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1.
Int J Hyperthermia ; 39(1): 1283-1293, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36162814

RESUMO

BACKGROUND: In stereotactic radiosurgery, isodose lines must be considered to determine how surrounding tissue is affected. In thermal ablative therapy, such as laser interstitial thermal therapy (LITT), transcranial MR-guided focused ultrasound (tcMRgFUS), and needle-based therapeutic ultrasound (NBTU), how the surrounding area is affected has not been well studied. OBJECTIVE: We aimed to quantify the transition zone surrounding the ablation core created by magnetic resonance-guided robotically-assisted (MRgRA) delivery of NBTU using multi-slice volumetric 2-D magnetic resonance thermal imaging (MRTI) and subsequent characterization of the resultant tissue damage using histopathologic analysis. METHODS: Four swine underwent MRgRA NBTU using varying duration and wattage for treatment delivery. Serial MRI images were obtained, and the most representative were overlaid with isodose lines and compared to brain tissue acquired postmortem which underwent histopathologic analysis. These results were also compared to predicted volumes using a finite element analysis model. Contralateral brain tissue was used for control data. RESULTS: Intraoperative MRTI thermal isodose contours were characterized and comprehensively mapped to post-operative MRI images and qualitatively compared with histological tissue sections postmortem. NBTU 360° ablations induced smaller lesion volumes (33.19 mm3; 120 s, 3 W; 30.05 mm3, 180 s, 4 W) versus 180° ablations (77.20 mm3, 120 s, 3 W; 109.29 mm3; 180 s; 4 W). MRTI/MRI overlay demonstrated the lesion within the proximal isodose lines. The ablation-zone was characterized by dense macrophage infiltration and glial/neuronal loss as demonstrated by glial fibrillary acidic protein (GFAP) and neurofilament (NF) absence and avid CD163 staining. The transition-zone between lesion and normal brain demonstrated decreased macrophage infiltration and measured ∼345 microns (n - 3). We did not detect overt hemorrhages or signs of edema in the adjacent spared tissue. CONCLUSION: We successfully performed MRgRA NBTU ablation in swine and demonstrated minimal histologic changes extended past the ablation-zone. The lesion was characterized by macrophage infiltration and glial/neuronal loss which decreased through the transition-zone.


Assuntos
Encéfalo , Terapia por Ultrassom , Animais , Encéfalo/diagnóstico por imagem , Encéfalo/cirurgia , Proteína Glial Fibrilar Ácida , Fígado , Imageamento por Ressonância Magnética/métodos , Suínos
2.
Neuromodulation ; 25(4): 504-510, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35667768

RESUMO

OBJECTIVE: Chronic pain affects 7%-10% of Americans, occurs more frequently and severely in females, and available treatments have been shown to have less efficacy in female patients. Preclinical models addressing sex-specific treatment differences in the treatment of chronic pain have been limited. Here we examine the sex-specific effects of low intensity focused ultrasound (liFUS) in a modified sciatic nerve injury (SNI) model. MATERIALS AND METHODS: A modified SNI performed by ligating the common peroneal nerve (CPN) was used to measure sensory, behavioral pain responses, and nerve conduction studies in female and male rats, following liFUS of the L5 dorsal root ganglion. RESULTS: Using the same dose of liFUS in females and males of the same weight, CPN latency immediately after treatment was increased for 50 min in females compared to 25 min in males (p < 0.001). Improvements in mechanical pain thresholds after liFUS lasted significantly longer in females (seven days; p < 0.05) compared to males (three days; p < 0.05). In females, there was a significant improvement in depression-like behavior as a result of liFUS (N = 5; p < 0.01); however, because males never developed depression-like behavior there was no change after liFUS treatment. CONCLUSIONS: Neuromodulation with liFUS has a greater effect in female rats on CPN latency, mechanical allodynia duration, and depression-like behavior. In order to customize neuromodulatory techniques for different patient phenotypes, it is essential to understand how they may alter sex-specific pathophysiologies.


