Ex vivo vibro-acoustography characterization of osteoporosis in an experimental mice model.

BACKGROUND: Osteoporosis is a highly prevalent multifactorial osteometabolic disease, classically diagnosed, in vivo, by dual energy X-ray absorptiometry (DXA). This study evaluated osteoporosis, ex vivo, using vibro-acoustography (VA), an elastographic technique based on ultrasound radiation force. METHODS: Three groups of mice femurs were used: (I) control group (CG), (II) osteoporosis group (OG) and (III) treated osteoporosis group (TOG), in which the animals received pamidronate, an antiresorptive drug. Evaluation was performed in an acoustic tank, using two high frequency focused beams produced by a confocal ultrasonic transducer. A hydrophone registered the low frequency acoustic response (AR) of bone samples. We used micro-computed tomography (microCT) as the reference standard and evaluated the correlation between VA and microCT parameters. RESULTS: The spectral analyses of the ARs with estimated area under the curve (AUC) values (mean; st. dev.) were, respectively, 1.29e-07 and 9.32e-08 for the CG, 3.25e-08 and 2.16e-08 for the OG, and 1.50e-07 and 8.37e-08 for the TOG. VA differentiated the experimental groups (P<0.01) and the results were reproducible [interclass correlation coefficient (ICC): 0.43 (95% CI: 0.15-0.71)]. There was also a statistically significant association between VA and microCT connectivity (Conn.) (r=0.80; P<0.01) and connectivity density (Conn. D) (r=0.76; P<0.01). CONCLUSIONS: These results encourage further studies aimed at evaluating the potential use of VA for the diagnosis of osteoporosis as a relatively low-cost and radiation-free alternative to DXA.

Biomimetic phantom with anatomical accuracy for evaluating brain volumetric measurements with magnetic resonance imaging.

Purpose: Brain image volumetric measurements (BVM) methods have been used to quantify brain tissue volumes using magnetic resonance imaging (MRI) when investigating abnormalities. Although BVM methods are widely used, they need to be evaluated to quantify their reliability. Currently, the gold-standard reference to evaluate a BVM is usually manual labeling measurement. Manual volume labeling is a time-consuming and expensive task, but the confidence level ascribed to this method is not absolute. We describe and evaluate a biomimetic brain phantom as an alternative for the manual validation of BVM. Methods: We printed a three-dimensional (3D) brain mold using an MRI of a three-year-old boy diagnosed with Sturge-Weber syndrome. Then we prepared three different mixtures of styrene-ethylene/butylene-styrene gel and paraffin to mimic white matter (WM), gray matter (GM), and cerebrospinal fluid (CSF). The mold was filled by these three mixtures with known volumes. We scanned the brain phantom using two MRI scanners, 1.5 and 3.0 Tesla. Our suggestion is a new challenging model to evaluate the BVM which includes the measured volumes of the phantom compartments and its MRI. We investigated the performance of an automatic BVM, i.e., the expectation-maximization (EM) method, to estimate its accuracy in BVM. Results: The automatic BVM results using the EM method showed a relative error (regarding the phantom volume) of 0.08, 0.03, and 0.13 ( ± 0.03 uncertainty) percentages of the GM, CSF, and WM volume, respectively, which was in good agreement with the results reported using manual segmentation. Conclusions: The phantom can be a potential quantifier for a wide range of segmentation methods.

Nondestructive inspection of metal specimen using tone-burst vibro-acoustography.

Even though the pulse-echo ultrasonic technique is commonly used for the assessment of metal structures, it has some inherent limitations. Vibro-acoustography (VA) is a relatively new ultrasonic technique which has demonstrated a great potential in revealing defects in objects, however it is traditionally used to analyze the integrity of specimens made of low-stiffness materials. This work presents the evaluation of the performance of VA technique for the inspection of a steel structure, which was manufactured with defects of known geometry on its inner surface. All the inspection process was done automatically, from the data acquisition to the image processing for characterizing the defects. Experimental results show that VA was able to identify and characterize even the smallest defects in the structure, with a diameter of 2 mm. In addition, the results show that VA was able to characterize the artificial defects in the steel structure with almost the same errors as the traditional pulse-echo method, which indicates a potential use of VA in the inspection of materials with high mechanical stiffness.

