Daniel Patterson Matusin

Ultrasound method applied to characterize healthy femoral diaphysis of Wistar rats in vivo.

A simple experimental protocol applying a quantitative ultrasound (QUS) pulse-echo technique was used to measure the acoustic parameters of healthy femoral diaphyses of Wistar rats in vivo. Five quantitative parameters [apparent integrated backscatter (AIB), frequency slope of apparent backscatter (FSAB), time slope of apparent backscatter (TSAB), integrated reflection coefficient (IRC), and frequency slope of integrated reflection (FSIR)] were calculated using the echoes from cortical and trabecular bone in the femurs of 14 Wistar rats. Signal acquisition was performed three times in each rat, with the ultrasound signal acquired along the femurs central region from three positions 1 mm apart from each other. The parameters estimated for the three positions were averaged to represent the femur diaphysis. The results showed that AIB, FSAB, TSAB, and IRC values were statistically similar, but the FSIR values from Experiments 1 and 3 were different. Furthermore, Pearsons correlation coefficient showed, in general, strong correlations among the parameters. The proposed protocol and calculated parameters demonstrated the potential to characterize the femur diaphysis of rats in vivo. The results are relevant because rats have a bone structure very similar to humans, and thus are an important step toward preclinical trials and subsequent application of QUS in humans.

In vivo characterization of long-bone in animal model by two ultrasonic scattering parameters: AIB and FSAB

Quantitative Ultrasound (QUS) is a new possibility for non-ionizing diagnosis and monitoring of bone diseases which are usually monitored by radiographs. In this work, an ultrasound (US) pulse-echo method was proposed to in vivo signal acquisition for long bone characterization in an animal model. Two parameters, one related to US backscattering from bone and the other to US reflection at the muscle/bone interface, were calculated in both femurs of seven rats and the results showed that their values statistically belong to the same group. This is indication that the proposed protocol has potential to characterize normal in vivo long bones in animal models.

Characterization of pseudarthrosis with ultrasound backscattered signals in rats

PURPOSE To propose a novel model of pseudarthrosis in a small animal and to investigate the ability of backscatter parameters from ultrasound signals in differentiating normal bone from those ones with pseudarthrosis. METHODS Twelve Rattus norvegicus albinus free from pathogenic species (SPF) were randomly divided in two groups, with six animals each. In the Control group a surgical approach to the femur was made, followed by the synthesis of the muscle and skin layers. The Experimental group was submitted to an osteotomy of the femur and a vascularized flap of the fascia lata was interposed in the line of the fractured bone. Then the alignment and bone stabilization were accomplished, by using nylon stitch in U shape introduced in holes made in the proximal and distal fractured bone. Bone samples were scanned with ultrasound and signals were collected for each one to analyze the parameter Apparent Integrated Backscatter - AIB. RESULTS Radiological and anatomopathologic studies revealed the absence of bone consolidation with persistence of fiber-osteoid tissue. Values of the ultrasound parameter AIB from normal bones were statistically different from those with pseudarthrosis. CONCLUSION The experimental model was suitable for pseudarthrosis development in rats and the ultrasound backscatter parameters were able to identify such a bone disease in vitro.

Monitoring bone changes due to calcium, magnesium, and phosphorus loss in rat femurs using Quantitative Ultrasound

Bone mineral density is an important parameter for the diagnosis of bone diseases, as well as for predicting fractures and treatment monitoring. Thus, the aim of the present study was to evaluate the potential of Quantitative Ultrasound (QUS) to monitor bone changes after calcium, phosphorus, and magnesium loss in rat femurs in vitro during a demineralization process. Four quantitative ultrasound parameters were estimated from bone surface echoes in eight femur diaphysis of rats. The echo signals were acquired during a decalcification process by Ethylenediaminetetraacetic Acid (EDTA). The results were compared to Quantitative Computed Tomography (QCT) and inductively coupled plasma optical emission spectrometry measurements for validation. Integrated Reflection Coefficient (IRC) reflection parameters and Frequency Slope of Reflection Transfer Function (FSRTF) during demineralization tended to decrease, while the backscattering parameter Apparent Integrated Backscatter (AIB) increased and Frequency Slope of Apparent Backscatter (FSAB) showed an oscillatory behavior with no defined trend. Results indicate a clear relation between demineralization and the corresponding decrease in the reflection parameters and increase in the scattering parameters. The trend analysis of the fall curve of the chemical elements showed a better relationship between IRC and QCT. It was possible to monitor bone changes after ions losses, through the QUS. Thus, it is an indication that the proposed protocol has potential to characterize bone tissue in animal models, providing consistent results towards standardization of bone characterization studies by QUS endorsing its use in humans.

EXPLORING CORTICAL BONE DENSITY THROUGH THE ULTRASOUND INTEGRATED REFLECTION COEFFICIENT

ABSTRACT Objective: This work evaluates the relationship between ultrasonic reflection and bone density from fourteen cylindrical bovine cortical bone samples (3.0-cm thick). Methods: Twenty US reflection signals per sample were acquired along the bone surface (2.0-mm step). The Integrated Reflection Coefficient (IRC) from each signal was compared to Quantitative Computed Tomography (QCT). Results: Seven IRC and QCT curves presented Pearsons Correlation R-values above 0.5. For weak correlation curves, QCT and IRC showed similar trends in several segments. Conclusion: IRC was sensitive to bone density variation. Level of Evidence: Experimental Study, Investigating a Diagnostic Test.

Evaluating periodicity of trabecular bone phantoms using ultrasound signals

The aim of this work was to characterize the periodicity of a commercial available trabecular bone phantom with ultrasound (US) backscattered signals. Three US frequencies were applied (1.0, 2.25 and 5.0 MHz), and spectral analysis methods were used to estimate the mean scatterer spacing (MSS) of 100 signals/sample from five different samples. The results showed that it is possible to estimate the medium periodicity (trabecular spacings varying from 1.5 to 2.5 mm), and at higher frequencies the average MSS decreased, which is expected because of a higher spatial resolution (identification of the trabecular thickness periodicity). MSS values are in agreement with intertrabecular distances declared by the product supplier.