.233, 11.44) versus OR 2.894 (95% CI, 0.997, 8.571) versus OR 4.699 (95% CI, 1.622, 13.612) by logistic regression but not significant in men. Moreover, the fetal-exposed cohort had a weak negative relation with QUI (β, -5.07 [-10.226, 0.127]) and BUA (β, -4.321 [-0.88, 0.238]). The early- and mid-childhood-exposed cohorts had significantly lower QUI (β, -7.085 [-11.799, -2.372] versus β, -10.845 [-15.68, -6.01]) and BUA (β, -6.381 [-10.515, -2.246] versus β, -8.573 [-12.815, -4.331]) than the nonexposed cohort by linear regression. None of the famine-exposed cohorts had a significant relationship with SOS. Conclusion: Famine exposure during early life is associated with higher risk of osteoporosis in adulthood, which is most obvious in postmenopausal women. Furthermore, famine exposure in early life has adverse effects on bone quality. Abbreviations: BMD = bone mineral density; BUA = broadband ultrasonic attenuation; CI = confidence interval; OR = odds ratio; QUI = quantitative ultrasound index; QUS = quantitative ultrasound; SOS = speed of sound.

Broadband Ultrasonic Attenuation Estimation and Compensation With Passive Acoustic Mapping.

Several active and passive techniques have been developed to detect, localize, and quantify cavitation activity during therapeutic ultrasound procedures. Much of the prior cavitation monitoring research has been conducted using lossless in vitro systems or small animal models in which path attenuation effects were minimal. However, the performance of these techniques may be substantially degraded by attenuation between the internal therapeutic target and the external monitoring system. As a further step toward clinical application of passive acoustic mapping (PAM), this paper presents methods for attenuation estimation and compensation based on broadband cavitation data measured with a linear ultrasound array. Soft tissue phantom experiment results are used to illustrate: 1) the impact of realistic attenuation on PAM; 2) the possibility of estimating attenuation from cavitation data; 3) cavitation source energy estimation following attenuation compensation; and 4) the impact of sound speed uncertainty on PAM-related processing. Cavitation-based estimates of attenuation were within 1.5%-6.2% of the values found from conventional through-transmission measurements. Tissue phantom attenuation reduced the PAM energy estimate by an order of magnitude, but array data compensation using the cavitation-based attenuation spectrum enabled recovery of the PAM energy estimate to within 2.9%-5.9% of the values computed in the absence of the phantom. Sound speed uncertainties were found to modestly impact attenuation-compensated PAM energies, inducing errors no larger than 28% for a 40-m/s path-averaged speed error. Together, the results indicate the potential to significantly enhance the quantitative capabilities of PAM for ensuring therapeutic safety and efficacy.

Characterization of ultrasound attenuation and angular distribution from trabecular bone phantom material using refracto-vibrometry

Ultrasound is being researched and used for diagnosing osteoporosis. Researchers use trabecular bone from humans as a test material, but such bone is bio-hazardous, not uniform, and of limited size. Recently it has been demonstrated that the open-cell polyurethane foam, known as “Sawbones” could be utilized as a substitute for trabecular bone in ultrasound studies. In the current study, rectangular slices of Sawbones trabecular bone phantom material were insonified with a 25 mm diameter 500 kHz ultrasound transducer oriented both normal to the surface and at an angle. Refracto-vibrometry (RV), an interferometric method for optically measuring ultrasound, was compared with conventional transducer measurements of ultrasound transmission through the bone phantom samples. The measurement beam from a Polytec PSV-400 scanning laser Doppler vibrometer was directed through a water tank towards a stationary retroreflective surface. Acoustic wave fronts (density variations) which pass through the ~50µm diameter measurement laser cause variations in the integrated optical path length. The measured signals were used to determine parameters such as normalized broadband ultrasonic attenuation (nBUA) at numerous scan points. This enabled measurements of the spatial and angular distribution of the transmitted ultrasonic field through the sample that are not possible using a conventional single-element ultrasonic transducer.

Characterization of a polymer, open-cell rigid foam that simulates the ultrasonic properties of cancellous bone.