Photoacoustic-based thermal image formation and optimization using an evolutionary genetic algorithm

Abstract Introduction For improved efficiency and security in heat application during hyperthermia, it is important to monitor tissue temperature during treatments. Photoacoustic (PA) pressure wave amplitude has a temperature dependence given by the Gruenesein parameter. Consequently, changes in PA signal amplitude carry information about temperature variation in tissue. Therefore, PA has been proposed as an imaging technique to monitor temperature during hyperthermia. However, no studies have compared the performance of different algorithms to generate PA-based thermal images. Methods Here, four methods to estimate variations in PA signal amplitude for thermal image formation were investigated: peak-to-peak, integral of the modulus, autocorrelation of the maximum value, and energy of the signal. Changes in PA signal amplitude were evaluated using a 1-D window moving across the entire image. PA images were acquired for temperatures ranging from 36oC to 41oC using a phantom immersed in a temperature controlled thermal bath. Results The results demonstrated that imaging processing parameters and methods involved in tracking variations in PA signal amplitude drastically affected the sensitivity and accuracy of thermal images formation. The sensitivity fluctuated more than 20% across the different methods and parameters used. After optimizing the parameters to generate the thermal images using an evolutionary genetic algorithm (GA), the percentage of pixels within the acceptable error was improved, in average, by 7.5%. Conclusion Optimization of processing parameters using GA could increase the accuracy of measurement for this experimental setup and improve quality of PA-based thermal images.

Patient-specific neurosurgical phantom: assessment of visual quality, accuracy, and scaling effects.

BACKGROUND: Training in medical education depends on the availability of standardized materials that can reliably mimic the human anatomy and physiology. One alternative to using cadavers or animal bodies is to employ phantoms or mimicking devices. Styrene-ethylene/butylene-styrene (SEBS) gels are biologically inert and present tunable properties, including mechanical properties that resemble the soft tissue. Therefore, SEBS is an alternative to develop a patient-specific phantom, that provides real visual and morphological experience during simulation-based neurosurgical training. RESULTS: A 3D model was reconstructed and printed based on patient-specific magnetic resonance images. The fused deposition of polyactic acid (PLA) filament and selective laser sintering of polyamid were used for 3D printing. Silicone and SEBS materials were employed to mimic soft tissues. A neuronavigation protocol was performed on the 3D-printed models scaled to three different sizes, 100%, 50%, and 25% of the original dimensions. A neurosurgery team (17 individuals) evaluated the phantom realism as "very good" and "perfect" in 49% and 31% of the cases, respectively, and rated phantom utility as "very good" and "perfect" in 61% and 32% of the cases, respectively. Models in original size (100%) and scaled to 50% provided a quantitative and realistic visual analysis of the patient's cortical anatomy without distortion. However, reduction to one quarter of the original size (25%) hindered visualization of surface details and identification of anatomical landmarks. CONCLUSIONS: A patient-specific phantom was developed with anatomically and spatially accurate shapes, that can be used as an alternative for surgical planning. Printed models scaled to sizes that avoided quality loss might save time and reduce medical training costs.

Preliminary results of vibro-acoustography evaluation of bone surface and bone fracture.

BACKGROUND: Vibro-acoustography (VA) uses two co-focused ultrasound beams with slightly different frequencies. The beams interact and generate a low-frequency focus to excite an object. METHODS: A two-element confocal ultrasound transducer with central frequency at 3.2 MHz was used to generate the low-frequency excitation (30 kHz) and the response of the bone to that excitation was acquired by a dedicated hydrophone. The face of the confocal transducer was positioned parallel to the surface of the bone at a focal length of 7 cm. The hydrophone was fixed to the side of the transducer, out of the path of the ultrasonic beam. RESULTS: The resulting image clearly showed the bone fracture with resolution of 0.25 mm and high contrast with well-defined borders. CONCLUSIONS: In this paper, we present preliminary results of VA imaging of bone surface and of bone fracture using an experimental set-up. Our results encourage future studies using VA to evaluate bone fractures.

Reproducibility of abdominal fat assessment by ultrasound and computed tomography.