Assuntos
Dor Crônica , Neuralgia , Traumatismos dos Nervos Periféricos , Animais , Modelos Animais de Doenças , Feminino , Humanos , Hiperalgesia/etiologia , Hiperalgesia/terapia , Masculino , Neuralgia/terapia , Traumatismos dos Nervos Periféricos/terapia , Nervo Fibular/diagnóstico por imagem , Nervo Fibular/lesões , Ratos
3.
Int J Hyperthermia ; 38(1): 907-915, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34148489

RESUMO

BACKGROUND: High-intensity focused ultrasound (HIFU) serves as a noninvasive stereotactic system for the ablation of brain metastases; however, treatments are limited to simple geometries and energy delivery is limited by the high acoustic attenuation of the calvarium. Minimally-invasive magnetic resonance-guided robotically-assisted (MRgRA) needle-based therapeutic ultrasound (NBTU) using multislice volumetric 2-D magnetic resonance thermal imaging (MRTI) overcomes these limitations and has potential to produce less collateral tissue damage than current methods. OBJECTIVE: To correlate multislice volumetric 2-D MRTI volumes with histologically confirmed regions of tissue damage in MRgRA NBTU. METHODS: Seven swine underwent a total of 8 frontal MRgRA NBTU lesions. MRTI ablation volumes were compared to histologic tissue damage on brain sections stained with 2,3,5-triphenyltetrazolium chloride (TTC). Bland-Altman analyses and correlation trends were used to compare MRTI and TTC ablation volumes. RESULTS: Data from the initial and third swine's ablations were excluded due to sub-optimal tissue staining. For the remaining ablations (n = 6), the limits of agreement between the MRTI and histologic volumes ranged from -0.149 cm3 to 0.252 cm3 with a mean difference of 0.052 ± 0.042 cm3 (11.1%). There was a high correlation between the MRTI and histology volumes (r2 = 0.831) with a strong linear relationship (r = 0.868). CONCLUSION: We used a volumetric MRTI technique to accurately track thermal changes during MRgRA NBTU in preparation for human trials. Improved volumetric coverage with MRTI enhanced our delivery of therapy and has far-reaching implications for focused ultrasound in the broader clinical setting.


Assuntos
Neoplasias Encefálicas , Ablação por Ultrassom Focalizado de Alta Intensidade , Terapia por Ultrassom , Animais , Encéfalo/diagnóstico por imagem , Encéfalo/cirurgia , Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/cirurgia , Imageamento por Ressonância Magnética , Espectroscopia de Ressonância Magnética , Suínos
4.
Neurosurg Focus ; 44(2): E11, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29385926

RESUMO

Currently, treatment of brain tumors is limited to resection, chemotherapy, and radiotherapy. Thermal ablation has been recently explored. High-intensity focused ultrasound (HIFU) is being explored as an alternative. Specifically, the authors propose delivering HIFU internally to the tumor with an MRI-guided robotic assistant (MRgRA). The advantage of the authors' interstitial device over external MRI-guided HIFU (MRgHIFU) is that it allows for conformal, precise ablation and concurrent tissue sampling. The authors describe their workflow for MRgRA HIFU delivery.


Assuntos
Neoplasias Encefálicas/diagnóstico por imagem , Neoplasias Encefálicas/cirurgia , Imageamento por Ressonância Magnética/métodos , Procedimentos Cirúrgicos Robóticos/métodos , Ultrassonografia de Intervenção/métodos , Humanos , Terapia a Laser/instrumentação , Terapia a Laser/métodos , Procedimentos Cirúrgicos Robóticos/instrumentação
5.
Neurosurg Focus ; 44(2): E13, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29385920

RESUMO

OBJECTIVE Minimally invasive procedures may allow surgeons to avoid conventional open surgical procedures for certain neurological disorders. This paper describes the iterative process for development of a catheter-based ultrasound thermal therapy applicator. METHODS Using an ultrasound applicator with an array of longitudinally stacked and angularly sectored tubular transducers within a catheter, the authors conducted experimental studies in porcine liver, in vivo and ex vivo, in order to characterize the device performance and lesion patterns. In addition, they applied the technique in a rodent model of Parkinson's disease to investigate the feasibility of its application in brain. RESULTS Thermal lesions with multiple shapes and sizes were readily achieved in porcine liver. The feasibility of catheter-based focused ultrasound in the treatment of brain conditions was demonstrated in a rodent model of Parkinson's disease. CONCLUSIONS The authors show proof of principle of a catheter-based ultrasound system that can create lesions with concurrent thermode-based measurements.