Materials that simulate the ultrasonic properties of tissues are used widely for clinical and research purposes. However, relatively few materials are known to simulate the ultrasonic properties of cancellous bone. The goal of the present study was to investigate the suitability of using a polymer, open-cell rigid foam (OCRF) produced by Sawbones®. Measurements were performed on OCRF specimens with four different densities. Ultrasonic speed of sound and normalized broadband ultrasonic attenuation were measured with a 0.5 MHz transducer. Three backscatter parameters were measured with a 5 MHz transducer: apparent integrated backscatter, frequency slope of apparent backscatter, and normalized mean of the backscatter difference. X-ray micro-computed tomography was used to measure the microstructural characteristics of the OCRF specimens. The trabecular thickness and relative bone volume of the OCRF specimens were similar to those of human cancellous bone, but the trabecular separation was greater. In most cases, the ultrasonic properties of the OCRF specimens were similar to values reported in the literature for cancellous bone, including dependence on density. In addition, the OCRF specimens exhibited an ultrasonic anisotropy similar to that reported for cancellous bone.

Attempt at standardization of bone quantitative ultrasound in Japan.

Dual X-ray absorptiometry (DXA) is used to diagnose osteoporosis. On the other hand, quantitative ultrasound (QUS) is widely used to assess bone density as part of medical screening as it is relatively inexpensive and easy to perform. Current QUS devices do not share precise ultrasound-related parameters, such as frequency, waveform, beam pattern, transient response, definition of propagation time, definition of degree of attenuation, and precise measurement site, resulting in different measurements across models. The Japan Osteoporosis Society established a QUS Standardization Committee in 2007 to investigate standardization of speed of sound (SOS) and broadband ultrasonic attenuation (BUA) measurements to resolve this issue. The committee came up with a formula to convert SOS and BUA values yielded by each model available in Japan. This has made it possible to convert QUS measurements from different models into standardized values, greatly improving the effectiveness of QUS measurements.

Three-dimensional Simulation of Quantitative Ultrasound in Cancellous Bone Using the Echographic Response of a Metallic Pin.

Degenerative discopathy is a common pathology that may require spine surgery. A metallic cylindrical pin is inserted into the vertebral body to maintain soft tissues and may be used as a reflector of ultrasonic wave to estimate bone density. The first aim of this paper is to validate a three-dimensional (3-D) model to simulate the ultrasonic propagation in a trabecular bone sample in which a metallic pin has been inserted. We also aim at determining the effect of changes of bone volume fraction (BV/TV) and of positioning errors on the quantitative ultrasound (QUS) parameters in this specific configuration. The approach consists in coupling finite-difference time-domain simulation with X-ray microcomputed tomography. The correlation coefficient between experimental and simulated speed of sound (SOS)-respectively, broadband ultrasonic attenuation (BUA)-was equal to 0.90 (respectively, 0.55). The results show a significant correlation of SOS with BV/TV ( R = 0.82), while BUA values exhibit a nonlinear behavior versus BV/TV. The orientation of the pin should be controlled with an accuracy of around 1° to obtain accurate results. The results indicate that using the ultrasonic wave reflected by a pin has a potential to estimate the bone density. SOS is more reliable than BUA due to its lower sensitivity to the tilt angle.

Phase cancellation effect on broadband ultrasonic attenuation analysis for human trabecular bone assessment using a 2-D synthetic array

Quantitative ultrasound has been developed to evaluate trabecular BMD and structural integrity. The ultrasound parameters, i.e., normalized broadband attenuation (nBUA), have been widely used for bone health status. However, the reproducibility and accuracy of nBUA are influenced by the phenomena of phase cancellation. The objectives of this study have two folds, 1) to accurately investigate the effects of phase cancellation on BUA calculation using an ultra-small receiver (aperture size: 0.2 mm) in a newly developed 2-D synthetic array-system, and 2) to evaluate the effects of phase cancellation on human trabecular bones. Most energy was located within a circle with a diameter of 12.70 mm corresponding to the transmitter aperture size. The tests of ultrasound BUA and micro-CT on the trabecular bone cylinders with a diameter of 25 mm. Both phase sensitive (PS) detection and phase insensitive (PI) detections were performed. The data indicated that the average nBUA is 24.8±9.5 dB/MHz/cm and 19.2±5.5 dB/MHz/...

