Precise aneurysm volume measurement offers a transformative edge for risk assessment and treatment planning in clinical settings. Currently, clinical assessments rely heavily on manual review of medical imaging, a process that is time-consuming and prone to inter-observer variability. The widely accepted standard-of-care primarily focuses on measuring aneurysm diameter at its widest point, providing a limited perspective on aneurysm morphology and lacking efficient methods to measure aneurysm volumes. Yet, volume measurement can offer deeper insight into aneurysm progression and severity. In this study, we propose an automated approach that leverages the strengths of pre-trained neural networks and expert systems to delineate aneurysm boundaries and compute volumes on an unannotated dataset from 60 patients. The dataset includes slice-level start/end annotations for aneurysm but no pixel-wise aorta segmentations. Our method utilizes a pre-trained UNet to automatically locate the aorta, employs SAM2 to track the aorta through vascular irregularities such as aneurysms down to the iliac bifurcation, and finally uses a Long Short-Term Memory (LSTM) network or expert system to identify the beginning and end points of the aneurysm within the aorta. Despite no manual aorta segmentation, our approach achieves promising accuracy, predicting the aneurysm start point with an R2 score of 71%, the end point with an R2 score of 76%, and the volume with an R2 score of 92%. This technique has the potential to facilitate large-scale aneurysm analysis and improve clinical decision-making by reducing dependence on annotated datasets.

Background/Objective: Precise aneurysm volume measurement offers a transformative edge for risk assessment and treatment planning in clinical settings. Currently, clinical assessments rely heavily on manual review of medical imaging, a process that is time-consuming and prone to inter-observer variability. The widely accepted standard of care primarily focuses on measuring aneurysm diameter at its widest point, providing a limited perspective on aneurysm morphology and lacking efficient methods to measure aneurysm volumes. Yet, volume measurement can offer deeper insight into aneurysm progression and severity. In this study, we propose an automated approach that leverages the strengths of pre-trained neural networks and expert systems to delineate aneurysm boundaries and compute volumes on an unannotated dataset from 60 patients. The dataset includes slice-level start/end annotations for aneurysm but no pixel-wise aorta segmentations. Method: Our method utilizes a pre-trained UNet to automatically locate the aorta, employs SAM2 to track the aorta through vascular irregularities such as aneurysms down to the iliac bifurcation, and finally uses a Long Short-Term Memory (LSTM) network or expert system to identify the beginning and end points of the aneurysm within the aorta. Results: Despite no manual aorta segmentation, our approach achieves promising accuracy, predicting the aneurysm start point with an R2 score of 71%, the end point with an R2 score of 76%, and the volume with an R2 score of 92%. Conclusions: This technique has the potential to facilitate large-scale aneurysm analysis and improve clinical decision-making by reducing dependence on annotated datasets.

Endothelial dysfunction, defined as a reduction in the bioavailability of nitric oxide (NO), is a risk factor for the occurrence and progression of various vascular diseases. This study investigates the effect of endothelial dysfunction on age-related changes in aortic extracellular matrix (ECM) microstructure and the relationship between microstructural adaptation and the mechanical response. Here, we used groups of NOS3 knockout (KO), NOS3 heterozygotes (Het), and wild-type (WT) B6 mice (controls) to study changes in hemodynamic parameters, collagen fiber organization, and both active and passive aortic mechanics using biaxial pressure myography over a time course from 1.5 to 12 mo. Our results show that homeostatic levels of passive circumferential stress and stretch were preserved in KO mice by remodeling adventitial collagen fibers toward a more predominantly circumferential direction with age, rather than by increased fibrosis, in response to hypertension induced by endothelial dysfunction. However, passive aortic stiffness in KO mice was significantly increased owing to geometrical changes, including significant increases in wall thickness and decreases in inner diameter, and by ECM microstructural reorganization, during this maladaptive vascular remodeling. Furthermore, long-term NO deficiency significantly increased smooth muscle cell (SMC) contractility initially, but this effect was attenuated with age. These findings improve our understanding of microstructural and mechanical changes during the maladaptive vascular remodeling process, demonstrating a role for adventitial collagen fiber reorientation in the response to hypertension.NEW & NOTEWORTHY Endothelial dysfunction facilitates the reorganization of collagen fibers toward a more predominantly circumferential orientation with age, consequently promoting homeostatic normalization of passive circumferential stress and stretch in the vessel subjected to hypertension.