OBJECTIVE: To test the accuracy and reproducibility of ultrasound and computed tomography (CT) for the quantification of abdominal fat in correlation with the anthropometric, clinical, and biochemical assessments. MATERIALS AND METHODS: Using ultrasound and CT, we determined the thickness of subcutaneous and intra-abdominal fat in 101 subjects-of whom 39 (38.6%) were men and 62 (61.4%) were women-with a mean age of 66.3 years (60-80 years). The ultrasound data were correlated with the anthropometric, clinical, and biochemical parameters, as well as with the areas measured by abdominal CT. RESULTS: Intra-abdominal thickness was the variable for which the correlation with the areas of abdominal fat was strongest (i.e., the correlation coefficient was highest). We also tested the reproducibility of ultrasound and CT for the assessment of abdominal fat and found that CT measurements of abdominal fat showed greater reproducibility, having higher intraobserver and interobserver reliability than had the ultrasound measurements. There was a significant correlation between ultrasound and CT, with a correlation coefficient of 0.71. CONCLUSION: In the assessment of abdominal fat, the intraobserver and interobserver reliability were greater for CT than for ultrasound, although both methods showed high accuracy and good reproducibility.

OBJETIVO: Testar a precisão e a reprodutibilidade da ultrassonografia (US) e da tomografia computadorizada (TC) para a quantificação da gordura abdominal, em correlação com as avaliações antropométricas e clinicolaboratoriais. MATERIAIS E MÉTODOS: Foram determinadas, por meio da US e da TC, as espessuras subcutâneas e intra-abdominais em 101 indivíduos, sendo 39 homens (38,6%) e 62 mulheres (61,4%), com idade média de 66,3 anos (60-80 anos). Os dados obtidos pela US foram correlacionados com os parâmetros antropométricos, clinicolaboratoriais e com as áreas abdominais medidas pela TC. RESULTADOS: A espessura da gordura intra-abdominal foi a variável que obteve maior coeficiente de correlação com as áreas adiposas abdominais. A TC mostrou maior reprodutibilidade nas mensurações da gordura abdominal, apresentando maior taxa de concordância intraexaminador e interexaminador em comparação com a US. Observou-se índice de correlação de 71% entre a US e a TC. CONCLUSÃO: Houve maior concordância intraexaminador e interexaminador na avaliação da gordura abdominal por TC, comparativamente à US, porém ambos os métodos mostraram alta precisão e boa reprodutibilidade.

Reproducibility of abdominal fat assessment by ultrasound and computed tomography / Reprodutibilidade da avaliação da gordura abdominal pela ultrassonografia e tomografia computadorizada

Abstract Objective: To test the accuracy and reproducibility of ultrasound and computed tomography (CT) for the quantification of abdominal fat in correlation with the anthropometric, clinical, and biochemical assessments. Materials and Methods: Using ultrasound and CT, we determined the thickness of subcutaneous and intra-abdominal fat in 101 subjects-of whom 39 (38.6%) were men and 62 (61.4%) were women-with a mean age of 66.3 years (60-80 years). The ultrasound data were correlated with the anthropometric, clinical, and biochemical parameters, as well as with the areas measured by abdominal CT. Results: Intra-abdominal thickness was the variable for which the correlation with the areas of abdominal fat was strongest (i.e., the correlation coefficient was highest). We also tested the reproducibility of ultrasound and CT for the assessment of abdominal fat and found that CT measurements of abdominal fat showed greater reproducibility, having higher intraobserver and interobserver reliability than had the ultrasound measurements. There was a significant correlation between ultrasound and CT, with a correlation coefficient of 0.71. Conclusion: In the assessment of abdominal fat, the intraobserver and interobserver reliability were greater for CT than for ultrasound, although both methods showed high accuracy and good reproducibility.

Resumo Objetivo: Testar a precisão e a reprodutibilidade da ultrassonografia (US) e da tomografia computadorizada (TC) para a quantificação da gordura abdominal, em correlação com as avaliações antropométricas e clinicolaboratoriais. Materiais e Métodos: Foram determinadas, por meio da US e da TC, as espessuras subcutâneas e intra-abdominais em 101 indivíduos, sendo 39 homens (38,6%) e 62 mulheres (61,4%), com idade média de 66,3 anos (60-80 anos). Os dados obtidos pela US foram correlacionados com os parâmetros antropométricos, clinicolaboratoriais e com as áreas abdominais medidas pela TC. Resultados: A espessura da gordura intra-abdominal foi a variável que obteve maior coeficiente de correlação com as áreas adiposas abdominais. A TC mostrou maior reprodutibilidade nas mensurações da gordura abdominal, apresentando maior taxa de concordância intraexaminador e interexaminador em comparação com a US. Observou-se índice de correlação de 71% entre a US e a TC. Conclusão: Houve maior concordância intraexaminador e interexaminador na avaliação da gordura abdominal por TC, comparativamente à US, porém ambos os métodos mostraram alta precisão e boa reprodutibilidade.

