Medical Engineering & Physics最新文献_第5页

Effect of plantar fascia stiffness on plantar windlass mechanism and arch: Finite element method and dual fluoroscopic imaging system verification 足底筋膜硬度对足底辘轳机制和足弓的影响：有限元法和双透视成像系统验证

IF 1.7 4区医学 Q3 ENGINEERING, BIOMEDICAL

Medical Engineering & Physics

Pub Date : 2024-11-19 DOI: 10.1016/j.medengphy.2024.104259

Qiaolin Zhang , Dong Sun , Meizi Wang , Viktória Tafferner-Gulyás , Hairong Chen , István Bíró , Yaodong Gu

This study explored the relationship between the foot arch stiffness and windlass mechanism, focusing on the contribution of the posterior transverse arch. Understanding the changing characteristics of foot stiffness is critical for providing a scientific basis for treating foot-related diseases. Based on a healthy male's computed tomography, kinematic, and dynamics data, a foot musculoskeletal finite element model with a dorsiflexion angle of 30°of metatarsophalangeal joint was established. Analyze the changes in stress distribution of the plantar fascia, metatarsophalangeal joint angle, arch height, and length during barefoot walking as the stiffness of the plantar fascia varies from 25 % to 200 %. For validation, the simulated arch parameters were compared with the dual fluorescence imaging system measurements. The width of transverse arch, height, and length of longitudinal arch measured by the dual fluorescence imaging system were 45.14 ± 1.63 mm, 29.29 ± 1.57 mm, and 155.16 ± 2.69 mm, respectively. The results of the simulation were 46.51 mm, 29.96 mm, and 156.71 mm, respectively. With the increase of plantar fascia stiffness, the effect of the windlass mechanism increased, the flexion angle of the metatarsophalangeal joint decreased, the distal stress of plantar fascia decreased gradually, while the proximal and middle stress increased, the transverse arch angle increased, but when the plantar fascia stiffness exceeds 150 %, the transverse arch angle decreases. The increase of plantar fascia stiffness will increase the effect of the windlass mechanism but decrease the flexion angle of the metatarsophalangeal joint. The stiffness of the plantar fascia influences the behavior of the plantar fascia. The plantar fascia stiffness affects the distal tension of the plantar fascia by affecting the flexion of the metatarsophalangeal joint in the plantar windlass mechanism. It affects the stiffness of the transverse arch of the foot together with the ground reaction force acting on the distal metatarsal.

本研究探讨了足弓硬度与辘轳机制之间的关系，重点关注后横弓的贡献。了解足部僵硬度的变化特征对于为治疗足部相关疾病提供科学依据至关重要。根据健康男性的计算机断层扫描、运动学和动力学数据，建立了跖趾关节背屈角度为 30°的足部肌肉骨骼有限元模型。分析赤足行走时，足底筋膜应力分布、跖趾关节角度、足弓高度和长度在足底筋膜硬度从 25% 到 200% 变化时的变化。为了进行验证，模拟的足弓参数与双荧光成像系统的测量结果进行了比较。双荧光成像系统测量的横向足弓宽度、高度和纵向足弓长度分别为 45.14 ± 1.63 毫米、29.29 ± 1.57 毫米和 155.16 ± 2.69 毫米。模拟结果分别为 46.51 毫米、29.96 毫米和 156.71 毫米。随着足底筋膜刚度的增加，辘轳机制的作用增大，跖趾关节屈曲角减小，足底筋膜远端应力逐渐减小，而近端和中部应力增大，横弓角增大，但当足底筋膜刚度超过 150 % 时，横弓角减小。足底筋膜硬度的增加会增加辘轳机制的作用，但会减小跖趾关节的屈曲角。足底筋膜的硬度影响足底筋膜的行为。足底筋膜硬度通过影响足底辘轳机制中跖趾关节的屈曲来影响足底筋膜的远端张力。它与作用在跖骨远端上的地面反作用力一起影响足部横弓的硬度。

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引用次数: 0

The effect of the length of chimney's protrusion on the hemodynamics of abdominal aorta stent graft after endovascular aneurysm repair 血管内动脉瘤修补术后烟囱突出长度对腹主动脉支架移植血液动力学的影响

IF 1.7 4区医学 Q3 ENGINEERING, BIOMEDICAL

Medical Engineering & Physics

Pub Date : 2024-11-19 DOI: 10.1016/j.medengphy.2024.104256

Moshe Brand , Hila Ben-Gur , Moshe Halak

Introduction

Abdominal aortic aneurysms present a significant clinical challenge, particularly when located near the renal arteries. In cases of infra-renal abdominal aortic aneurysms, the main stent graft may occlude the renal arteries, disrupting blood supply. To prevent this, two 'chimney' stent grafts can be implanted to maintain renal artery perfusion.