Assuntos
Encéfalo/diagnóstico por imagem , Cateterismo/métodos , Procedimentos Cirúrgicos Minimamente Invasivos/métodos , Transtornos Parkinsonianos/diagnóstico por imagem , Ultrassonografia de Intervenção/métodos , Animais , Encéfalo/cirurgia , Transtornos Parkinsonianos/cirurgia , Ratos , Suínos
6.
J Ultrasound Med ; 34(8): 1373-83, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26206823

RESUMO

OBJECTIVES: Quantitative ultrasound estimates such as the frequency-dependent backscatter coefficient (BSC) have the potential to enhance noninvasive tissue characterization and to identify tumors better than traditional B-mode imaging. Thus, investigating system independence of BSC estimates from multiple imaging platforms is important for assessing their capabilities to detect tissue differences. METHODS: Mouse and rat mammary tumor models, 4T1 and MAT, respectively, were used in a comparative experiment using 3 imaging systems (Siemens, Ultrasonix, and VisualSonics) with 5 different transducers covering a range of ultrasonic frequencies. RESULTS: Functional analysis of variance of the MAT and 4T1 BSC-versus-frequency curves revealed statistically significant differences between the two tumor types. Variations also were found among results from different transducers, attributable to frequency range effects. At 3 to 8 MHz, tumor BSC functions using different systems showed no differences between tumor type, but at 10 to 20 MHz, there were differences between 4T1 and MAT tumors. Fitting an average spline model to the combined BSC estimates (3-22 MHz) demonstrated that the BSC differences between tumors increased with increasing frequency, with the greatest separation above 15 MHz. Confining the analysis to larger tumors resulted in better discrimination over a wider bandwidth. CONCLUSIONS: Confining the comparison to higher ultrasonic frequencies or larger tumor sizes allowed for separation of BSC-versus-frequency curves from 4T1 and MAT tumors. These constraints ensure that a greater fraction of the backscattered signals originated from within the tumor, thus demonstrating that statistically significant tumor differences were detected.


Assuntos
Interpretação de Imagem Assistida por Computador/instrumentação , Interpretação de Imagem Assistida por Computador/métodos , Neoplasias Mamárias Animais/diagnóstico por imagem , Ultrassonografia/instrumentação , Ultrassonografia/métodos , Animais , Linhagem Celular Tumoral , Desenho de Equipamento , Análise de Falha de Equipamento , Camundongos , Camundongos Endogâmicos BALB C , Ratos , Ratos Sprague-Dawley , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Especificidade da Espécie
7.
J Acoust Soc Am ; 138(6): EL493-7, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26723356

RESUMO

Ultrasound-stimulated microbubbles (MBs) were demonstrated to enhance cell kill from hyperthermia. Definity MBs were injected into wells containing 4T1 cells in culture media and scanned with 1-MHz ultrasound, an exposure duration of 30 s and a negative pressure of 0.5 or 1.3 MPa. Some cell samples were placed in a water bath heated to 42 °C for 5 min. Cell death was quantified. When combining MBs, ultrasound at 1.3 MPa and hyperthermia, more than 58.8% ± 7.21% of cells were nonviable. When exposed to hyperthermia alone or exposure to MBs and ultrasound but no hyperthermia, cell death was less than 10.1% ± 6.96% and 30.1% ± 10.8%, respectively.


Assuntos
Meios de Contraste/química , Fluorocarbonos/química , Hipertermia Induzida , Neoplasias Mamárias Experimentais/patologia , Microbolhas , Terapia por Ultrassom/métodos , Ondas Ultrassônicas , Animais , Morte Celular , Linhagem Celular Tumoral , Sobrevivência Celular , Feminino , Camundongos
8.
Ultrason Imaging ; 36(4): 239-55, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24970857

RESUMO

Quantitative ultrasound (QUS) imaging is hypothesized to map temperature elevations induced in tissue with high spatial and temporal resolution. To test this hypothesis, QUS techniques were examined to monitor high-intensity focused ultrasound (HIFU) exposure of tissue. In situ experiments were conducted on mammary adenocarcinoma tumors grown in rats and lesions were formed using a HIFU system. A thermocouple was inserted into the tumor to provide estimates of temperature at one location. Backscattered time-domain waveforms from the tissue during exposure were recorded using a clinical ultrasonic imaging system. Backscatter coefficients were estimated using a reference phantom technique. Two parameters were estimated from the backscatter coefficient (effective scatterer diameter (ESD) and effective acoustic concentration (EAC). The changes in the average parameters in the regions corresponding to the HIFU focus over time were correlated to the temperature readings from the thermocouple. The changes in the EAC parameter were consistently correlated to temperature during both heating and cooling of the tumors. The changes in the ESD did not have a consistent trend with temperature. The mean ESD and EAC before exposure were 120 ± 16 µm and 32 ± 3 dB/cm3, respectively, and changed to 144 ± 9 µm and 51 ± 7 dB/cm3, respectively, just before the last HIFU pulse was delivered to the tissue. After the tissue cooled down to 37 °C, the mean ESD and EAC were 126 ± 8 µm and 35 ± 4 dB/cm3, respectively. Peak temperature in the range of 50-60 °C was recorded by a thermocouple placed just behind the tumor. These results suggest that QUS techniques have the potential to be used for non-invasive monitoring of HIFU exposure.