A magneto-motive ultrasound platform designed for pre-clinical and clinical applications

Abstract Introduction Magneto-motive ultrasound (MMUS) combines magnetism and ultrasound (US) to detect magnetic nanoparticles in soft tissues. One type of MMUS called shear-wave dispersion magneto-motive ultrasound (SDMMUS) analyzes magnetically induced shear waves (SW) to quantify the elasticity and viscosity of the medium. The lack of an established presets or protocols for pre-clinical and clinical studies currently limits the use of MMUS techniques in the clinical setting. Methods This paper proposes a platform to acquire, process, and analyze MMUS and SDMMUS data integrated with a clinical ultrasound equipment. For this purpose, we developed an easy-to-use graphical user interface, written in C++/Qt4, to create an MMUS pulse sequence and collect the ultrasonic data. We designed a graphic interface written in MATLAB to process, display, and analyze the MMUS images. To exemplify how useful the platform is, we conducted two experiments, namely (i) MMUS imaging to detect magnetic particles in the stomach of a rat, and (ii) SDMMUS to estimate the viscoelasticity of a tissue-mimicking phantom containing a spherical target of ferrite. Results The developed software proved to be an easy-to-use platform to automate the acquisition of MMUS/SDMMUS data and image processing. In an in vivo experiment, the MMUS technique detected an area of 6.32 ± 1.32 mm2 where magnetic particles were heterogeneously distributed in the stomach of the rat. The SDMMUS method gave elasticity and viscosity values of 5.05 ± 0.18 kPa and 2.01 ± 0.09 Pa.s, respectively, for a tissue-mimicking phantom. Conclusion Implementation of an MMUS platform with addressed presets and protocols provides a step toward the clinical implementation of MMUS imaging equipment. This platform may help to localize magnetic particles and quantify the elasticity and viscosity of soft tissues, paving a way for its use in pre-clinical and clinical studies.

Evaluation of postural balance in mild cognitive impairment through a three-dimensional electromagnetic system / Avaliação do equilíbrio corporal no comprometimento cognitivo leve através de sistema eletromagnético tridimensional

ABSTRACT INTRODUCTION: Elderly people with cognitive impairment are at greater risk for falls; thus, an understanding of the earliest stages of cognitive decline is necessary. OBJECTIVE: To compare postural balance between elderly people with and without mild cognitive impairment using a three-dimensional system. METHODS: Thirty elderly people with mild cognitive impairment and thirty healthy elderly subjects were selected. Static posturography was performed using three-dimensional electromagnetic equipment and the following parameters were evaluated: maximum displacement, mean speed and total trajectory. Open- and closed-eye stabilometric variable comparisons between groups and within each group were carried out, and a relationship between the Mini Mental State Examination and the total trajectory of all elderly subjects was determined. RESULTS: The analysis among open- and closed-eye conditions showed a significant difference in maximum anteroposterior displacement in the control group and a significant difference in all stabilometric variables in the mild cognitive impairment group. A significant difference between the groups in all variables in the closed-eye condition was observed. There was a strong correlation between cognitive performance and total trajectory. CONCLUSION: Evaluations showed decrease in balance in elderly people with mild cognitive impairment. Presence of anteroposterior displacement can be an early sign of postural control impairment, and the evaluation with visual restriction can be useful in detecting small postural instabilities.

Resumo Introdução: Idosos com alteração cognitiva apresentam maior risco de quedas; assim, é importante compreender as primeiras fases do declínio cognitivo. Objetivo: Comparar o equilíbrio corporal entre idosos com e sem comprometimento cognitivo leve através de um sistema tridimensional. Método: Trinta idosos com comprometimento cognitivo leve e 30 idosos saudáveis foram selecionados. A posturografia estática foi realizada utilizando equipamento eletromagnético tridimensional, e foram avaliados os parâmetros deslocamento máximo, velocidade média e trajetória total. Foi realizada comparação das variáveis estabilométricas com olho aberto e olho fechado intragrupo e intergrupos, e foi estabelecida a relação entre o Mini Exame do Estado Mental e a trajetória total de todos os idosos. Resultados: A análise entre olho aberto e olho fechado no grupo de controle evidenciou uma diferença significativa no deslocamento anteroposterior máximo; no grupo com comprometimento cognitivo leve, houve diferença significativa em todas as variáveis estabilométricas. Foi observada diferença significativa entre os grupos em todas as variáveis na condição de olho fechado. Houve forte correlação entre desempenho cognitivo e trajetória total. Conclusão: As avaliações evidenciaram diminuição do equilíbrio nos idosos com comprometimento cognitivo leve. O deslocamento anteroposterior pode ser um sinal precoce de comprometimento do controle postural, e a avaliação com restrição visual pode ser útil na detecção de pequenas instabilidades posturais.

