In Vivo Endoluminal Ultrasound Biomicroscopy and Endoscopy of Inflamed Rat Esophagus.

The development of high-frequency endoscopic ultrasound for the investigation of models of esophageal disease may offer insights for future translation to human imaging. With respect to small animal models of esophageal diseases, ultrasound imaging instrumentation must employ frequencies scaled up to maintain the compromise between image resolution and inspected region. In this sense, a 40-MHz endoluminal ultrasound biomicroscopy (eUBM) system and an endoscope were tested as diagnostic methods of imaging rat esophageal lesions in the acute and chronic phases caused by sodium hydroxide. Although endoscopy allowed grading of the esophagus in accordance with a classification specific to the epithelial alterations and including hyperemia, edema, exudates, fibrin and superficial and deep ulcerations, the eUBM images yielded the detection of superficial and deep ulcerations, as well as wall alterations caused by edema and inflammatory infiltrate in the submucosa. Additionally, eUBM enabled wall thickness measurements, which were statistically significantly increased (p < 0.05) in the acute phase.

GRN and MAPT Mutations in 2 Frontotemporal Dementia Research Centers in Brazil.

BACKGROUND: Mutations in GRN (progranulin) and MAPT (microtubule-associated protein tau) are among the most frequent causes of monogenic frontotemporal dementia (FTD), but data on the frequency of these mutations in regions such as Latin America are still lacking. OBJECTIVE: We aimed to investigate the frequencies of GRN and MAPT mutations in FTD cohorts from 2 Brazilian dementia research centers, the University of Sao Paulo and the Federal University of Minas Gerais medical schools. METHODS: We included 76 probands diagnosed with behavioral-variant FTD (n=55), semantic-variant Primary Progressive Aphasia (PPA) (n=11), or nonfluent-variant PPA (n=10). Twenty-five percent of the cohort had at least 1 relative affected with FTD. RESULTS: Mutations in GRN were identified in 7 probands, and in MAPT, in 2 probands. We identified 3 novel GRN mutations (p.Q130X, p.317Afs*12, and p.K259Afs*23) in patients diagnosed with nonfluent-variant PPA or behavioral-variant FTD. Plasma progranulin levels were measured and a cutoff value of 70 ng/mL was found, with 100% sensitivity and specificity to detect null GRN mutations. CONCLUSIONS: The frequency of GRN mutations was 9.6% and that of MAPT mutations was 7.1%. Among familial cases of FTD, the frequency of GRN mutations was 31.5% and that of MAPT mutations was 10.5%.

Simultaneous follow-up of mouse colon lesions by colonoscopy and endoluminal ultrasound biomicroscopy.

AIM: To evaluate the potential use of colonoscopy and endoluminal ultrasonic biomicroscopy (eUBM) to track the progression of mouse colonic lesions. METHODS: Ten mice were treated with a single azoxymethane intraperitoneal injection (week 1) followed by seven days of a dextran sulfate sodium treatment in their drinking water (week 2) to induce inflammation-associated colon tumors. eUBM was performed simultaneously with colonoscopy at weeks 13, 17-20 and 21. A 3.6-F diameter 40 MHz mini-probe catheter was used for eUBM imaging. The ultrasound mini-probe catheter was inserted into the accessory channel of a pediatric flexible bronchofiberscope, allowing simultaneous acquisition of colonoscopic and eUBM images. During image acquisition, the mice were anesthetized with isoflurane and kept in a supine position over a stainless steel heated surgical waterbed at 37 °C. Both eUBM and colonoscopic images were captured and stored when a lesion was detected by colonoscopy or when the eUBM image revealed a modified colon wall anatomy. During the procedure, the colon was irrigated with water that was injected through a flush port on the mini-probe catheter and that acted as the ultrasound coupling medium between the transducer and the colon wall. Once the acquisition of the last eUBM/colonoscopy section for each animal was completed, the colons were fixed, paraffin-embedded, and stained with hematoxylin and eosin. Colon images acquired at the first time-point for each mouse were compared with subsequent eUBM/colonoscopic images of the same sites obtained in the following acquisitions to evaluate lesion progression. RESULTS: All 10 mice had eUBM and colonoscopic images acquired at week 13 (the first time-point). Two animals died immediately after the first imaging acquisition and, consequently, only 8 mice were subjected to the second eUBM/colonoscopy imaging acquisition (at the second time-point). Due to the advanced stage of colonic tumorigenesis, 5 animals died after the second time-point image acquisition, and thus, only three were subjected to the third eUBM/colonoscopy imaging acquisition (the third time-point). eUBM was able to detect the four layers in healthy segments of colon: the mucosa (the first hyperechoic layer moving away from the mini-probe axis), followed by the muscularis mucosae (hypoechoic), the submucosa (the second hyperechoic layer) and the muscularis externa (the second hypoechoic layer). Hypoechoic regions between the mucosa and the muscularis externa layers represented lymphoid infiltrates, as confirmed by the corresponding histological images. Pedunculated tumors were represented by hyperechoic masses in the mucosa layer. Among the lesions that decreased in size between the first and third time-points, one of the lesions changed from a mucosal hyperplasia with ulceration at the top to a mucosal hyperplasia with lymphoid infiltrate and, finally, to small signs of mucosal hyperplasia and lymphoid infiltrate. In this case, while lesion regression and modification were observable in the eUBM images, colonoscopy was only able to detect the lesion at the first and second time-points, without the capacity to demonstrate the presence of lymphoid infiltrate. Regarding the lesions that increased in size, one of them started as a small elevation in the mucosa layer and progressed to a pedunculated tumor. In this case, while eUBM imaging revealed the lesion at the first time-point, colonoscopy was only able to detect it at the second time-point. All colonic lesions (tumors, lymphoid infiltrate and mucosal thickening) were identified by eUBM, while colonoscopy identified just 76% of them. Colonoscopy identified all of the colonic tumors but failed to diagnose lymphoid infiltrates and increased mucosal thickness and failed to differentiate lymphoid infiltrates from small adenomas. During the observation period, most of the lesions (approximately 67%) increased in size, approximately 14% remained unchanged, and 19% regressed. CONCLUSION: Combining eUBM with colonoscopy improves the diagnosis and the follow-up of mouse colonic lesions, adding transmural assessment of the bowel wall.