Quantitative ultrasound measurements in trabecular bone using the echographic response of a metallic pin: Application to spine surgery

Bone quality is an important parameter in spine surgery, but it remains difficult to be assessed clinically. The aim of this work is to demonstrate the feasibility of a QUS method to retrieve bone mechanical properties using an echographic technique taking advantage of the presence of a metallic pin inserted in bone tissue. To do so, an experimental validation is performed and acoustical modeling is used in order to assess the influence of experimental errors. A metallic pin was inserted in bone tissue perpendicularly to the transducer axis. The echographic response of the bone sample was determined and the echoes of the pin inserted in bone tissue and in water were compared to determine speed of sound (SOS) and broadband ultrasonic attenuation (BUA), which was compared to bone volume fraction (BV/TV). A 2-D finite element model was developed to assess the effect of positioning errors. Moreover, the coupling of finite difference time domain simulation with high resolution imaging technique was used to understand the interaction between an ultrasonic wave and the bone microstructure. A significant correlation between SOS and BV/TV was found (R² = 0.6). The numerical results show the relative robustness of the measurement method, which could be useful to estimate bone quality intraoperatively.

Predictive ability of heel quantitative ultrasound for incident fractures: an individual-level meta-analysis.

The relationship between bone quantitative ultrasound (QUS) and fracture risk was estimated in an individual level data meta-analysis of 9 prospective studies of 46,124 individuals and 3018 incident fractures. Low QUS is associated with an increase in fracture risk, including hip fracture. The association with osteoporotic fracture decreases with time. The aim of this meta-analysis was to investigate the association between parameters of QUS and risk of fracture. In an individual-level analysis, we studied participants in nine prospective cohorts from Asia, Europe and North America. Heel broadband ultrasonic attenuation (BUA dB/MHz) and speed of sound (SOS m/s) were measured at baseline. Fractures during follow-up were collected by self-report and in some cohorts confirmed by radiography. An extension of Poisson regression was used to examine the gradient of risk (GR, hazard ratio per 1 SD decrease) between QUS and fracture risk adjusted for age and time since baseline in each cohort. Interactions between QUS and age and time since baseline were explored. Baseline measurements were available in 46,124 men and women, mean age 70 years (range 20-100). Three thousand and eighteen osteoporotic fractures (787 hip fractures) occurred during follow-up of 214,000 person-years. The summary GR for osteoporotic fracture was similar for both BUA (1.45, 95 % confidence intervals (CI) 1.40-1.51) and SOS (1.42, 95 % CI 1.36-1.47). For hip fracture, the respective GRs were 1.69 (95 % CI, 1.56-1.82) and 1.60 (95 % CI, 1.48-1.72). However, the GR was significantly higher for both fracture outcomes at lower baseline BUA and SOS (p < 0.001). The predictive value of QUS was the same for men and women and for all ages (p > 0.20), but the predictive value of both BUA and SOS for osteoporotic fracture decreased with time (p = 0.018 and p = 0.010, respectively). For example, the GR of BUA for osteoporotic fracture, adjusted for age, was 1.51 (95 % CI 1.42-1.61) at 1 year after baseline, but at 5 years, it was 1.36 (95 % CI 1.27-1.46). Our results confirm that quantitative ultrasound is an independent predictor of fracture for men and women particularly at low QUS values.

Broadband ultrasonic spectrometry of polystyrene-cyclohexane critical mixtures

Mutual diffusion coefficients, shear viscosities, and broadband ultrasonic attenuation spectra in the frequency range 100 kHz to 300 MHz have been measured for solutions of polystyrene in cyclohexane at two degrees of polymerization N and various temperatures near the critical. The exponent y(η) in the power law representation of the critical part in the viscosity deviates substantially from the universal value y(η) = 0.0435: y(η) = 0.028 (N = 288) and y(η) = 0.014 (N = 6242). Also, the adiabatic coupling constant g and the amplitudes ξ(0) and Γ(0) in the power laws of the correlation length and the relaxation rate of fluctuations, respectively, depend on N. This is especially obvious with the relaxation rates, for which Γ(0) = 5.8×10(9) at N = 288 and Γ(0) = 6.1×10(7) with the larger polymer results. A noteworthy feature is the difference between the relaxation rates from the diffusion coefficients and shear viscosities on the one hand and from the ultrasonic spectra on the other. Near the critical temperatures the latter Γ values deviate from power law behavior, indicating a coupling between the concentration fluctuations and structural isomerizations of the polymers.