Evaluation of postural balance in mild cognitive impairment through a three-dimensional electromagnetic system.

INTRODUCTION: Elderly people with cognitive impairment are at greater risk for falls; thus, an understanding of the earliest stages of cognitive decline is necessary. OBJECTIVE: To compare postural balance between elderly people with and without mild cognitive impairment using a three-dimensional system. METHODS: Thirty elderly people with mild cognitive impairment and thirty healthy elderly subjects were selected. Static posturography was performed using three-dimensional electromagnetic equipment and the following parameters were evaluated: maximum displacement, mean speed and total trajectory. Open- and closed-eye stabilometric variable comparisons between groups and within each group were carried out, and a relationship between the Mini Mental State Examination and the total trajectory of all elderly subjects was determined. RESULTS: The analysis among open- and closed-eye conditions showed a significant difference in maximum anteroposterior displacement in the control group and a significant difference in all stabilometric variables in the mild cognitive impairment group. A significant difference between the groups in all variables in the closed-eye condition was observed. There was a strong correlation between cognitive performance and total trajectory. CONCLUSION: Evaluations showed decrease in balance in elderly people with mild cognitive impairment. Presence of anteroposterior displacement can be an early sign of postural control impairment, and the evaluation with visual restriction can be useful in detecting small postural instabilities.

A computational tool as support in B-mode ultrasound diagnostic quality control

INTRODUCTION: The quality control (QC) of biomedical equipment is a very important process for the quality assurance of the instruments used in diagnoses and treatments. Ultrasound diagnostic imaging is one of the most widely used techniques for diagnostic imaging in hospitals and medical clinics. However, the time required to complete several B-mode imaging QC tests in ultrasound equipment is very critical for a hospital with a high number of exams. Here, we present a computational tool to assist in the acquisition and storage of data from multiple QC tests in B-mode ultrasound diagnostic equipment to promote an efficient alternative for QC in clinical routines. METHODS: The project was planned and implemented in C++ programming language and compiled for two computing platforms: Windows and Linux. The most common QC routine tests for B-mode ultrasound were combined in a simple graphical user interface. RESULTS: After entering all of the correct QC information in the graphical user interface, a final report in PDF format was created. CONCLUSION: The proposed program has been helpful for students and diagnostic professionals and is a quick and easy application for several QC tests for B-mode ultrasound diagnostic equipment. Our program seeks to help in the dissemination and application of QC tests for B-mode ultrasound equipment in hospitals and clinics and for the technical training of ultrasound professionals.

A pilot study on the evaluation of postural strategies in young and elderly subjects using a tridimensional electromagnetic system.

UNLABELLED: One resorts to various postural strategies while attempting to maintain balance. OBJECTIVE: To assess the postural strategies adopted by young and elderly subjects in varying sensory conditions by using a system of tridimensional electromagnetic sensors positioned on the projection of the first thoracic vertebra and on the sacral region. Postural oscillation values for young and elderly subjects were also reported. METHOD: This observational cross-sectional study enrolled 25 young and 16 elderly individuals. A Polhemus™ device equipped with two sensors was used to assess postural oscillation parameters (maximum displacement, mean velocity, and trajectory). Data acquisition was carried out with subjects standing while undergoing a 90-second test in four sensory conditions: eyes opened, eyes closed, on a stable surface, and on an unstable surface. RESULTS: Sensors 1 and 2 presented significant cross-correlations in all sensory conditions for both groups (r > 0.99; p < 0.001). No statistically significant differences were seen when the cross-correlations for both groups were compared. CONCLUSION: This study presented an important tool to analyze postural oscillation and assess the postural strategies of young and elderly subjects in different sensory conditions. Young and elderly individuals presented strong correlations between sensors (ankle strategy), but no statistically significant differences were seen between groups.