In vivo endoluminal ultrasound biomicroscopic imaging in a mouse model of colorectal cancer.

RATIONALE AND OBJECTIVES: The gold-standard tool for colorectal cancer detection is colonoscopy, but it provides only mucosal surface visualization. Ultrasound biomicroscopy allows a clear delineation of the epithelium and adjacent colonic layers. The aim of this study was to design a system to generate endoluminal ultrasound biomicroscopic images of the mouse colon, in vivo, in an animal model of inflammation-associated colon cancer. MATERIALS AND METHODS: Thirteen mice (Mus musculus) were used. A 40-MHz miniprobe catheter was inserted into the accessory channel of a pediatric flexible bronchofiberscope. Control mice (n = 3) and mice treated with azoxymethane and dextran sulfate sodium (n = 10) were subjected to simultaneous endoluminal ultrasound biomicroscopy and white-light colonoscopy. The diagnosis obtained with endoluminal ultrasound biomicroscopy and colonoscopy was compared and confirmed by postmortem histopathology. RESULTS: Endoluminal ultrasound biomicroscopic images showed all layers of the normal colon and revealed lesions such as lymphoid hyperplasias and colon tumors. Additionally, endoluminal ultrasound biomicroscopy was able to detect two cases of mucosa layer thickening, confirmed by histology. Compared to histologic results, the sensitivities of endoluminal ultrasound biomicroscopy and colonoscopy were 0.95 and 0.83, respectively, and both methods achieved specificities of 1.0. CONCLUSIONS: Endoluminal ultrasound biomicroscopy can be used, in addition to colonoscopy, as a diagnostic method for colonic lesions. Moreover, experimental endoluminal ultrasound biomicroscopy in mouse models is feasible and might be used to further develop research on the differentiation between benign and malignant colonic diseases.

Features of in vitro ultrasound biomicroscopic imaging and colonoscopy for detection of colon tumor in mice.

The present work tested the capability of ultrasound biomicroscopy (UBM), at 45 MHz, to provide cross-sectional images with appropriate resolution and contrast to detect tumors and determine their penetration depths on the colon of mice, Mus musculus (Linnaeus 1758), treated with carcinogen for colon tumor induction. B-mode images were obtained, in vitro, from each animal (13 treated and 4 untreated) colon opened longitudinally and immersed in saline solution at room temperature. Prior to UBM inspection, all animals were also examined by colonoscopy. The layers of normal colon identified by UBM are: mucosa (hyperechoic), muscularis mucosae (hypoechoic), submucosa (hyperechoic) and muscularis externa (hypoechoic). UBM images of colon lesions presented structures corresponding to tumors (hyperechoic), lymphoid hyperplasia (hypoechoic) and polypoid tumors (hyperechoic). Additionally, tumoral lesion invasion through the colon was also identified. When compared with histopathologic analysis, all colon lesions detected by UBM were confirmed, while colonoscopic findings had two false negatives.