WE‐E‐134‐05: Noncontact Ultrasound Applied to Osteroporosis Diagnostics Updated to Include Broadband Ultrasonic Attenuation and Offline Data Analysis

Purpose: The purpose was to push forward our efforts on applying noncontact ultrasound to quantitative imaging of cortical bone as described in our recent paper on speed of sound and attenuation, and integrated response to ultrasound spectroscopy including Broadband ultrasound attenuation (BUA) and to replace our noisy piezoelectric transducers with much quieter velocity correcting capacitive transducers at frequencies of 500 kHz and 850kHz. Methods: An NCU imaging system, a pair of broadband capacitive .500 and .850 MHz, non‐contact transducers, and cortical bone phantoms were used to determine bone mineral density (BMD), speed of sound (SOS), integrated acoustical response (IR), and ultrasonic transmittance. Air gaps of greater than 3 cm, two transmission and reflection paths, and a digital signal processor were used to collect data from phantoms of nominal mass density and (BMD) from 1.17 g/cm3 to 2.25 g/cm3 and from 0 g/cm3 to 1.7 g/cm3. Spectra were analyzed offline using Matlab, including its signal processing and Simulink tool boxes as well as customized Matlab based files, therefore providing much more detailed methods then online approaches, as used in our initial paper. Results: Good correlations between known BMD and measured SOS, IR, and transmittance were obtained for all 14 phantoms obtained in the original studies were complimented with spectroscopic and BUA measurements obtained with capacitive transducers that had much better stability then the original measurements and provided strong correlations with the known BMD of phantoms. Conclusion: The results suggest that the usage of capacitive transducers, offline analysis with Matlab including customized simulations and data analysis algorithms yields much better results than those in our original paper. The new results give us all the more impetus to extend the NCU methods to bone phantoms that more closely mimic human cortical bone and to subsequently apply our methods in vivo.

Prediction of trabecular bone qualitative properties using scanning quantitative ultrasound

Microgravity induced bone loss represents a critical health problem in astronauts, particularly occurred in weight-supporting skeleton, which leads to osteopenia and increase of fracture risk. Lack of suitable evaluation modality makes it difficult for monitoring skeletal status in long term space mission and increases potential risk of complication. Such disuse osteopenia and osteoporosis compromise trabecular bone density, and architectural and mechanical properties. While X-ray based imaging would not be practical in space, quantitative ultrasound may provide advantages to characterize bone density and strength through wave propagation in complex trabecular structure. This study used a scanning confocal acoustic diagnostic and navigation system (SCAN) to evaluate trabecular bone quality in 60 cubic trabecular samples harvested from adult sheep. Ultrasound image based SCAN measurements in structural and strength properties were validated by μCT and compressive mechanical testing. This result indicated a moderately strong negative correlations observed between broadband ultrasonic attenuation (BUA) and μCT-determined bone volume fraction (BV/TV, R2=0.53). Strong correlations were observed between ultrasound velocity (UV) and bone's mechanical strength and structural parameters, i.e., bulk Young's modulus (R2=0.67) and BV/TV (R2=0.85). The predictions for bone density and mechanical strength were significantly improved by using a linear combination of both BUA and UV, yielding R2=0.92 for BV/TV and R2=0.71 for bulk Young's modulus. These results imply that quantitative ultrasound can characterize trabecular structural and mechanical properties through measurements of particular ultrasound parameters, and potentially provide an excellent estimation for bone's structural integrity.

Association of MMP14 gene polymorphisms and osteoporosis in Zhuang men from Baise region of Guangxi

To assess the association between membrane type 1 matrix metalloproteinase gene (MT1-MMP, MMP14) polymorphisms and osteoporosis in Zhuang men from Baise region of Guangxi. Genotypes of 5 loci (rs1003349, rs3751488, rs2269213, rs2236303 and rs743257) of MMP14 gene in 301 Zhuang men were determined with single base extension methods, and bone mineral density (BMD) at left calcaneus was evaluated with quantitative ultrasound with measured values of broadband ultrasonic attenuation (BUA). The subjects were divided according to BMD into osteoporosis group, osteopenia group and normal bone density group. All selected loci were in Hardy-Weinberg equilibrium (P> 0.05). By multiple linear stepwise regression analysis, polymorphisms of the five loci were not associated with BUA. But a significant higher risk of osteoporosis was found in individuals with MMP14 rs1003349 GT genotype (vs. GG genotype; P<0.05) and rs2236303 CC and CT genotypes (vs. TT genotype; P<0.05). Genetic linkage between rs1003349 and rs2236303 was also discovered (D'= 0.839, r(2) = 0.458, P<0.01). Compared with the normal bone density group, the frequency of a G-T haplotype of rs1003349 and rs2236303 was significantly lower in the osteoporosis group (P<0.05). And the risk of osteoporosis for individuals with G-C and T-C haplotypes was 2.556 (95% CI: 1.029-6.349, P = 0.038) and 5.111 (95% CI: 1.341-19.485, P = 0.011) compared with G-T haplotype. Polymorphisms of rs1003349 and rs2236303 loci of MMP14 gene are associated with the susceptibility of osteoporosis in Zhuang men in Guangxi. G-C and T-C haplotypes for loci rs1003349 and rs2236303 may increase the disease risk.