Assuntos
Adenocarcinoma/diagnóstico por imagem , Adenocarcinoma/cirurgia , Ablação por Ultrassom Focalizado de Alta Intensidade/instrumentação , Neoplasias Mamárias Experimentais/diagnóstico por imagem , Neoplasias Mamárias Experimentais/cirurgia , Animais , Linhagem Celular Tumoral , Desenho de Equipamento , Feminino , Ratos , Ratos Endogâmicos F344 , Ultrassonografia
9.
J Acoust Soc Am ; 134(2): 1559-68, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23927196

RESUMO

Fischer 344 rats with subcutaneous mammary adenocarcinoma tumors were exposed to therapeutic ultrasound at one of three exposure levels (335, 360, and 502 W/cm(2) spatial-peak temporal-average intensity). Quantitative ultrasound estimates were generated from ultrasound radio frequency (RF) data from tumors before and after high-intensity focused ultrasound treatment. Treatment outcome was independently assessed by triphenyl tetrazolium chloride (TTC) staining, histological analysis by a pathologist, and thermocouple data. The average backscatter coefficient (BSC) and integrated backscatter coefficient (IBSC) were estimated before and after therapeutic ultrasound exposure for each tumor from RF data collected using clinical (Ultrasonix Sonix RP) and small-animal (Visualsonics Vevo 2100) array systems. Changes in the BSC with treatment were comparable to inter-sample variation of untreated tumors, but statistically significant differences in the change in the IBSCs were observed when comparing the exposures collectively (p < 0.10 for Sonix RP, p < 0.05 for Vevo 2100). Several exposure levels produced statistically significant differences in the change in IBSC when examined pair-wise, including two exposures having similar intensities (p < 0.05, Vevo 2100). A comparison of the IBSC results with temperature data, histology, and TTC staining revealed that the BSC was not always sensitive to thermal insult and that peak exposure pressure appeared to correlate with observed BSC increases.


Assuntos
Adenocarcinoma/cirurgia , Neoplasias da Mama/cirurgia , Ablação por Ultrassom Focalizado de Alta Intensidade , Adenocarcinoma/diagnóstico por imagem , Adenocarcinoma/patologia , Animais , Temperatura Corporal , Neoplasias da Mama/diagnóstico por imagem , Neoplasias da Mama/patologia , Feminino , Ablação por Ultrassom Focalizado de Alta Intensidade/efeitos adversos , Ablação por Ultrassom Focalizado de Alta Intensidade/métodos , Pressão , Ratos , Ratos Endogâmicos F344 , Espalhamento de Radiação , Som , Ultrassonografia
10.
Ultrasound Med Biol ; 49(9): 2095-2102, 2023 09.
Artigo em Inglês | MEDLINE | ID: mdl-37365065

RESUMO

OBJECTIVE: B-lines are a ring-down artifact of lung ultrasound that arise with increased alveolar water in conditions such as pulmonary edema and infectious pneumonitis. Confluent B-line presence may signify a different level of pathology compared with single B-lines. Existing algorithms aimed at B-line counting do not distinguish between single and confluent B-lines. The objective of this study was to test a machine learning algorithm for confluent B-line identification. METHODS: This study used a subset of 416 clips from 157 subjects, previously acquired in a prospective study enrolling adults with shortness of breath at two academic medical centers, using a hand-held tablet and a 14-zone protocol. After exclusions, random sampling generated a total of 416 clips (146 curvilinear, 150 sector and 120 linear) for review. A group of five experts in point-of-care ultrasound blindly evaluated the clips for presence/absence of confluent B-lines. Ground truth was defined as majority agreement among the experts and used for comparison with the algorithm. RESULTS: Confluent B-lines were present in 206 of 416 clips (49.5%). Sensitivity and specificity of confluent B-line detection by algorithm compared with expert determination were 83% (95% confidence interval [CI]: 0.77-0.88) and 92% (95% CI: 0.88-0.96). Sensitivity and specificity did not statistically differ between transducers. Agreement between algorithm and expert for confluent B-lines measured by unweighted κ was 0.75 (95% CI: 0.69-0.81) for the overall set. CONCLUSION: The confluent B-line detection algorithm had high sensitivity and specificity for detection of confluent B-lines in lung ultrasound point-of-care clips, compared with expert determination.