Study of superficial basal cell carcinomas and Bowen disease by qualitative and quantitative ultrasound biomicroscopy approach.

In the present work the ultrasound biomicroscopy (UBM) technique is applied in the study of cutaneous cell carcinomas in vitro, including superficial basal cell carcinomas (BCC) and Bowen disease (BD) cases. The evaluation was made by qualitative observation of UBM images, and by quantitative computation of integrated backscatter coefficient (IBC), obtained with a system working at a central frequency of 45 MHz. The characteristic histological structures for each studied tumor type were well identified in the images. The IBC values observed in the two carcinoma types inside the affected region, were different between them, next to 10(-4) [Sr(-1).mm(-1)] for superficial BCC tissues, and to 10(-5) [Sr(-1).mm(-1)1] for BD tissues; moreover, in the deeper dermis (slight affected region) the backscatter was next to 10(-3) [Sr(-1).mm(-1)] for both tissue groups, and agrees with the values obtained for healthy skin both, in this study and in previous works. The results here obtained encourage the continuation of the work, with a higher number of samples, attempting to obtain more significant results.

Ultrasound Biomicroscopy for In vivo architectural characterization of gastrocnemius muscle from rats.

This work applies the Ultrasound Biomicroscopy (UBM) technique to quantify the pennation angle (PA) and muscle thickness (MT) of rats' gastrocnemius muscle and to determine the reliability of these measurements. UBM (40MHz) images of five Wistar female rats were acquired at two ankle positions (neutral and full extension) and in two different days. A total of 320 images were processed to quantify PA and MT and a statistical analysis assessed data variability and reliability. The coefficients of variation were 9.37 and 3.97% for PA and MT, respectively, for the ankle at full extension and 15.41 and 4.99% for the ankle at neutral position. Pearson correlation between two repeated measurements in the same image were 0.93 and 0.99 for PA and MT, respectively. The results indicate that UBM is suitable for quantitative muscle architectural characterization and can be used in future muscle biomechanical studies.

In vitro ultrasound biomicroscopic imaging of colitis in rats.

OBJECTIVE: The purpose of this study was to show the feasibility of 50-MHz ultrasound biomicroscopy (UBM) to image the rat colon. METHODS: B-mode images were obtained from ex vivo colon samples (n = 4) collected from Rattus norvegicus (Berkenhout, 1769) rats, with 2,4,6-trinitrobenzene sulfonic acid-induced colitis in 3 of them. Left colon rectangular fragments (5 x 5 mm) were obtained after necropsy, and UBM images were acquired with the samples immersed in saline at 37 degrees C. All layers of the normal intestinal wall were analyzed according to their thickness and the presence of uneven bowel mucosa (ulcers). The folds and layers detected by UBM were correlated with histopathologic analysis. RESULTS: The 4 layers of the normal colon were identified on the UBM images: the mucosa (hyperechoic), muscularis mucosae (hypoechoic), submucosa (hyperechoic), and muscularis externa (hypoechoic). On 2 UBM images, superficial ulcers were detected, approximately 0.5 mm in size, with intestinal involvement limited to the mucosa. The histopathologic analysis verified enlargement of submucosa layers due to an edema associated with sub-mucosa leukocyte infiltration. On 1 UBM image, it was possible to detect a deep ulcer, which was confirmed by the light microscopic analysis. CONCLUSIONS: An ultrasound imaging system was scaled and optimized to visualize the rat colon. Ultrasound biomicroscopy provided axial and lateral resolutions close to 25 and 45 mum, respectively, and adequate penetration depth to visualize the whole thickness of an inflamed colon. The system identified the colon layers and was able to detect mural changes and superficial ulcers on the order of 500 mum.

A method to identify acoustic reverberation in multilayered homogeneous media.

The presence of reverberation is a source of artifacts that can hinder the analysis of ultrasound signals and images. Besides compromising image generation, these artifacts can introduce errors in the quantitative parameter estimation in fields such as material and biological tissue characterization. A method that allows the separation between the first reflection on an interface and all the other reflections from the same interface (reverberation) could improve the quality of these images as well as the precision and accuracy in quantitative results. This work presents an algorithm for the identification of reverberating echoes in multilayered media, based on the comparison of their power spectra (estimated via FFT), through a least mean square approach, and on the temporal relationship among them. It considers that the global effect from attenuation, reflection and transmission coefficients for each layer causes spectral differences that could differentiate echoes that pass through one layer or another. The results of 10 simulations and of 60 experiments, carried out with 6 different phantoms (10 experiments with each one) are presented and discussed. It was found that the algorithm provided a correct identification for 85% of the simulated and 86.6% of the experimental echoes collected from the 60 experiments.

