Featured Articles

Knock-in of a Large Reporter Gene via the High-Throughput Microinjection of the CRISPR/Cas9 System

Knock-in of a Large Reporter Gene via the High-Throughput Microinjection of the CRISPR/Cas9 System 780 435 IEEE Transactions on Biomedical Engineering (TBME)
This work demonstrates the microinjection of CRISPR/Cas9 with an enhanced green fluorescent protein (GFP) donor template into single HepG2 cells can achieve reporter gene knock-in targeting the adeno-associated virus site 1 locus. Homology-directed repair-mediated knock-in can be observed with an efficiency of 41%. Assessment via T7E1 assay indicates that the GFP knock-in cells exhibit no detectable changes at potential off-target sites. A case study of injecting the GFP knock-in cells into zebrafish (Danio rerio) embryos to form an in vivo tumor model is conducted. Results demonstrate the efficiency of combining microinjection with the CRISPR/Cas9 system in achieving gene knock-in. read more

MRI-Guided Cardiac RF Ablation for Comparing MRI Characteristics of Acute Lesions and Associated Electrophysiologic Voltage Reductions

MRI-Guided Cardiac RF Ablation for Comparing MRI Characteristics of Acute Lesions and Associated Electrophysiologic Voltage Reductions 2560 1427 IEEE Transactions on Biomedical Engineering (TBME)
This study characterizes permanent and transient injury caused by cardiac RF ablation in a preclinical model. Native-contrast MRI features of ablation were investigated in relation to catheter-based electrophysiologic (EP) signals inherently co-registered within the same coordinate frame, and histologically validated. Specifically, we show that bipolar voltage was reduced in the presence of both the permanent T1-derived RF lesion and transient T2-derived edema. These results suggest that these regions are distinct in native-contrast MRI, but not differentiable using bipolar voltage. Intraprocedural MRI visualization distinguishing transient and permanent injury could guide creation of more complete durable RF ablations, reducing arrhythmia recurrence. read more

Quantification and 3D Localization of Magnetically Navigated Superparamagnetic Particles Using MRI in Phantom and Swine Chemoembolization Models

Quantification and 3D Localization of Magnetically Navigated Superparamagnetic Particles Using MRI in Phantom and Swine Chemoembolization Models 780 435 IEEE Transactions on Biomedical Engineering (TBME)

Author(s): Ning Li, Cyril Tous, Ivan P. Dimov, Dominic Cadoret, Phillip Fei, Yasamin Majedi, Simon Lessard, Zeynab Nosrati, Katayoun Saatchi, Urs O. Häfeli, An Tang, Samuel Kadoury, Sylvain Martel, Gilles…

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Estimating the neovascularity of human finger tendon through high-frequency ultrasound micro-Doppler imaging

Estimating the neovascularity of human finger tendon through high-frequency ultrasound micro-Doppler imaging 780 435 IEEE Transactions on Biomedical Engineering (TBME)
High-frequency micro-Doppler imaging (HFμDI) based on 40-MHz ultrafast ultrasound imaging was proposed for visualizing the neovascularization in injured finger tendons through block-wise singular value decomposition filtering and curvilinear structure enhancement. Small animal imaging experiments revealed that HFμDI provides excellent performance and the minimum vessel size was 35 μm without contrast agents. Neovascularization was clearly observed in injured finger tendons during the early phase of healing (weeks 11–21) and regressed from week 52-56. Neovascular density decreased by approximately 1.8%–8.0% after 4 weeks of rehabilitation. The experimental results indicate the potential of HFμDI for injured finger tendon evaluations. read more

Improving the Energy Cost of Incline Walking and Stair Ascent with Ankle Exoskeleton Assistance in Cerebral Palsy