Um estudo piloto na avaliação das estratégias posturais em jovens e idosos usando um sistema eletromagnético tridimensional / A pilot study on the evaluation of postural strategies in young and elderly subjects using a tridimensional electromagnetic system

Para manter o equilíbrio postural, algumas estratégias posturais são normalmente usadas. OBJETIVO: Avaliar as estratégias posturais de jovens e idosos em diferentes condições sensoriais usando um sistema de sensores eletromagnéticos tridimensionais posicionados na primeira vértebra torácica e região sacral. Também reportamos valores de oscilação postural dos jovens e idosos. MÉTODO: Estudo transversal observacional. Participaram do estudo 25 jovens e 16 idosas. O equipamento PolhemusTM com dois sensores foi usado para avaliar os parâmetros de oscilação postural (deslocamento máximo, velocidade média e trajetória). A aquisição dos dados foi realizada com os sujeitos em pé, realizando um teste de 90 segundos para as quatro condições sensoriais: olhos abertos e fechados nas superfícies estável e instável. RESULTADOS: Os sensores 1 e 2 apresentaram alta correlação cruzada em todas as condições sensoriais para ambos os grupos (r > 0.99; p < 0.001). Comparando a correlação cruzada entre os grupos, não foram observadas diferenças significativas. CONCLUSÃO: Este estudo apresentou uma importante ferramenta na análise de oscilação postural e na avaliação das estratégias posturais de jovens e idosos em diferentes condições sensoriais. Os jovens e idosos apresentaram uma forte correlação entre os sensores (estratégia do tornozelo), porém, não foram observadas diferenças significativas entre os grupos.

One resorts to various postural strategies while attempting to maintain balance. OBJECTIVE: To assess the postural strategies adopted by young and elderly subjects in varying sensory conditions by using a system of tridimensional electromagnetic sensors positioned on the projection of the first thoracic vertebra and on the sacral region. Postural oscillation values for young and elderly subjects were also reported. METHOD: This observational cross-sectional study enrolled 25 young and 16 elderly individuals. A PolhemusTM device equipped with two sensors was used to assess postural oscillation parameters (maximum displacement, mean velocity, and trajectory). Data acquisition was carried out with subjects standing while undergoing a 90-second test in four sensory conditions: eyes opened, eyes closed, on a stable surface, and on an unstable surface. RESULTS: Sensors 1 and 2 presented significant cross-correlations in all sensory conditions for both groups (r > 0.99; p < 0.001). No statistically significant differences were seen when the cross-correlations for both groups were compared. CONCLUSION: This study presented an important tool to analyze postural oscillation and assess the postural strategies of young and elderly subjects in different sensory conditions. Young and elderly individuals presented strong correlations between sensors (ankle strategy), but no statistically significant differences were seen between groups.

A hybrid transducer to magnetically and ultrasonically evaluate magnetic fluids.

Ultrasound, magnetic fields, and optical techniques have been explored for clinical diagnosis and therapy. However, these techniques have limitations. In this study, we constructed and characterized a transducer to magnetically and ultrasonically investigate samples labeled with magnetic particles. The transducer is a hybrid system consisting of an ac biosusceptometer (ACB) and an ultrasonic transducer. The basic operation principle consisted of measuring the magnetization and microvibrations of ferromagnetic particles (37 and 70 µm) mixed in yogurt and excited by an external alternating magnetic field generated by the ACB's excitation coils. The vibration of the ferromagnetic particles was measured in phantoms using a Doppler ultrasonic transducer; we verified the sensitivity to detecting the vibrations at low concentrations of ferromagnetic material (~1%). The responses of the susceptometer and Doppler ultrasound linearly depended on the voltage level applied to the magnetizing coils at low ferromagnetic particle concentrations (⩽ 5%). We also conducted a repeatability test on the prototype, which indicated a deviation of 0.94% and 0.25% in the Doppler and susceptometric measurements, respectively. We can conclude that the hybrid transducer technique has potential clinical applications.

A new method to analyze the subjective visual vertical in patients with bilateral vestibular dysfunction.