Abstract Lysyl oxidase (LOX) is the founding member of the LOX family proteins and mediates the conversion of lysine residues in collagen I and elastin precursors into highly reactive aldehydes, leading to crosslinking of extracellular matrix (ECM). LOX is upregulated in aggressive tumors with high stiffness, and its higher expression correlates with metastasis, therapy resistance, and worse clinical outcome; however, relatively LOX-specific, orally bioavailable inhibitors are still lacking. Here we discovered bi-thiazole derivatives as potent LOX inhibitors by combining a robust screening platform for drug-like molecules, cell- and recombinant protein-based assays. Structure-activity relationship analysis further identified a potent and relatively LOX-specific lead compound (LXG6403) that reduces collagen content and crosslinking, and fibronectin assembly, leading to increased chemoresponse in triple-negative breast cancer (TNBC) cell lines and PDX organoids in 3D collagen. LXG6403 shows favorable pharmacokinetic properties, reduces collagen content and crosslinking, as demonstrated by the state-of-the-art MALDI-MSI and MP-SHG analyses, respectively. This leads to better drug penetration, inhibition of FAK signaling, and induction of ROS generation/DNA damage, leading to G1 arrest and apoptosis in chemoresistant TNBC PDXs. Overall, our novel, potent, tolerable bi-thiazole LOX inhibitor enhances chemoresponse in TNBC, the deadliest breast cancer subtype. Citation Format: Metin Cetin, Ozge Saatci, Abdol-Hossein Rezaeian, Chintada N. Rao, Chad Beneker, Harrison Taylor, Breanna Pederson, Ioulia Chatzistamou, Brian Buckley, Susan Lessner, Peggi Angel, Campbell McInnes, Ozgur Sahin. Rewiring collagen architecture using a highly potent bi-thiazole inhibitor of LOX mediates chemosensitization in triple-negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 681.

Lysyl oxidase (LOX) is upregulated in highly stiff aggressive tumors, correlating with metastasis, resistance, and worse survival; however, there are currently no potent, safe, and orally bioavailable small molecule LOX inhibitors to treat these aggressive desmoplastic solid tumors in clinics. Here we discovered bi-thiazole derivatives as potent LOX inhibitors by robust screening of drug-like molecules combined with cell/recombinant protein-based assays. Structure-activity relationship analysis identified a potent lead compound (LXG6403) with ∼3.5-fold specificity for LOX compared to LOXL2 while not inhibiting LOXL1 with a competitive, time- and concentration-dependent irreversible mode of inhibition. LXG6403 shows favorable pharmacokinetic properties, globally changes ECM/collagen architecture, and reduces tumor stiffness. This leads to better drug penetration, inhibits FAK signaling, and induces ROS/DNA damage, G1 arrest, and apoptosis in chemoresistant triple-negative breast cancer (TNBC) cell lines, PDX organoids, and in vivo. Overall, our potent and tolerable bi-thiazole LOX inhibitor enhances chemoresponse in TNBC, the deadliest breast cancer subtype.

The murine aorta is a complex, heterogeneous structure that undergoes large and sometimes asymmetrical deformations under loading. For analytical convenience, mechanical behavior is predominantly described using global quantities that fail to capture critical local information essential to elucidating aortopathic processes. Here, in our methodological study, we used stereo digital image correlation (StereoDIC) to measure the strain profiles of speckle-patterned healthy and elastase-infused, pathological mouse aortas submerged in a temperature-controlled liquid medium. Our unique device rotates two 15-degree stereo-angle cameras that gather sequential digital images while simultaneously performing conventional biaxial pressure-diameter and force-length testing. A StereoDIC Variable Ray Origin (VRO) camera system model is employed to correct for high-magnification image refraction through hydrating physiological media. The resultant Green-Lagrange surface strain tensor was quantified at different blood vessel inflation pressures, axial extension ratios, and after aneurysm-initiating elastase exposure. Quantified results capture large, heterogeneous, inflation-related, circumferential strains that are drastically reduced in elastase-infused tissues. Shear strains, however, were very small on the tissue's surface. Spatially averaged StereoDIC-based strains were generally more detailed than those determined using conventional edge detection techniques.