Method

This study investigates the impact of chimney stent graft protrusion length on the hemodynamics of stent graft using computational fluid dynamics (CFD). Two chimney configurations were analyzed, with the chimney protruding 10 and 30 mm above the upper part of the main stent graft. Key hemodynamic parameters were compared, including wall shear stress, blood flow velocity, and pathlines.

Results

The CFD analysis showed no substantial differences in hemodynamic parameters between these configurations.

Conclusions

The findings indicate negligible hemodynamic differences between the two chimney configurations. A chimney that protrudes 30 mm above the main stent graft is a viable option and may help reduce procedure time and patient risk.

导言腹主动脉瘤是一项重大的临床挑战，尤其是位于肾动脉附近的腹主动脉瘤。在肾下腹主动脉瘤的病例中，主支架移植物可能会堵塞肾动脉，破坏血液供应。本研究利用计算流体动力学（CFD）研究了烟囱支架移植物突出长度对支架移植物血液动力学的影响。研究分析了两种烟囱配置，烟囱分别突出主支架移植物上部 10 毫米和 30 毫米。结果 CFD 分析表明这两种配置的血液动力学参数没有实质性差异。在主支架移植物上方突出 30 毫米的烟囱是一种可行的选择，有助于减少手术时间和患者风险。

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引用次数: 0

Thermal simulation of the lower limb in vascular medicine: A proof-of-concept by using computed tomography images 血管医学中的下肢热模拟：使用计算机断层扫描图像进行概念验证

IF 1.7 4区医学 Q3 ENGINEERING, BIOMEDICAL

Medical Engineering & Physics

Pub Date : 2024-11-19 DOI: 10.1016/j.medengphy.2024.104260

Tomppa Pakarinen , Eko Hakala , Otso Arponen , Emppu Kuokkanen , Niku Oksala , Antti Vehkaoja

Simulations of physiology based on patient-specific anatomical structures have several potential applications in medicine. A few fields, such as radiotherapy and neurophysiology already utilize such methods in clinical practice, yet a number of disciplines could benefit from similar technologies, especially when imaging data is already available. The major problem in patient-specific simulation is the data conversion to simulation-compatible form i.e., data preparation and the coupling of the underlying physics to the anatomical model. In this work we present such a methodology in the context of vascular medicine, consisting of a three-dimensional blood flow-temperature simulation model of the lower limb built from computed tomography data. We also simulate a clinical condition of chronic limb-threatening ischemia, a severe complication of peripheral arterial disease. This proof-of-concept model simulates the limb's surface temperature with respect to the vascular structure. The methodology, depicting accurate patient anatomy, is a promising step towards individualized physiological simulations in vascular medicine, although more research and validation are required. Such a model could eventually outline a deeper understanding of the relation between vascular changes and peripheral thermal behavior.

基于病人特定解剖结构的生理学模拟在医学领域有多种潜在应用。放射治疗和神经生理学等少数领域已经在临床实践中使用了这种方法，但许多学科也可以从类似技术中获益，尤其是在已有成像数据的情况下。患者特异性模拟的主要问题是将数据转换为与模拟兼容的形式，即数据准备以及将基础物理学与解剖模型耦合。在这项工作中，我们以血管医学为背景提出了这样一种方法，它包括一个根据计算机断层扫描数据建立的下肢三维血流-温度模拟模型。我们还模拟了慢性肢体缺血的临床症状，这是外周动脉疾病的一种严重并发症。这个概念验证模型模拟了肢体表面温度与血管结构的关系。该方法描绘了准确的病人解剖结构，是血管医学向个性化生理模拟迈出的有希望的一步，但还需要更多的研究和验证。这种模型最终可以勾勒出对血管变化与外周热行为之间关系的更深入理解。