Assuntos
Pulmão , Edema Pulmonar , Adulto , Humanos , Estudos Prospectivos , Pulmão/diagnóstico por imagem , Algoritmos , Ultrassonografia/métodos , Aprendizado de Máquina
11.
J Acoust Soc Am ; 132(1): 533-43, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22779499

RESUMO

Ultrasonic attenuation is important not only as a parameter for characterizing tissue but also for compensating other parameters that are used to classify tissues. Several techniques have been explored for estimating ultrasonic attenuation from backscattered signals. In the present study, a technique is developed to estimate the local ultrasonic attenuation coefficient by analyzing the time domain backscattered signal. The proposed method incorporates an objective function that combines the diffraction pattern of the source/receiver with the attenuation slope in an integral equation. The technique was assessed through simulations and validated through experiments with a tissue mimicking phantom and fresh rabbit liver samples. The attenuation values estimated using the proposed technique were compared with the attenuation estimated using insertion loss measurements. For a data block size of 15 pulse lengths axially and 15 beamwidths laterally, the mean attenuation estimates from the tissue mimicking phantoms were within 10% of the estimates using insertion loss measurements. With a data block size of 20 pulse lengths axially and 20 beamwidths laterally, the error in the attenuation values estimated from the liver samples were within 10% of the attenuation values estimated from the insertion loss measurements.


Assuntos
Fígado/fisiologia , Ultrassom , Animais , Masculino , Modelos Biológicos , Imagens de Fantasmas , Coelhos , Espalhamento de Radiação , Espectrografia do Som , Transdutores
12.
J Acoust Soc Am ; 132(1): EL43-8, 2012 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-22779571

RESUMO

In this article, the effects of uniaxial compressive loading on the ultrasonic scattering from polycrystalline grains are shown for 10 MHz ultrasound in annealed, 1018 steel. The results show a decreasing value of the stress-dependent backscatter coefficient for normal incident ultrasound when the compression loading is perpendicular to the scattering direction. The change due to scattering is about 2 orders of magnitude greater than changes observed by others using ultrasonic wavespeed measurements. It is anticipated that this research can serve as the basis for many methods associated with nondestructive determination of stress in structural materials.

13.
J Acoust Soc Am ; 132(3): 1319-24, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22978860

RESUMO

A key step toward implementing quantitative ultrasound techniques in a clinical setting is demonstrating that parameters such as the ultrasonic backscatter coefficient (BSC) can be accurately estimated independent of the clinical imaging system used. In previous studies, agreement in BSC estimates for well characterized phantoms was demonstrated across different laboratory systems. The goal of this study was to compare the BSC estimates of a tissue mimicking sample measured using four clinical scanners, each providing RF echo data in the 1-15 MHz frequency range. The sample was previously described and characterized with single-element transducer systems. Using a reference phantom for analysis, excellent quantitative agreement was observed across the four array-based imaging systems for BSC estimates. Additionally, the estimates from data acquired with the clinical systems agreed with theoretical predictions and with estimates from laboratory measurements using single-element transducers.


Assuntos
Imagens de Fantasmas , Ultrassom/instrumentação , Ultrassonografia/instrumentação , Ágar , Desenho de Equipamento , Géis , Vidro , Modelos Teóricos , Espalhamento de Radiação , Processamento de Sinais Assistido por Computador , Transdutores
14.
Int J Occup Saf Ergon ; 18(4): 521-30, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23294656

RESUMO

This study was undertaken among 100 randomly selected bus conductors from 2 routes. A questionnaire study based on the modified Nordic musculoskeletal questionnaire, assessment of physical and physiological parameters, analysis of working postures and a detailed work study were performed. The analysis revealed that conductors had a work schedule of 16-18 h each day; the duration of work could vary from 15 to 20 days at a stretch. Discomfort leading to musculoskeletal disorders mainly affecting the leg (93.3%), knee (83.3%), shoulder (80%) and back areas (56.7%) had the highest 12-month prevalence rates and increased day by day. The conductors also suffered from extreme physiological stress due to prolonged working hours in hazardous standing posture conditions, excessive work pressure and minimum rest between trips. Consequently, all those factors affected their health and work performance.