Triple negative breast cancer (TNBC) is the most aggressive breast cancer subtype accounting for around 15% of all breast cancer patients and is responsible for 30% of breast cancer-related deaths. Although chemotherapy is the mainstay therapy for TNBC, development of resistance significantly reduces patients’ survival. Therefore, there is an urgent need to identify novel and effective treatment strategies to overcome chemoresistance. Recently, we identified hypoxia-induced ECM re-modeler, lysyl oxidase (LOX), a member of LOX family, as a key mediator of chemoresistance in TNBC. In this study, combining a robust screening platform for drug-like molecules and cell-based/recombinant protein assays, we identified bi-thiazole derivatives as novel potent LOX inhibitors. Further structure activity relationship (SAR) analysis resulted in two lead compounds: 6403, a relatively LOX-specific inhibitor, and 6415, a more LOX/LOXL2 dual inhibitor. Both compounds reduced collagen crosslinking and led to chemosensitization in TNBC cell lines in 3D culture and in chemoresistant TNBC PDX organoids. Furthermore, re-analyses of scRNA-Seq data of TNBC patients treated with neo-adjuvant chemotherapy with known chemoresponse or resistance showed that LOX+ cells were enriched upon chemotherapy only in treatment-refractory patients. Importantly, we identified a significant correlation between LOX and the gene sets of Reactive Oxygen Species (ROS) and DNA repair in TNBC patients treated with chemotherapy. Supporting this, increased chemotherapy penetration upon LOX inhibition resulted in elevated ROS levels and DNA damage in cells, leading to inhibition of FAK/Akt survival signaling. The efficacy of 6403 was tested in a chemoresistant TNBC PDX model where combination of doxorubicin with LOX inhibitor overcame doxorubicin resistance with no significant change in body weights. State-of-the-art MALDI-MSI and MP-SHG experiments showed efficient reduction of collagen content and crosslinking, respectively in PDX tumors upon LOX inhibition. Overall, these results show that novel bi-thiazole LOX inhibitors block collagen crosslinking and potentiates chemotherapy-induced ROS-DNA damage axis to overcome chemoresistance in TNBC. Citation Format: Metin Cetin, Ozge Saatci, Abdol-Hossein Rezaeian, Ozge Akbulut, Nageswara Rao Chintada, Harrison Taylor, Breanna Pederson, Ioulia Chatzistamou, Hamed Shateri Najafabadi, Susan Lessner, Peggi Angel, Campbell McInnes, Ozgur Sahin. Novel bi-thiazole LOX inhibitors to overcome chemotherapy resistance in triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 578.

Atherosclerosis, a chronic inflammatory disease affecting the large arteries, presents a global health risk. Accurate analysis of diagnostic images, like computed tomographic angiograms (CTAs), is essential for staging and monitoring the progression of atherosclerosis-related conditions, including peripheral arterial disease (PAD). However, manual analysis of CTA images is time-consuming and tedious. To address this limitation, we employed a deep learning model to segment the vascular system in CTA images of PAD patients undergoing femoral endarterectomy surgery and to measure vascular calcification from the left renal artery to the patella. Utilizing proprietary CTA images of 27 patients undergoing femoral endarterectomy surgery provided by Prisma Health Midlands, we developed a Deep Neural Network (DNN) model to first segment the arterial system, starting from the descending aorta to the patella, and second, to provide a metric of arterial calcification. Our designed DNN achieved 83.4% average Dice accuracy in segmenting arteries from aorta to patella, advancing the state-of-the-art by 0.8%. Furthermore, our work is the first to present a robust statistical analysis of automated calcification measurement in the lower extremities using deep learning, attaining a Mean Absolute Percentage Error (MAPE) of 9.5% and a correlation coefficient of 0.978 between automated and manual calcification scores. These findings underscore the potential of deep learning techniques as a rapid and accurate tool for medical professionals to assess calcification in the abdominal aorta and its branches above the patella.