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引用次数: 0

Open laminectomy plus posterolateral fusion versus open laminectomy plus transforaminal lumbar interbody fusion surgical approaches for fusing degenerated L4-L5 segment: A comparative finite element study 开放式椎板切除术加后外侧融合术与开放式椎板切除术加经椎间孔腰椎椎体间融合术融合退化的 L4-L5 节段的手术方法：有限元比较研究

IF 1.7 4区医学 Q3 ENGINEERING, BIOMEDICAL

Medical Engineering & Physics

Pub Date : 2024-11-19 DOI: 10.1016/j.medengphy.2024.104261

Kishore Pradeep, Bidyut Pal

Various finite element (FE) studies reported the biomechanical effects of fusion surgeries in the lumbar spine. However, a comparative study on Open laminectomy plus Posterolateral Fusion (OL-PLF) and Open Laminectomy plus Transforaminal Lumbar Interbody Fusion (OL-TLIF) for fusing an L4-L5 segment has not been reported in the literature. The present comparative FE study evaluates the biomechanical variations in an L4-L5 segment fused using OL-PLF and OL-TLIF surgical approaches. The three-dimensional implanted models were constructed from a computed-tomography scan dataset using image processing software. The models were simulated for the physiological movements such as lateral bending, flexion and extension. The OL-TLIF model had a considerably larger peak equivalent strain than the OL-PLF model under extension (126 %), lateral bending (88 %) and flexion (13 %). However, in both implanted models, a peak equivalent strain above the compressive yield strain limit of the vertebra (0.007) was observed over 60 % of the L4-L5 fused segment, indicating an imminent post-operative bone failure under the imposed loading conditions. The maximum equivalent strain observed in the disc and endplates of the L3-L4 segment was substantially larger to initiate the adjacent segment degeneration. No discernible biomechanical benefits were observed for the OL-TLIF or OL-PLF approaches in fusing the L4-L5 segment.

多项有限元（FE）研究报告了腰椎融合手术的生物力学效应。然而，关于开放式椎板切除术加后侧融合术（OL-PLF）和开放式椎板切除术加经椎间孔腰椎椎体融合术（OL-TLIF）融合 L4-L5 节段的比较研究尚未见文献报道。本 FE 对比研究评估了采用 OL-PLF 和 OL-TLIF 手术方法融合 L4-L5 节段的生物力学变化。三维植入模型是利用图像处理软件从计算机断层扫描数据集中构建的。模型模拟了侧弯、屈曲和伸展等生理运动。在伸展（126%）、侧弯（88%）和屈曲（13%）时，OL-TLIF 模型的峰值等效应变比 OL-PLF 模型大得多。然而，在这两种植入模型中，L4-L5 融合节段的 60% 都出现了超过椎体压缩屈服应变极限（0.007）的峰值等效应变，这表明在施加的加载条件下，术后骨质即将发生破坏。在 L3-L4 节段的椎间盘和终板中观察到的最大等效应变远远大于邻近节段的退化。在融合 L4-L5 节段时，OL-TLIF 或 OL-PLF 方法没有观察到明显的生物力学优势。

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引用次数: 0

An in vitro experimental study on the synergistic pathogenicity analysis of pulsatile tinnitus involving venous flow velocity, sigmoid sinus wall dehiscence and sinus malformation 静脉流速、乙状窦壁开裂和窦畸形对搏动性耳鸣协同致病性分析的体外实验研究

IF 1.7 4区医学 Q3 ENGINEERING, BIOMEDICAL

Medical Engineering & Physics

Pub Date : 2024-11-19 DOI: 10.1016/j.medengphy.2024.104257

Shan Tian , Lanyue Chen , Chao Huang , Zhaohui Liu , Lizhen Wang , Yubo Fan

Pulsatile tinnitus (PT) is synchronous with patients’ heartbeat, with various reported intracranial etiologies. Sigmoid sinus wall dehiscence (SSWD), sinus malformation and high venous flow velocity were common marks of PT and were generally treated as independent etiology in clinic, but their coupling effect remains unclear. This study aimed to investigate the synergistic pathogenicity of these etiologies. The generation and propagation of venous sound was simulated by in vitro experiment. The entity models of sinus vessel, sinus wall and temporal bone cavity were 3D-printed using resin based on CT imaging. Pulsatile venous flow was generated through sinus lumen, with five velocity levels. Venous sound was collected and analyzed. It was found that pressure and pulsation of venous sound were determined by the coupling of three etiology conditions. Low velocity would not induce pulsatile sound anyway. Sub-high or higher velocity induced mild pulsatile sound coupling with normal sinus and wall. Medium or higher velocity induced moderate pulsatile sound coupling with SSWD and normal sinus. Sub-low or higher velocity induced moderate or severe pulsatile sound coupling with SSWD and sinus malformation. In conclusion, PT diagnosis should include the three investigated etiologies due to their contribution to amplifying venous sound. Among the three etiologies, SSWD exhibits the highest pathogenicity, while high venous flow velocity may reduce the effectiveness of SS wall reconstruction, and sinus malformation may exacerbate the intensity of tinnitus induced by SSWD.