Assuntos
Veículos Automotores , Doenças Musculoesqueléticas/epidemiologia , Doenças Profissionais/epidemiologia , Postura , Adulto , Pressão Sanguínea , Pesos e Medidas Corporais , Ergonomia , Frequência Cardíaca , Humanos , Índia/epidemiologia , Masculino , Pessoa de Meia-Idade , Prevalência , Inquéritos e Questionários , Fatores de Tempo
15.
J Acoust Soc Am ; 129(5): 2903-11, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21568393

RESUMO

The ultimate goal of quantitative ultrasound (QUS) imaging methods based on backscatter coefficient (BSC) estimates is to obtain system-independent structural information about samples. In the current study, three BSC estimation methods were compared and evaluated using the same backscattered pressure datasets in order to assess their consistency. BSC estimates were obtained from two phantoms with embedded glass spheres and compared to theoretical BSCs calculated using size distributions estimated using optical microscopy. Effective scatterer diameter and concentration estimates of the glass spheres were also obtained from the estimated BSCs. One estimation method needed to be compensated by more than an order of magnitude in amplitude in order to produce BSCs comparable to the other two methods. All calibration methods introduced different frequency-dependent effects, which could have noticeable effects on the bias of QUS estimates derived from experimental BSCs. Although in most cases the experimental QUS estimates obtained with all three methods were observed to differ by less than 10%, larger differences are expected depending on both the pressure focusing gain of the transducer (proportional to the ratio of the square of the aperture radius to the product of the wavelength and focal length) and ka range used in the estimation.


Assuntos
Transdutores , Ultrassonografia/instrumentação , Ágar , Algoritmos , Desenho de Equipamento , Análise de Fourier , Matemática , Microesferas , Tamanho da Partícula , Imagens de Fantasmas
16.
J Acoust Soc Am ; 130(4): 2203-11, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21973375

RESUMO

Quantitative ultrasound (QUS) is an imaging technique that can be used to quantify tissue microstructure giving rise to scattered ultrasound. Other ultrasonic properties, e.g., sound speed and attenuation, of tissues have been estimated versus temperature elevation and found to have a dependence with temperature. Therefore, it is hypothesized that QUS parameters may be sensitive to changes in tissue microstructure due to temperature elevation. Ultrasonic backscatter experiments were performed on tissue-mimicking phantoms and freshly excised rabbit and beef liver samples. The phantoms were made of agar and contained either mouse mammary carcinoma cells (4T1) or chinese hamster ovary cells (CHO) as scatterers. All scatterers were uniformly distributed spatially at random throughout the phantoms. All the samples were scanned using a 20-MHz single-element f/3 transducer. Quantitative ultrasound parameters were estimated from the samples versus increases in temperature from 37 °C to 50 °C in 1 °C increments. Two QUS parameters were estimated from the backscatter coefficient [effective scatterer diameter (ESD) and effective acoustic concentration (EAC)] using a spherical Gaussian scattering model. Significant increases in ESD and decreases in EAC of 20%-40% were observed in the samples over the range of temperatures examined. The results of this study indicate that QUS parameters are sensitive to changes in temperature.


Assuntos
Fígado/diagnóstico por imagem , Temperatura , Ultrassom , Ágar , Animais , Células CHO , Bovinos , Linhagem Celular Tumoral , Cricetinae , Cricetulus , Feminino , Masculino , Camundongos , Modelos Biológicos , Movimento (Física) , Imagens de Fantasmas , Coelhos , Espalhamento de Radiação , Som , Fatores de Tempo , Transdutores , Ultrassom/instrumentação , Ultrassonografia
17.
Spine (Phila Pa 1976) ; 46(3): E146-E152, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33399436

