Biomechanics and imaging

From the perspective of biomechanics, my research is multidisciplinary, bridging the gap between physiology/biology and quantitative sciences. Currently, the applications are on cancer detection and differentiation, therapeutic monitoring, staging liver fibrosis, risk assessment of aneurysm rupture, and more.https://digitalcommons.mtu.edu/techtalks/1035/thumbnail.jp

Role of transient receptor potential vanilloid subetype 1 in the increase of thermal pain threshold by moxibustion

AbstractObjectiveTo explore the role of transient receptor potential vanilloid subetype 1 (TRPV1) in the increase of the thermal pain threshold by moxibustion.MethodsForty Kunming mice (20 ± 2) g were randomized into control group, capsaicin group, capsazepine group, moxibustion group and moxibustion + capsazepine (MC) group with 8 mice in each, and 16 C57BL/6 wild-type mice (18 ± 2) g were randomized into wild-type (WT) control group and WT moxibustion group with 8 mice in each, and 14 TRPV1 knockout mice (18 ± 2) g were randomized into knockout (KO) control group and KO moxibustion group with 7 in each. Each mouse in the capsaicin group was subcutaneously injected with the amount of 0.1 mL/10 g into L5 and L6 spinal cords; each mouse in the capsazepine group was intraperitoneally injected with the amount of 0.1 mL/10 g. Similarly, each mouse in the moxibustion group was given a suspended moxibustion with specially-made moxa-stick for 20 min on L5 and L6 spinal cords. Each mouse in MC group was intraperitoneally injected with the amount of 0.1 mL/10 g first, then after 15 min was given a suspended moxibustion for 20 min on L5 and L6 spinal cords. Each mouse in WT moxibustion group and KO moxibustion group was given a suspended moxibustion with specially-made moxa-stick for 20 min on L5 and L6 spinal cords. The control group, WT control group and KO control group were of no treatment in any way. After all treatments were completed, the digital-display measurement instrument for thermal pain was used to measure the threshold of thermal pain in each group respectively.ResultsCompared with the control group, the thresholds of thermal pain in the moxibustion group and MC group were significantly increased (P <0.01); no significant changes in the thresholds in the capsaicin group and the capsazepine group (P > 0.05); compared with moxibustion group, he threshold of thermal in MC group was obviously decreased (P < 0.01). Compared with WT control group, the threshold of thermal pain in WT moxibustion group was significantly increased (P < 0.01); compared with KO control group, no changes in the threshold in KO moxibustion group (P > 0.05).ConclusionTRPV1 participated in the process of increasing the threshold of thermal pain by stimulating L5 and L6 of mice spinal cord with burning mosa-stick

A Normalized Shear Deformation Indicator for Ultrasound Strain Elastography in Breast Tissues: An In Vivo

The shear deformation under loads contains useful information for distinguishing benign breast lesions from malignant ones. In this study, we proposed a normalized shear deformation indicator (NSDI) that was derived from the concept of principal strains. Since the NSDI requires both high-quality axial and lateral (parallel and perpendicular to the beam, resp.) displacement estimates, a strategy combining high-quality speckle tracking with signal “denoising” was employed. Both techniques were previously published by our group. Finite element (FE) models were used to identify possible causes for elevated NSDI values in and around breast lesions, followed by an analysis of ultrasound data acquired from 26 biopsy-confirmed in vivo breast lesions. We found that, theoretically, the elevated NSDI values could be attributed to two factors: significantly hardened tissue stiffness and increasing heterogeneity. The analysis of in vivo data showed that the proposed NSDI values were higher (p<0.05) among malignant cancers as compared to those measured from benign ones. In conclusion, our preliminary results demonstrated that the calculation of NSDI value is feasible and NSDI could add value to breast lesion differentiation with current clinical equipment as a postprocessing tool

A comparison of hyperelastic constitutive models applicable to shear wave elastography (SWE) data in tissue-mimicking materials

Shear wave elastography (SWE) techniques have received substantial attention in recent years. Strong experimental data in SWE suggest that shear wave speed changes significantly due to the known acoustoelastic effect (AE). This presents both challenges and opportunities toward in vivo characterization of biological soft tissues. In this work, under the framework of continuum mechanics, we model a tissue-mimicking material as a homogeneous, isotropic, incompressible, hyperelastic material. Our primary objective is to quantitatively and qualitatively compare experimentally measured acoustoelastic data with model-predicted outcomes using multiple strain energy functions. Our analysis indicated that the classic neo-Hookean and Mooney-Rivlin models are inadequate for modeling the AE in tissue-mimicking materials. However, a subclass of strain energy functions containing both high-order /exponential term(s) and second-order invariant dependence showed good agreement with experimental data. Based on data investigated, we also found that discrepancies may exist between parameters inversely estimated from uniaxial compression and SWE data. Overall, our findings may improve our understanding of clinical SWE results

Accelerating 3-D GPU-based Motion Tracking for Ultrasound Strain Elastography Using Sum-Tables: Analysis and Initial Results.