搏动性耳鸣（PT）与患者的心跳同步，有多种颅内病因报道。乙状窦壁开裂（SSWD）、窦畸形和静脉流速过高是 PT 的常见标志，临床上通常将其作为独立病因处理，但其耦合效应仍不明确。本研究旨在探讨这些病因的协同致病性。通过体外实验模拟了静脉声的产生和传播。根据 CT 成像，用树脂三维打印了窦血管、窦壁和颞骨腔的实体模型。窦腔内产生了五级速度的脉动静脉流。收集并分析静脉声。结果发现，静脉声的压力和搏动是由三种病因条件耦合决定的。低速度无论如何都不会引起搏动性声音。次高速度或更高速度会引起与正常静脉窦和静脉壁耦合的轻微搏动声。中等或更高的速度会引起与 SSWD 和正常窦的中度搏动声耦合。次低或更高的速度引起中度或严重的搏动声耦合，伴有 SSWD 和窦畸形。总之，PT 诊断应包括所研究的三种病因，因为它们都有助于放大静脉声。在这三种病因中，SSWD 的致病性最高，而静脉流速过高可能会降低 SS 壁重建的效果，窦畸形可能会加重 SSWD 引起的耳鸣强度。

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引用次数: 0

Cadaveric validation of markerless tracking using weightbearing computed tomography versus conventional computed tomography imaging techniques 使用负重计算机断层扫描与传统计算机断层扫描成像技术进行无标记跟踪的尸体验证

IF 1.7 4区医学 Q3 ENGINEERING, BIOMEDICAL

Medical Engineering & Physics

Pub Date : 2024-11-12 DOI: 10.1016/j.medengphy.2024.104252

Katee N. Perez , Andrew C. Peterson , Rich J. Lisonbee , J.Peter Loan , Amy L. Lenz

This study aimed to validate the use of weightbearing computed tomography against conventional computed tomography and against bead tracking for markerless tracking of key foot and ankle bones. A left cadaveric limb was implanted with tantalum beads and underwent conventional computed tomography and weightbearing computed tomography scanning, followed by biplane fluoroscopy motion capture to simulate gait. Bone models from conventional computed tomography and weightbearing computed tomography were compared for surface differences and kinematic analysis across six joints. Results showed the average surface distance difference across all weightbearing computed tomography bones were a fraction of a voxel smaller than the conventional computed tomography bones on average. Additionally, the absolute mean and standard deviation of the mean angle differences across all trials, joints, and planes was less than one degree. Weightbearing computed tomography demonstrated comparable accuracy to conventional computed tomography and to bead tracking, confirming its utility in dynamic biomechanical analysis with reduced radiation exposure and the ability to image under load. This validation supports weightbearing computed tomography's broader adoption in clinical and research settings for enhanced foot and ankle diagnostics and treatment.

本研究旨在验证使用负重计算机断层扫描与传统计算机断层扫描以及无标记跟踪关键足部和踝部骨骼的磁珠跟踪之间的差异。在左侧尸体肢体上植入钽珠，进行传统计算机断层扫描和负重计算机断层扫描，然后进行双平面透视运动捕捉以模拟步态。比较了传统计算机断层扫描和负重计算机断层扫描的骨模型表面差异和六个关节的运动学分析。结果显示，所有负重计算机断层扫描骨骼的平均表面距离差异比传统计算机断层扫描骨骼平均小几分之一体素。此外，所有试验、关节和平面的平均角度差的绝对平均值和标准偏差均小于一度。负重计算机断层扫描的精确度与传统计算机断层扫描和磁珠跟踪相当，证实了其在动态生物力学分析中的实用性，同时减少了辐射暴露，并能在负荷下成像。这一验证支持了负重计算机断层扫描技术在临床和研究领域的广泛应用，以提高足踝诊断和治疗的效果。