Correlation of ultrasonic backscatter parameters with transmission parameters and BMD in cancellous bone

Quantitative ultrasound (QUS) has been suggested to have a performance equal to dual-energy X-ray absorptiometry (DXA) for the assessment of bone. In this paper, human cancellous bone is investigated in vivo using QUS and DXA. The ultrasonic backscatter method and its parameters (spectral centroid shift (SCS), apparent integrated backscatter (AIB)) are also introduced. The experimental ultrasonic backscatter signals are collected from 300 volunteers' calcanea in two hospitals, and the two parameters are calculated. Finally, correlation between ultrasonic backscatter parameters and transmission parameters (speed of sound (SOS), broadband ultrasonic attenuation (BUA) and stiffness index (SI)), as well as correlation between backscatter parameters and bone material density (BMD) are analyzed. The results showed that correlations between backscatter parameters and SI are better than that of SOS and BUA. SI correlates positively with SCS (r=0.613, p&amp;lt;0.05), as well with AIB (r=0.463, p&amp;lt;0.05). According to the size of SCS and AIB of ultrasonic backscattered signals, the status of cancellous bone may be assessed.

Cholesterol-Induced Variations in the Domain Structure Fluctuations and Microdynamics of Lipid Membranes

Broadband ultrasonic attenuation spectra (100 kHz to 2 GHz) of aqueous solutions of vesicles from 1,2-dimyristoyl-l-3-phosphatidylcholine, with different amounts of cholesterol admixed, have been measured at temperatures between 20 and 28 °C. The spectra have been evaluated in terms of suitable relaxation functions. They are discussed in view of the effect of cholesterol on the membrane behavior around the gel-fluid phase transition temperature T(m). In addition to a frequency-independent asymptotic high-frequency term, all spectra reveal a critical term and a Debye-type relaxation term with relaxation time around 0.5 ns. The former is evaluated in the light of the Bhattacharjee-Ferrell dynamic scaling theory. It is assigned to the critical domain structure fluctuations of the membranes. Critical slowing of fluctuations is demonstrated. Also shown are relations of the critical amplitudes to thermodynamic parameters. The Debye term reflects the rotational isomerization of the phospholipid alkyl chains. The relaxation time of isomerization reveals a significant steplike change at T(m). At moderate cholesterol content an additional Debye relaxation term exists. It is assigned to the axial diffusion of the membrane molecules. Because it likewise shows effects of slowing near T(m), the diffusion appears to be coupled to the domain structure fluctuations. A further relaxation term at small cholesterol concentration is assumed to be due to small-range shape fluctuations of vesicles near the phase transition temperature.

Effects of Phase Cancellation and Receiver Aperture Size on Broadband Ultrasonic Attenuation for Trabecular Bone In Vitro

Phase cancellation in ultrasound due to large receiver size has been proposed as a contributing factor to the inaccuracy of estimating broadband ultrasound attenuation (BUA), which is used to characterize bone quality. Transducers with aperture size ranging from 2 to 5 mm have been used in previous attempts to study the effect of phase cancellation. However, these receivers themselves are susceptible to phase cancellation because aperture size is close to one center wavelength (about 3 mm at 500 KHz in water). This study uses an ultra small receiver (aperture size: 0.2 mm) in conjunction with a newly developed two-dimensional (2-D) synthetic array system to investigate the effects of phase cancellation and receiver aperture size on BUA estimations of bone tissue. In vitro ultrasound measurements were conducted on 54 trabecular bone samples (harvested from sheep femurs) in a confocal configuration with a focused transmitter and synthesized focused receivers of different aperture sizes. Phase sensitive (PS) and phase insensitive (PI) detections were performed. The results show that phase cancellation does have a significant effect on BUA. The normalized BUA (nBUA) with PS is 8.1% higher than PI nBUA while PI BUA is well correlated with PS BUA. Receiver aperture size also influences the BUA reading for both PI and PS detection and smaller receiver aperture tends to result in higher BUA readings. The results also indicate that the receiver aperture size used in the confocal configuration with PI detection should at least equal the aperture of the transmitter to capture most of the energy redistributed by the interference and diffraction from the trabecular bone.