Now, with the availability of 3-D ultrasound data, a lot of research efforts are being devoted to developing 3-D ultrasound strain elastography (USE) systems. Because 3-D motion tracking, a core component in any 3-D USE system, is computationally intensive, a lot of efforts are under way to accelerate 3-D motion tracking. In the literature, the concept of Sum-Table has been used in a serial computing environment to reduce the burden of computing signal correlation, which is the single most computationally intensive component in 3-D motion tracking. In this study, parallel programming using graphics processing units (GPU) is used in conjunction with the concept of Sum-Table to improve the computational efficiency of 3-D motion tracking. To our knowledge, sum-tables have not been used in a GPU environment for 3-D motion tracking. Our main objective here is to investigate the feasibility of using sum-table-based normalized correlation coefficient (ST-NCC) method for the above-mentioned GPU-accelerated 3-D USE. More specifically, two different implementations of ST-NCC methods proposed by Lewis et al. and Luo-Konofagou are compared against each other. During the performance comparison, the conventional method for calculating the normalized correlation coefficient (NCC) was used as the baseline. All three methods were implemented using compute unified device architecture (CUDA; Version 9.0, Nvidia Inc., CA, USA) and tested on a professional GeForce GTX TITAN X card (Nvidia Inc., CA, USA). Using 3-D ultrasound data acquired during a tissue-mimicking phantom experiment, both displacement tracking accuracy and computational efficiency were evaluated for the above-mentioned three different methods. Based on data investigated, we found that under the GPU platform, Lou-Konofaguo method can still improve the computational efficiency (17-46%), as compared to the classic NCC method implemented into the same GPU platform. However, the Lewis method does not improve the computational efficiency in some configuration or improves the computational efficiency at a lower rate (7-23%) under the GPU parallel computing environment. Comparable displacement tracking accuracy was obtained by both methods

Topologically protected subradiant cavity polaritons through linewidth narrowing enabled by dissipationless edge states

Cavity polaritons derived from the strong light-matter interaction at the quantum level provide a basis for efficient manipulation of quantum states via cavity field. Polaritons with narrow linewidth and long lifetime are appealing in applications such as quantum sensing and storage. Here, we propose a prototypical arrangement to implement a whispering-gallery-mode resonator with topological mirror moulded by one-dimensional atom array, which allows to boost the lifetime of cavity polaritons over an order of magnitude. This considerable enhancement attributes to the coupling of polaritonic states to dissipationless edge states protected by the topological bandgap of atom array that suppresses the leakage of cavity modes. When exceeding the width of Rabi splitting, topological bandgap can further reduce the dissipation from polaritonic states to bulk states of atom array, giving arise to subradiant cavity polaritons with extremely sharp linewidth. The resultant Rabi oscillation decays with a rate even below the free-space decay of a single quantum emitter. Inheriting from the topologically protected properties of edge states, the subradiance of cavity polaritons can be preserved in the disordered atom mirror with moderate perturbations involving the atomic frequency, interaction strengths and location. Our work opens up a new paradigm of topology-engineered quantum states with robust quantum coherence for future applications in quantum computing and network.Comment: 19 pages,8 figure

An attention residual u-net with differential preprocessing and geometric postprocessing: Learning how to segment vasculature including intracranial aneurysms

Objective Intracranial aneurysms (IA) are lethal, with high morbidity and mortality rates. Reliable, rapid, and accurate segmentation of IAs and their adjacent vasculature from medical imaging data is important to improve the clinical management of patients with IAs. However, due to the blurred boundaries and complex structure of IAs and overlapping with brain tissue or other cerebral arteries, image segmentation of IAs remains challenging. This study aimed to develop an attention residual U-Net (ARU-Net) architecture with differential preprocessing and geometric postprocessing for automatic segmentation of IAs and their adjacent arteries in conjunction with 3D rotational angiography (3DRA) images. Methods The proposed ARU-Net followed the classic U-Net framework with the following key enhancements. First, we preprocessed the 3DRA images based on boundary enhancement to capture more contour information and enhance the presence of small vessels. Second, we introduced the long skip connections of the attention gate at each layer of the fully convolutional decoder-encoder structure to emphasize the field of view (FOV) for IAs. Third, residual-based short skip connections were also embedded in each layer to implement in-depth supervision to help the network converge. Fourth, we devised a multiscale supervision strategy for independent prediction at different levels of the decoding path, integrating multiscale semantic information to facilitate the segmentation of small vessels. Fifth, the 3D conditional random field (3DCRF) and 3D connected component optimization (3DCCO) were exploited as postprocessing to optimize the segmentation results. Results Comprehensive experimental assessments validated the effectiveness of our ARU-Net. The proposed ARU-Net model achieved comparable or superior performance to the state-of-the-art methods through quantitative and qualitative evaluations. Notably, we found that ARU-Net improved the identification of arteries connecting to an IA, including small arteries that were hard to recognize by other methods. Consequently, IA geometries segmented by the proposed ARU-Net model yielded superior performance during subsequent computational hemodynamic studies (also known as patient-specific computational fluid dynamics [CFD] simulations). Furthermore, in an ablation study, the five key enhancements mentioned above were confirmed. Conclusions The proposed ARU-Net model can automatically segment the IAs in 3DRA images with relatively high accuracy and potentially has significant value for clinical computational hemodynamic analysis

High Glucose Induces Reactivation of Latent Kaposi’s Sarcoma-Associated Herpesvirus

High prevalence of Kaposi’s sarcoma (KS) is seen in diabetic patients. It is unknown if the physiological condition of diabetes contributes to KS development. We found elevated levels of viral lytic gene expression when Kaposi’s sarcoma-associated herpesvirus (KSHV) infected cells were cultured in high glucose medium. To demonstrate the association between high glucose and KSHV replication, we xeno29 grafted telomerase-immortalized human umbilical vein endothelial cells that are infected with KSHV (TIVE-KSHV) into hyperglycemic and normal nude mice. The injected cells expressed significantly higher levels of KSHV lytic genes in hyperglycemic mice than in normal mice. We further demonstrated that high glucose induced production of hydrogen peroxide (H2O2), which down regulated silent information regulator 1 (SIRT1), a class-III histone deacetylase (HDAC), resulting in epigenetic transactivation of KSHV lytic genes.These results suggest that high blood glucose in diabetic patients contributes to development of KS by promoting KSHV lytic replication and infection