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引用次数: 0

A compact and cost-effective gait simulator to advance prosthesis development with reduced reliance on human subject testing: Development, validation and application 结构紧凑、成本效益高的步态模拟器，可减少对人体测试的依赖，推动假肢开发：开发、验证和应用

IF 1.7 4区医学 Q3 ENGINEERING, BIOMEDICAL

Medical Engineering & Physics

Pub Date : 2024-11-07 DOI: 10.1016/j.medengphy.2024.104254

S. Sudeesh, M.S. Shunmugam, S. Sujatha

Gait simulators play a crucial role in assessing the performance of physical prototypes of prosthetic knees, validating numerical simulation findings, and reducing dependency on user trials during prosthesis development. However, their practical application is limited because of substantial capital investment required for sophisticated high degrees-of-freedom (DOF) system development on one side and insufficient DOF for accurate simulation on the other. In this study, we evaluated the minimum DOF of thigh segment that a gait simulator should have to test the performance of prosthetic knees in a cost-effective manner. Initially, numerical simulations of swing phase of prosthetic leg with IITM polycentric knee (IPK) using 3D gait data and with different arrested DOF of the thigh were performed to identify the essential DOF of gait simulator. By comparing different cases of arrested DOF with the six-DOF ideal case, it was revealed that only sagittal plane movements, namely flexion-extension, vertical translation, and horizontal translation, are sufficient to test prosthetic knees. Subsequently, a compact and modular gait simulator was developed. Hardware-in-loop simulations of the IPK using the gait simulator were used to demonstrate its effectiveness in assessing the performance of prosthetic knees, which validated the ability of the IPK to extend completely without an extension assist before heel contact. Additionally, it was exposed that the IPK's extension stop needs redesigning to effectively absorb the impact energy when the knee extends completely before heel contact. These findings emphasize the significance of a cost-effective gait simulator in prosthesis development and reduce dependency on user trials.

步态模拟器在评估假肢膝关节物理原型的性能、验证数值模拟结果以及减少假肢开发过程中对用户试验的依赖方面发挥着至关重要的作用。然而，由于一方面复杂的高自由度（DOF）系统开发需要大量资金投入，另一方面用于精确模拟的 DOF 不足，因此其实际应用受到了限制。在这项研究中，我们评估了步态模拟器应具备的大腿部分最小 DOF，以便以经济有效的方式测试假肢膝关节的性能。起初，我们使用三维步态数据和不同的大腿阻尼DOF，对假肢与IITM多中心膝（IPK）的摆动阶段进行了数值模拟，以确定步态模拟器的基本DOF。通过将不同的阻滞 DOF 与六 DOF 理想情况进行比较，发现只有矢状面运动，即屈伸、垂直平移和水平平移，才足以测试假肢膝关节。随后，我们开发了一种紧凑型模块化步态模拟器。使用步态模拟器对IPK进行了硬件在环模拟，以证明其在评估义肢膝关节性能方面的有效性，验证了IPK在脚跟接触前完全伸展而无需伸展辅助的能力。此外，IPK的伸展止挡需要重新设计，以便在膝关节在脚跟接触前完全伸展时有效吸收冲击能量。这些发现强调了具有成本效益的步态模拟器在假肢开发中的重要性，并减少了对用户试验的依赖。

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引用次数: 0

3D bioheat transfer mapping reveals nanomagnetic particles effectiveness in radiofrequency hyperthermia breast cancer treatment comparing to experimental study 与实验研究相比，三维生物传热图揭示了纳米磁性微粒在射频热疗乳腺癌治疗中的有效性

IF 1.7 4区医学 Q3 ENGINEERING, BIOMEDICAL

Medical Engineering & Physics

Pub Date : 2024-11-01 DOI: 10.1016/j.medengphy.2024.104249

Mahsa Kavousi , Erfan Saadatmand , Mahboubeh Masoumbeigi , Rabi Mahdavi , Nader Riyahi Alam