OBJECTIVE: The aim of this study was to assess the subjective visual vertical in patients with bilateral vestibular dysfunction and to propose a new method to analyze subjective visual vertical data in these patients. METHODS: Static subjective visual vertical tests were performed in 40 subjects split into two groups. Group A consisted of 20 healthy volunteers, and Group B consisted of 20 patients with bilateral vestibular dysfunction. Each patient performed six measurements of the subjective visual vertical test, and the mean values were calculated and analyzed. RESULTS: Analyses of the numerical values of subjective visual vertical deviations (the conventional method of analysis) showed that the mean deviation was 0.326±1.13º in Group A and 0.301±1.87º in Group B. However, by analyzing the absolute values of the subjective visual vertical (the new method of analysis proposed), the mean deviation became 1.35±0.48º in Group A and 2.152±0.93º in Group B. The difference in subjective visual vertical deviations between groups was statistically significant (p<0.05) only when the absolute values and the range of deviations were considered. CONCLUSION: An analysis of the absolute values of the subjective visual vertical more accurately reflected the visual vertical misperception in patients with bilateral vestibular dysfunction.

A newmethod to analyze the subjective visual vertical in patients with bilateral vestibular dysfunction

OBJECTIVE: The aim of this study was to assess the subjective visual vertical in patients with bilateral vestibular dysfunction and to propose a new method to analyze subjective visual vertical data in these patients. METHODS: Static subjective visual vertical tests were performed in 40 subjects split into two groups. Group A consisted of 20 healthy volunteers, and Group B consisted of 20 patients with bilateral vestibular dysfunction. Each patient performed six measurements of the subjective visual vertical test, and the mean values were calculated and analyzed. RESULTS: Analyses of the numerical values of subjective visual vertical deviations (the conventional method of analysis) showed that the mean deviation was 0.326±1.13º in Group A and 0.301±1.87º in Group B. However, by analyzing the absolute values of the subjective visual vertical (the new method of analysis proposed), the mean deviation became 1.35±0.48º in Group A and 2.152±0.93º in Group B. The difference in subjective visual vertical deviations between groups was statistically significant (p,<0.05) only when the absolute values and the range of deviations were considered. CONCLUSION: An analysis of the absolute values of the subjective visual vertical more accurately reflected the visual vertical misperception in patients with bilateral vestibular dysfunction.

Influência da obesidade e da força de preensão palmar no equilíbrio postural estático de idosas ativas / Influence of obesity and handgrip strength in the static postural balance of active older women

O objetivo deste estudo foi investigar a influência da obesidade e da força de preensão palmar (FPP) no equilíbrio postural estático de idosas ativas nas condições de olhos abertos e fechados. Participaram 31 idosas (16 eutróficas e 15 obesas). A idade média e o Índice de Massa Corpórea (IMC) das eutróficas foram, respectivamente, 68,3±2,7 anos e 23,4±1,6kg/m², e das obesas 69,1±2,7 anos e 33,5±3kg/m². A FPP foi avaliada usando um dinamômetro (JAMAR). O equilíbrio postural estático foi avaliado usando um sistema tridimensional nas condições de olhos abertos (OA) e fechados (OF), durante 90 segundos cada condição. A FPP das idosas eutróficas foi 25,1±4,6kgf e das obesas foi 24,8±5,2kgf, não havendo diferenças significativas. No equilíbrio postural, foram observadas diferenças significativas entre os grupos apenas no deslocamento máximo a-p com AO (p=0,04) e OF (p<0,01), com as idosas obesas apresentando menor deslocamento a-p em relação às eutróficas. Não houve correlação entre o deslocamento máximo a-p com IMC e a FPP. No presente estudo FPP não influenciou o equilíbrio postural estático, enquanto a obesidade foi fator determinante de menor deslocamento ântero-posterior de idosas ativas.

The objective of this study was to investigate the influence of the obesity and handgrip strength on the static balance of active older women in the opened and closed eyes conditions. Thirty one women aged from 65 to 75 years (16 eutrophic and 15 obese) were evaluated. Mean age and BMI of the eutrophic women were, respectively, 68.3±2.7 years and 23.4±1.6kg/m², and of the obese women were 69.1±2.7 years and 33.5±3kg/m². Handgrip strength was evaluated using a dynamometer (JAMAR). A tridimensional sensors system was used to evaluate the static postural balance. The tests were performed for 90 seconds, with eyes opened and closed. The mean handgrip strength of the eutrophic women was 25.1±4.6kgf and of the obese women was 24.8±5.2kgf, (p>0,05). Significant differences between groups were only observed in the maximum displacement with opened eyes (p=0,04) and closed eyes(p<0,01). There was no correlation between the maximum displacement neither with the BMI or the handgrip strength. The present study showed smaller a-p displacement in obese than in eutrophic women, with major statistic difference in the eyes closed condition. In the present study, the handgrip strength did not influence the static balance, however the obesity was a determinant factor for the smaller a-p displacement of the active older women.