Ultrasound characterization of coronary artery wall in vitro using temperature-dependent wave speed.

Temperature dependence of the speed of sound, partial partial differential c/partial partial differential T, is examined as a parameter to characterize tissue-equivalent phantoms and coronary artery tissue in vitro. The experimental system comprises an ultrasound biomicroscope, operating at center frequency of 50 MHz, and a temperature controlled micropositioning sample cell. Radio frequency (RF) backscattered signals were recorded, with a digital oscilloscope, from 64 independent positions and at 5 temperatures starting at 31 degrees C (phantom) and 36 degrees C (tissue) in steps of one degree. Time shift per degree Celsius (delta t/delta T) was obtained with a correlation technique applied between gated sections of two RF-signals collected with one degree temperature difference from the same location in the sample. The average (delta t/delta T), calculated for every position of the gated sections along the propagation axis of the ultrasound beam, has the slope proportional to the difference between the linear coefficient of thermal expansion and the thermal sensitivity of the speed of sound. Calibration measurements of partial partial differential c/partial partial differential T, made with single- and three-layer tissue equivalent phantoms, correlated well (r > or = 0.91) with those measured by the time-of-flight substitution method. The partial partial differential c/partial partial differential T was estimated for the three layers on the wall of eight samples of human coronary arteries, obtained at autopsy from four individuals. The partial partial differential c/partial partial differential T for the intima layers decreases as the disease progresses from mild intimal thickening to a more advanced atherosclerosis.

Ultrasonic wave speed measurement using the time-delay profile of rf-backscattered signals: simulation and experimental results.

Conventional methods determine the ultrasonic wave speed measuring the medium path length propagated by a pulsed wave and the corresponding time-of-flight. In this work, the wave speed is determined without the need of the path length. A transmit transducer sends a pulsed wave into the medium (wave speed constant along the beam axis) and the backscattered signal is collected by a hydrophone placed at two distinct positions near the transmitted beam. The time-delay profile, between gated windows of the two rf-signals received by the hydrophone, is determined using a cross-correlation method. Also, a theoretical time-delay profile is determined considering the wave speed as a parameter. The estimated wave speed is obtained upon minimization of the rms error between theoretical and experimental time-delay profiles. A PZT conically focused transmitting transducer with center frequency of 3.3 MHz, focal depth of 30 mm, and beam full width (-3 dB) of 2 mm at the focus was used together with a PZT hydrophone (0.8 mm of aperture). The method was applied to three phantoms (wave speed of 1220, 1540, and 1720 m/s) and, in vitro, to fresh bovine liver sample, immersed in a temperature-controlled water bath. The results present a relative speed error less than 3% when compared with the sound speed obtained by a conventional method.

Analise de mutações somáticas dos genes APP, presenilina 1 e 2, em tecido encefálico na doença de Alzheimer / Somatic mutationals analysis of genes APP, presenilin 1 and 2, in encephalic tissue in Alzheimer's disease

As bases moleculares da forma esporadica da doenca de Alzheimer (DA) permanecem ainda desconhecidas. Nos formulamos a hipotese de que, em alguns casos esporadicos de DA, uma mutacao somatica nos genes da proteina precursora amiloide (APP), da presenilina 1 (PS-1) e 2 (STM2) (genes envolvidos na DA forma familiar) em uma celula embrionaria comprometida com o desenvolvimento neuronal, pode resultar em fenotipo da DA. Usando a tecnica de PCR, eletroforese em gel de gradiente desnaturante (DGGE), analise de restricao e sequenciamento direto de DNA, nos analisamos esses genes em 99 tecidos encefalicos de pacientes com DA comprovada histologicamente. Uma amostra de tecido encefalico mostrou uma mutacao no gene PS-1 (His 163 Arg), que mais tarde foi demonstrada ser uma mutacao de celulas germinativas. Nenhuma outra anormalidade de migracao foi demonstrada, em qualquer amostra, nos exons 16 ou 17 do gene APP, nos exons codificadores da PS-1 ou qualquer padrao anormal de digestao pela analise de restricao no gene PS-2...

Determinaçäo de alteraçöes no tempo de coagulaçäo em funçäo da intensidade ultra-sônica irradiada no plasma sanguíneo / Determination of changes in coagulation time in irradiated ultrasound intensity function in blood plasm

Este artigo apresenta um estudo experimental para avaliar a faixa de frequência e intensidade ultra-sônica que pode ser usada em aparatos de medição de tempo de coagulação por ultra-som, sobre uma amostra de plasma, sem que resulte em interferência no processo de coagulação.