Radiofrequency (RF) hyperthermia has been widely used for tumor ablation since magnetic-fluid-hyperthermia (MFH) can be utilized for increasing temperature in tumor-region as a complementary-method for hyperthermia. In this study, the effectiveness of using the magnetite-nanoparticles (Fe₃O₄) in RF hyperthermia for breast cancer (BC) treatment by determining 3D-temperature-distribution using bioheat-transfer-mapping was evaluated. A breast-phantom with a tumor region was placed in an RF-device with 13.56 MHz frequency in different states (with and without-nanomagnetite). Parallelly, the calculations of the RF-wave and bioheat-equation were accomplished by numerical-simulation and finite-element-method (FEM) in COMSOL-software. The temperature differences were experimentally measured at different points of the phantom with a precision of 0.1 °C, with temperature of 3.6 °C and 6.1 °C in without and with nanomagnetic conditions in tumor area, respectively, and also for normal area with temperature of 1.8 °C and 1.9 °C in non-presence and presence states of 0.05 gr magnetite for both conditions, respectively. Moreover, the difference between the simulation and the experimental results was 0.54–1.1 %. The conformity between temperature measurement in experimental and simulation studies in tumor and normal areas showed the effectiveness of the application of MNPs for RF hyperthermia in tissue equivalent breast phantom. Finally, the positive effect of 0.05 gr of MNPs on BC treatment was confirmed.

射频（RF）热疗已被广泛用于肿瘤消融，因为磁流体热疗（MFH）可作为热疗的补充方法用于提高肿瘤区域的温度。在这项研究中，通过使用生物热传递图确定三维温度分布，评估了在射频热疗中使用磁铁矿纳米颗粒（Fe3O4）治疗乳腺癌（BC）的有效性。在不同状态下（含纳米磁铁矿和不含纳米磁铁矿），将带有肿瘤区域的乳房假体置于频率为 13.56 MHz 的射频设备中。同时，通过 COMSOL 软件中的数值模拟和有限元法（FEM）完成了射频波和生物热方程的计算。通过实验测量了模型不同点的温差，精度为 0.1 °C，肿瘤区域在无纳米磁性和有纳米磁性条件下的温度分别为 3.6 °C和 6.1 °C，正常区域在无和有 0.05 gr 磁铁矿条件下的温度分别为 1.8 °C和 1.9 °C。此外，模拟结果与实验结果的差异为 0.54-1.1%。在肿瘤和正常区域进行的实验和模拟研究的温度测量结果一致，这表明在组织等效的乳房模型中应用 MNPs 进行射频热疗是有效的。最后，0.05 克 MNPs 对 BC 治疗的积极作用得到了证实。

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引用次数: 0

Monitoring focused ultrasound ablation surgery (FUAS) using echo amplitudes of the therapeutic focused transducer 利用治疗性聚焦换能器的回声振幅监测聚焦超声消融手术（FUAS）

IF 1.7 4区医学 Q3 ENGINEERING, BIOMEDICAL

Medical Engineering & Physics

Pub Date : 2024-11-01 DOI: 10.1016/j.medengphy.2024.104247

Yufeng Zhou , Xiaobo Gong , Yaqin You

Objective

B-mode sonography is commonly used to monitor focused ultrasound ablation surgery (FUAS), but has limitations in sensitivity. More accurate and reliable prediction of coagulation is required.

Methods

The focused ultrasound (FUS) transducer was adapted for echo reception. Numerical simulations compared the normalized echo amplitudes from the FUS transducer and imaging probe at varying tissue depths and frequencies with a 3 mm necrosis at focus. An ex vivo experiment then evaluated echo changes from the FUS transducer and ultrasound imaging probe under different settings. Finally, coagulation prediction using FUS echo data was compared to sonography in a clinical ex vivo context.

Results

The echo amplitudes from the FUS transducer exhibit a less pronounced decline with increasing tissue penetration depth compared to the ultrasound imaging probe. In ex vivo bovine liver experiments at depths of 2 cm and 4 cm, the FUS transducer detected normalized echo amplitudes that were significantly larger (i.e., 2∼3 folds) than those received by the ultrasound imaging probe. Moreover, multi-layered ex vivo tissue experiments that replicate clinical conditions revealed that coagulation prediction utilizing the FUS transducer's echo amplitudes achieved superior accuracy (91.2% vs. 60.3 %), sensitivity (92.1% vs. 54.5 %), and negative prediction (78.9% vs. 30.6 %), but similar specificity (88.2% vs. 84.6 %) and positive prediction (95.9% vs. 93.8 %) in comparison to sonography.