Analysis of static postural balance using a 3d electromagnetic system.

UNLABELLED: Early detection of postural disorders is essential for timely interventions in patients with imbalance. AIM: A pilot study describing a new tool for evaluating static postural balance. STUDY DESIGN: A cross-sectional study of a contemporary series. MATERIAL AND METHOD: Twenty-five volunteers (15 women and 10 men) were evaluated. The mean age was 25.8 ± 4.2 years, the mean weight was 63.9 ± 13.1Kg, the mean height was 1.68 ± 0.08 m and the body mass index was 22.3±3.3kg/m2. Posturography was done by analysing postural sway with an electromagnetic system; a sensor was attached to the skin over the spinous process of the first thoracic vertebra. Tests were carried out with the subjects in the orthostatic position for 90 seconds, with eyes opened(EO) and closed(EC) on stable and unstable surfaces. RESULTS: When the influence of the surface was analyzed (stable x unstable) in the EO condition, there were significant differences in the middle-lateral parameters (m-l) (p=0.004) and total path (p=0.01), and in the m-l (p=0.004) and total (p=0.014) speed. In the EC condition, there were significant differences in all parameters (p<0.001). The influence of the vision was observed in all parameters only on unstable surfaces (p<0.05). CONCLUSION: The new tool was efficient for analysing postural sway.

Análise do equilíbrio postural estático utilizando um sistema eletromagnético tridimensional / Analysis of static postural balance using a 3d electromagnetic system

A detecção precoce de distúrbios posturais é fundamental para a promoção de intervenções adequadas para pacientes com desequilíbrios. OBJETIVO: Este é um estudo piloto que descreve uma nova ferramenta para avaliação do equilíbrio postural estático. FORMA DE ESTUDO: Coorte contemporânea com corte transversal. MATERIAL E MÉTODO: Foram avaliados 25 voluntários (15 mulheres e 10 homens). Idade média de 25,8±4,2anos, peso 63,9±13,1Kg, estatura 1,68±0,08m e índice de massa corporal 22,3±3,3kg/m2. A posturografia foi realizada por meio da análise de oscilação postural utilizando um equipamento eletromagnético com um sensor fixado sobre o processo espinhoso da 1ª vértebra torácica. Os testes foram realizados com os sujeitos na posição ortostática durante 90 segundos, para as condições de olhos abertos (OA) e fechados (OF) em superfície estável e instável. RESULTADOS: Quando analisada a influência da superfície (estável x instável) para o equilíbrio postural na condição OA, foram observadas diferenças significativas nos parâmetros de trajetória médio-lateral (m-l) (p=0.004) e total (p=0.014) e de velocidade m-l (p=0.004) e total (p=0.014). Na condição OF, foram observadas diferenças significativas em todos os parâmetros estudados (p<0.001). Houve influência da visão em todos os parâmetros apenas na superfície instável (p<0.05). CONCLUSÃO: A ferramenta utilizada se mostrou eficaz para a análise da oscilação postural.

Early detection of postural disorders is essential for timely interventions in patients with imbalance. AIM: A pilot study describing a new tool for evaluating static postural balance. STUDY DESIGN: A cross-sectional study of a contemporary series. MATERIAL AND METHOD: Twenty-five volunteers (15 women and 10 men) were evaluated. The mean age was 25.8 ± 4.2 years, the mean weight was 63.9 ± 13.1Kg, the mean height was 1.68 ± 0.08 m and the body mass index was 22.3±3.3kg/m2. Posturography was done by analysing postural sway with an electromagnetic system; a sensor was attached to the skin over the spinous process of the first thoracic vertebra. Tests were carried out with the subjects in the orthostatic position for 90 seconds, with eyes opened(EO) and closed(EC) on stable and unstable surfaces. RESULTS: When the influence of the surface was analyzed (stable x unstable) in the EO condition, there were significant differences in the middle-lateral parameters (m-l) (p=0.004) and total path (p=0.01), and in the m-l (p=0.004) and total (p=0.014) speed. In the EC condition, there were significant differences in all parameters (p<0.001). The influence of the vision was observed in all parameters only on unstable surfaces (p<0.05). CONCLUSION: The new tool was efficient for analysing postural sway.