This article presents an experimental study to evaluate the ultrasonic frequency range and intensity generated by a set of transducers that can be used in a coagulation time measurement device by ultrasound, on a sample of plasma, without causing any interference on the coagulation process.

Método ultra-sônico para a caracterizaçäo do processo de coagulaçäo do plasma normal e com deficiência de fator VIII: C / Ultrasound method for the caracterization of coagulation process of normal plasm with factor III deficiency: C

Este artigo descreve uma metodologia para a obtenção de um sinal ultra-sônico que contém informações sobre o processo de coagulação, de uma amostra de plasma sangüíneo padrão-nível 1. São apresentados e analisados resultados experimentais iniciais do Tempo de Tromboplastina Parcial Ativado (TTPa), de um grupo de amostras de Plasmas Normal e Deficiente em Fat.VIII:C, em função das intensidades ultra-sônicas utilizadas.

This paper describes an ultrasonic method to extract information from plasma clotting. Initial results of time coagulation measurements of normal and haemophiliac standard plasma samples are presented for different ultrasonic field intensities and discussed.

Modelo de propagaçäo de ultra-som po acústica geométrica aplicado à transdutor linear focalizado / Ultrasound measuring model for geometrical acoustic applied focalized linear transducer

Este trabalho apresenta um modelo matemático baseado em acústica geométrica, que estima a espessura e velocidade de propagação do ultra-som de um meio multicamadas a partir dos atrasos temporais de uma frente de onda acústica medidos entre os elementos piezelétricos de um transdutor linear. São apresentados e discutidos os resultados de um experimento com duas camadas: água+PVC.

This work presents a geometrical acoustics model which estimates both thickness and speed of ultrasound by measuring time delays of an acoustic wave between piezoelectric elements of a linear array. Results of an experiment using a two layer phantom (water+PCV) are presented and discussed

A influência do diagrama de radiaçäo de transdutores de ultra-som na estimativa de espessuras / Influency of radiation diagnosis of ultrasound transducers in estimates thickness

Este trabalho apresenta uma comparação de desempenho de dois transdutores focalizados em um modelo de Acústica Geométrica para estimar espessura em meios multicamadas. São apresentados resultados experimentais com transdutores de 1,9 MHz e 8,65 MHz. É feita a análise de camada (água), com espessuras comparáveis em ambos os experimentos. Os resultados apresentaram melhor acurácia (<5 por cento) e precisão (<5 por cento) para os experimentos com o transdutor de 8,65 MHz utilizando uma salva de excitação longa. São discutidas a influência dos diagramas de radiação e da largura da salva de excitação.

This work presents a performance comparison of two focused transducers with a Geometrical Acoustics model that estimates thickness in layered media. Experimental results with transducers of 1.9 MHz and 8.65 MHz are available. We present the estimates for one layer (water) of cornparable thicknesses for both experiments. We obtained better accuracy (< 5%) and precision (<5%) with the 8.65 MHz transducer with a long transmission burst. The influence of the radiation diagram and the width of the excitation burst is investigated.

Novo método para identificaçäo de ecos reais e ecos de reverberaçäo em meios multicamadas / New method for identification of real and reverberation echoes in layered media

Este trabalho visa testar a potencialidade de um método de mínimos quadrados na diferenciação entre ecos reais e ecos de reverberação. Como exemplo, serão analisados os resultados de um experimento.

This work intends to test the potentiality of a minimum square method to differ real echoes from reverberation ones. As an example, the results of an experiment will be analysed.

Otimizaçäo da camada de retaguarda para transdutores ultra-sônicos de alta frequência / Optimization of rear layer for high frequency ultrasonic transducers

As especificações técnicas de um transdutor de ultra-som são funções das propriedades físicas do elemento piezoelétrico e das condições de contorno acústicas e elétricas entre as estruturas a ele associadas. O projeto de um transdutor envolve o perfeito equacionamento entre necessidade construtivas antagônicas, podendo a otimização de um destes fatores, ocasionar a deterioração dos outros. É apresentada, neste artigo, uma simulação computacional de uma camada de retaguarda ("backing") que visa maximizar a resolução axial sem prejudicar as demais características do transdutor.

The technical specifications of an ultrasound transducer are functions of the physical properties of the piezoelectric element and the acoustic and electrical contour conditions of the associated structures. The project of an ultrasound probe needs the antagonistic constructional requirements to be perfectly matched, otherwise the optimization of one of these factors may degrade the others. This work presents a computational simulation for a backing layer to maximize the axial resolution and preserve the other characteristics of the transducer