RESUMO

STUDY DESIGN: Experimental in-vivo animal study. OBJECTIVE: The aim of this study was to evaluate an Artificial Intelligence (AI)-enabled ultrasound imaging system's ability to detect, segment, classify, and display neural and other structures during trans-psoas spine surgery. SUMMARY OF BACKGROUND DATA: Current methodologies for intraoperatively localizing and visualizing neural structures within the psoas are limited and can impact the safety of lateral lumbar interbody fusion (LLIF). Ultrasound technology, enhanced with AI-derived neural detection algorithms, could prove useful for this task. METHODS: The study was conducted using an in vivo porcine model (50 subjects). Image processing and machine learning algorithms were developed to detect neural and other anatomic structures within and adjacent to the psoas muscle while using an ultrasound imaging system during lateral lumbar spine surgery (SonoVision,™ Tissue Differentiation Intelligence, USA). The imaging system's ability to detect and classify the anatomic structures was assessed with subsequent tissue dissection. Dice coefficients were calculated to quantify the performance of the image segmentation. RESULTS: The AI-trained ultrasound system detected, segmented, classified, and displayed nerve, psoas muscle, and vertebral body surface with high sensitivity and specificity. The mean Dice coefficient score for each tissue type was >80%, indicating that the detected region and ground truth were >80% similar to each other. The mean specificity of nerve detection was 92%; for bone and muscle, it was >95%. The accuracy of nerve detection was >95%. CONCLUSION: This study demonstrates that a combination of AI-derived image processing and machine learning algorithms can be developed to enable real-time ultrasonic detection, segmentation, classification, and display of critical anatomic structures, including neural tissue, during spine surgery. AI-enhanced ultrasound imaging can provide a visual map of important anatomy in and adjacent to the psoas, thereby providing the surgeon with critical information intended to increase the safety of LLIF surgery.Level of Evidence: N/A.


Assuntos
Inteligência Artificial/normas , Monitorização Neurofisiológica Intraoperatória/normas , Vértebras Lombares/diagnóstico por imagem , Modelos Animais , Músculos Psoas/diagnóstico por imagem , Algoritmos , Animais , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Processamento de Imagem Assistida por Computador/normas , Monitorização Neurofisiológica Intraoperatória/métodos , Vértebras Lombares/cirurgia , Aprendizado de Máquina/normas , Músculos Psoas/cirurgia , Reprodutibilidade dos Testes , Fusão Vertebral/métodos , Fusão Vertebral/normas , Suínos , Ultrassonografia/métodos , Ultrassonografia/normas
18.
J Neurosurg ; : 1-8, 2021 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-33862597

RESUMO

OBJECTIVE: The authors' laboratory has previously demonstrated beneficial effects of noninvasive low intensity focused ultrasound (liFUS), targeted at the dorsal root ganglion (DRG), for reducing allodynia in rodent neuropathic pain models. However, in rats the DRG is 5 mm below the skin when approached laterally, while in humans the DRG is typically 5-8 cm deep. Here, using a modified liFUS probe, the authors demonstrated the feasibility of using external liFUS for modulation of antinociceptive responses in neuropathic swine. METHODS: Two cohorts of swine underwent a common peroneal nerve injury (CPNI) to induce neuropathic pain. In the first cohort, pigs (14 kg) were iteratively tested to determine treatment parameters. liFUS penetration to the L5 DRG was verified by using a thermocouple to monitor tissue temperature changes and by measuring nerve conduction velocity (NCV) at the corresponding common peroneal nerve (CPN). Pain behaviors were monitored before and after treatment. DRG was evaluated for tissue damage postmortem. Based on data from the first cohort, a treatment algorithm was developed, parameter predictions were verified, and neuropathic pain was significantly modified in a second cohort of larger swine (20 kg). RESULTS: The authors performed a dose-response curve analysis in 14-kg CPNI swine. Specifically, after confirming that the liFUS probe could reach 5 cm in ex vivo tissue experiments, the authors tested liFUS in 14-kg CPNI swine. The mean ± SEM DRG depth was 3.79 ± 0.09 cm in this initial cohort. The parameters were determined and then extrapolated to larger animals (20 kg), and predictions were verified. Tissue temperature elevations at the treatment site did not exceed 2°C, and the expected increases in the CPN NCV were observed. liFUS treatment eliminated pain guarding in all animals for the duration of follow-up (up to 1 month) and improved allodynia for 5 days postprocedure. No evidence of histological damage was seen using Fluoro-Jade and H&E staining. CONCLUSIONS: The results demonstrate that a 5-cm depth can be reached with external liFUS and alters pain behavior and allodynia in a large-animal model of neuropathic pain.