Author(s): Ying Fang, Greg Orekhov, Zachary F. Lerner
Improving the Energy Cost of Incline Walking and Stair Ascent with Ankle Exoskeleton Assistance in Cerebral Palsy 150 150 IEEE Transactions on Biomedical Engineering (TBME)
Graded walking terrains pose significant mobility challenges for individuals with movement disorders, including those with cerebral palsy (CP). We tested the ability of a novel battery-powered ankle exoskeleton to improve stair, incline, and real-world mixed-terrain walking in seven individuals with CP. Adaptive ankle assistance improved the energy cost of steady-state incline walking by 14% and stair ascent by 21% compared to walking without the device. This is the first study to demonstrate safety and performance benefits of ankle exoskeleton assistance on graded terrains in CP, and it encourages future studies to evaluate assistance on mixed-terrain walking in free-living environments. read more

3D Acoustic Manipulation of Living Cells and Organisms Based on 2D Array

Author(s): Ye Yang, Teng Ma, Qi Zhang, Jiqing Huang, Yongchuan Li, Congzhi Wang, Hairong Zheng
3D Acoustic Manipulation of Living Cells and Organisms Based on 2D Array IEEE Transactions on Biomedical Engineering (TBME)
This work aims to realize programmable manipulation for living cells and micro-organisms in a common Petri dish by using holographic acoustic tweezers. Based on a self-developed 2D ultrasound matrix array, we successfully synthesize various complex acoustic fields and achieve the precise regulation of the fields both in space and time, and further build a holographic acoustic tweezer system compatible with microscopic imaging. This system innovatively realizes multidimensional translation, rotation, orientation, and levitation of living cells and micro-organisms, thereby demonstrating their value for advancing research in the fields of cell assembly, tissue engineering, and micro-robot driving. read more

Electroporation Microchip With Integrated Conducting Polymer Electrode Array for Highly Sensitive Impedance Measurement

Electroporation Microchip With Integrated Conducting Polymer Electrode Array for Highly Sensitive Impedance Measurement IEEE Transactions on Biomedical Engineering (TBME)
An in vitro platform is presented that monitors the degree of electroporation while cells are treated with pulsed electric fields. The developed electroporation chip can assess the integrity of a monolayer of cells by performing electrochemical impedance spectroscopy with microelectrodes. The sensitivity of the system is significantly enhanced by reducing the impedance of the sensing electrodes which is achieved by applying a PEDOT:PSS coating. The integrated system of sensing and stimulation electrodes provides feedback on treatment progression and can be used to study electroporation dynamics. read more

3D Transcranial Ultrasound Localization Microscopy in the Rat Brain with a Multiplexed Matrix Probe

3D Transcranial Ultrasound Localization Microscopy in the Rat Brain with a Multiplexed Matrix Probe IEEE Transactions on Biomedical Engineering (TBME)
Ultrasound Localization Microscopy (ULM) provides high-resolution imaging of the microcirculation in-depth in living tissue. Micrometric bubbles are injected into the bloodstream and localized individually to reconstruct the vascularization of an organ. This work presents an implementation of volumetric ULM with a multiplexed matrix probe driven by a single commercial ultrasound scanner. Multiple optimizations enabled acquiring up to 100,000 volumes at 250 Hz during 7 minutes for ULM imaging of the rat brain. After reconstruction, vessels are revealed down to 31 µm in diameter under the intact skull of the animal, with blood flows from 4.3 to 28.4 mm/s. read more

A handheld fiber-optic probe to enable optical coherence tomography of oral soft tissue

A handheld fiber-optic probe to enable optical coherence tomography of oral soft tissue IEEE Transactions on Biomedical Engineering (TBME)
This work presents a small, light-weight scanning probe for optical coherence tomography. We present an all-fiber optical design and integrate this with a magnetic scanning mechanism to create a probe the size of a pen (10mm x 140mm) and weighing only 10 grams. To demonstrate the high image quality, we performed imaging on the soft tissue in the mouths of six patients under-going examination for oral lichen planus. Our images show clear distinctions between normal and diseased tissue. read more