Conclusion

The echo amplitude of the FUS transducer serves as a sensitive and dependable metric for monitoring the FUAS outcomes. Its utilization may augment the procedure's safety and efficacy.

目的B型超声造影通常用于监测聚焦超声消融手术（FUAS），但在灵敏度方面存在局限性。方法对聚焦超声（FUS）换能器进行改装，使其能够接收回波。数值模拟比较了 FUS 换能器和成像探头在不同组织深度和频率下的归一化回波振幅，病灶处有 3 毫米坏死。然后进行了一次体内实验，评估了不同设置下 FUS 传感器和超声成像探头的回声变化。结果与超声成像探头相比，随着组织穿透深度的增加，FUS 换能器产生的回声振幅下降不那么明显。在深度为 2 厘米和 4 厘米的体外牛肝实验中，FUS 传感器检测到的归一化回波振幅明显大于超声成像探头接收到的回波振幅（即 2∼3 倍）。此外，复制临床条件的多层体外组织实验显示，利用 FUS 传感器的回波振幅进行凝血预测的准确性（91.2% 对 60.3%）、灵敏度（92.1% 对 54.5%）和阴性预测（78.结论 FUS 传感器的回声振幅是监测 FUAS 结果的灵敏可靠的指标。利用它可以提高手术的安全性和有效性。

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引用次数: 0

Evaluation of a finite state machine algorithm to measure stepping with ankle accelerometry: Performance across a range of gait speeds, tasks, and individual walking ability 评估利用脚踝加速度计测量步速的有限状态机算法：不同步速、任务和个人行走能力下的性能表现

IF 1.7 4区医学 Q3 ENGINEERING, BIOMEDICAL

Medical Engineering & Physics

Pub Date : 2024-11-01 DOI: 10.1016/j.medengphy.2024.104251

Benjamin F Cornish , Karen Van Ooteghem , Matthew Wong , Kyle S Weber , Frederico Pieruccini-Faria , Manuel Montero-Odasso , William E McIlroy

Wearable sensors, including accelerometers, are a widely accepted tool to assess gait in clinical and free-living environments. Methods to identify phases and subphases of the gait cycle are necessary for comprehensive assessment of pathological gait. The current study evaluated the accuracy of a finite state machine (FSM) algorithm to detect strides by identifying gait cycle subphases from ankle-worn accelerometry. Algorithm performance was challenged across a range of speeds (0.4-2.6 m/s), task conditions (e.g., single- and dual-task walking), and individual characteristics. Specifically, the study included a range of treadmill speeds in young adults and overground walking conditions in older adults with neurological disease. Manually counted and algorithm-derived stride detection from acceleration data were evaluated using error analysis and Bland-Altman plots for visualization. Overall, the algorithm successfully detected strides (>96 % accuracy) across gait speed ranges and tasks, for young and older adults. The accuracy of an FSM algorithm combined with ankle-worn accelerometers, provides an analytical approach with affordable and portable tools that permits comprehensive assessment of gait unbounded by setting and proves to perform well in in walking tasks characterized by variable walking. These algorithm capabilities and advancements are critical for identifying phase dependent gait impairments in clinical and free-living assessment.

在临床和自由生活环境中，包括加速度计在内的可穿戴传感器是一种广为接受的步态评估工具。识别步态周期的阶段和子阶段的方法是全面评估病态步态所必需的。目前的研究评估了有限状态机（FSM）算法的准确性，该算法通过识别踝戴式加速度计的步态周期子阶段来检测步幅。该算法的性能在一系列速度（0.4-2.6 米/秒）、任务条件（如单任务和双任务步行）和个体特征中受到了挑战。具体来说，研究包括年轻成年人的一系列跑步机速度和患有神经系统疾病的老年人的地面行走条件。使用误差分析和布兰-阿尔特曼图对加速度数据中手动计数和算法衍生的步幅检测进行了评估。总体而言，该算法在不同步速范围和任务中成功检测到了年轻人和老年人的步幅（准确率达 96%）。FSM 算法的准确性与踝戴式加速度计相结合，提供了一种分析方法，它具有经济实惠、便于携带的工具，可以不受环境限制地对步态进行全面评估，并证明在以步态多变为特征的步行任务中表现良好。这些算法的功能和进步对于在临床和自由生活评估中识别相位依赖步态障碍至关重要。

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