19.
Neurosci Lett ; 757: 135977, 2021 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-34023413

RESUMO

BACKGROUND: Changes in inflammatory cytokine levels contribute to the induction and maintenance of neuropathic pain. We have shown that external low intensity focused ultrasound (liFUS) reduces allodynia in a common peroneal nerve injury (CPNI). Here, we investigate an underlying mechanism of action for this treatment and measure the effect of liFUS on inflammatory markers. METHODS: Male rats were divided into four groups: CPNI/liFUS, CPNI/shamliFUS, shamCPNI/liFUS, and shamCPNI/shamliFUS. Mechanical nociceptive thresholds were measured using Von Frey filaments (VFF) to confirm the absence/presence of allodynia at baseline, after CPNI, and after liFUS. Commercial microarray and ELISA assays were used to assess cytokine expression in the treated L5 dorsal root ganglion (DRG) and dorsal horn (DH) tissue 24 and 72 h after liFUS. RESULTS: VFF thresholds were significantly reduced following CPNI in both groups that received the injury (p < 0.001). After liFUS, only the CPNI/liFUS cohort showed a significant increase in mechanical thresholds (p < 0.001). CPNI significantly increased TNFa, IL6, CNTF, IL1b (p < 0.05 for all) levels in the DRG and DH, compared to baseline, consistent with previous work in sciatic nerve injury. LiFUS in CPNI rats resulted in a decrease in these cytokines in DRG 72 h post-therapy (TNFa, IL6, CNTF and IL1b, p < 0.001). In the DH, IL1b, CNTF, and TNFa (p < 0.05 for all) decreased 72 h after liFUS. CONCLUSION: We have demonstrated that liFUS modifies inflammatory cytokines in both DRG and DH in CPNI rats. These data provide evidence that liFUS, reverses the allodynic phenotype, in part, by altering inflammatory cytokine pathways.


Assuntos
Hiperalgesia/terapia , Neuralgia/terapia , Traumatismos dos Nervos Periféricos/complicações , Terapia por Ultrassom/métodos , Animais , Citocinas/metabolismo , Modelos Animais de Doenças , Gânglios Espinais/imunologia , Gânglios Espinais/metabolismo , Humanos , Hiperalgesia/diagnóstico , Hiperalgesia/imunologia , Masculino , Neuralgia/diagnóstico , Neuralgia/imunologia , Traumatismos dos Nervos Periféricos/imunologia , Traumatismos dos Nervos Periféricos/terapia , Nervo Fibular/lesões , Ratos , Ratos Sprague-Dawley , Transdução de Sinais/imunologia , Transdução de Sinais/efeitos da radiação , Corno Dorsal da Medula Espinal/imunologia , Corno Dorsal da Medula Espinal/metabolismo , Ondas Ultrassônicas
20.
J Ultrasound Med ; 29(7): 1117-23, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-20587435

RESUMO

OBJECTIVE: To translate quantitative ultrasound (QUS) from the laboratory into the clinic, it is necessary to demonstrate that the measurements are platform independent. Because the backscatter coefficient (BSC) is the fundamental estimate from which additional QUS estimates are calculated, agreement between BSC results using different systems must be demonstrated. This study was an intercomparison of BSCs from in vivo spontaneous rat mammary tumors acquired by different groups using 3 clinical array systems and a single-element laboratory scanner system. METHODS: Radio frequency data spanning the 1- to 14-MHz frequency range were acquired in 3 dimensions from all animals using each system. Each group processed their radio frequency data independently, and the resulting BSCs were compared. The rat tumors were diagnosed as either carcinoma or fibroadenoma. RESULTS: Carcinoma BSC results exhibited small variations between the multiple slices acquired with each transducer, with similar slopes of BSC versus frequency for all systems. Somewhat larger variations were observed in fibroadenomas, although BSC variations between slices of the same tumor were of comparable magnitude to variations between transducers and systems. The root mean squared (RMS) errors between different transducers and imaging platforms were highly variable. The lowest RMS errors were observed for the fibroadenomas between 4 and 5 MHz, with an average RMS error of 4 x 10(-5) cm(-1)Sr(-1) and an average BSC value of 7.1 x 10(-4) cm(-1)Sr(-1), or approximately 5% error. The highest errors were observed for the carcinoma between 7 and 8 MHz, with an RMS error of 1.1 x 10(-1) cm(-1)Sr(-1) and an average BSC value of 3.5 x 10(-2) cm(-1)Sr(-1), or approximately 300% error. CONCLUSIONS: This technical advance shows the potential for QUS technology to function with different imaging platforms.


Assuntos
Neoplasias/diagnóstico por imagem , Transdutores , Animais , Ratos , Ratos Sprague-Dawley , Ultrassonografia/instrumentação
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