Pathological alterations in the human vascular system underlie many chronic diseases, such as atherosclerosis and aneurysms. However, manually analyzing diagnostic images of the vascular system, such as computed tomographic angiograms (CTAs) is a time-consuming and tedious process. To address this issue, we propose a deep learning model to segment the vascular system in CTA images of patients undergoing surgery for peripheral arterial disease (PAD). Our study focused on accurately segmenting the vascular system (1) from the descending thoracic aorta to the iliac bifurcation and (2) from the descending thoracic aorta to the knees in CTA images using deep learning techniques. Our approach achieved average Dice accuracies of 93.5% and 80.6% in test dataset for (1) and (2), respectively, highlighting its high accuracy and potential clinical utility. These findings demonstrate the use of deep learning techniques as a valuable tool for medical professionals to analyze the health of the vascular system efficiently and accurately. Please visit the GitHub page for this paper at https://github.com/pip-alireza/TransOnet.

The viscoelastic properties of aortic tissue dictate vessel behavior in certain disease states, injury modalities, and during some endovascular procedures. We characterized the viscoelastic response of porcine abdominal aortic tissue via test and simulation to demonstrate the utility of a viscoelastic anisotropic (VA) constitutive model. In this study, the measured stress relaxation response for five samples and uniaxial tensile testing for one sample measured with the digital image correlation (DIC) technique were used to identify material parameters for the VA model using an inverse method through finite element analysis (FEA). Based on the stress relaxation test, the values of the stress-like parameter $$\mu$$ , relative stiffness of the fibers $${k}_{1}$$ , dimensionless parameter $${k}_{2}$$ , angle of fibers $$\gamma$$ , dispersion parameter $$\kappa$$ , relaxation times for the ground matrix $${\mathsf{T}}_{g1}$$ and collagen fibers $${\mathsf{T}}_{f1}$$ and the dimensionless parameters for the ground matrix $${\beta }_{g1}$$ and collagen fibers $${\beta }_{f1}$$ for 0 degree specimen orientation were 12.1 ± 8.96 kPa, 77.3 ± 46.4 kPa, 0.032 ± 0.043, 30.25 ± 6.81°, 0.19 ± 0.06, 0.028 ± 0.016 s, 92.76 ± 26.51 s, 3.46 ± 3.78, 0.24 ± 0.08 and for 90 degree specimen orientation were 13.7 ± 7.7 kPa, 72.6 ± 35.4 kPa, 2.18 ± 4.12, 55.35 ± 7.12°, 0.22 ± 0.06, 23.51 ± 38.90 s, 81.52 ± 29.16 s, 5.14 ± 8.72, 0.21 ± 0.05, respectively. The validation revealed an overall good agreement from cycles 2 and 3 based on uniaxial tensile tests and surface strains data from DIC measurements with the material parameters from inverse analysis using FEA for the response in cycle 1. The identified material model and numerical simulations provide a comprehensive description of the viscoelastic behavior of the aortic wall tissue and a quantitative understanding of the spatial and directional variability underlying aortic tissue mechanical behavior.

Thoracic aortic aneurysm is one of the manifestations of Marfan syndrome (MFS) that is known to affect men more severely than women. However, the incidence of MFS is similar between men and women. The aim of this study is to show that during pathological aortic dilation, sex-dependent severity of thoracic aortopathy in a mouse model of MFS translates into sex-dependent alterations in cells and matrix of the ascending aorta, consequently affecting aortic biomechanics. Fibrillin-1 C1041G/+ (Het) mice were used as a mouse model of MFS. Ultrasound measurements from 3 to 12 mo showed increased aortic diameter in Het aorta, with larger percentage increase in diameter for males compared with females. Immunohistochemistry showed decreased contractile smooth muscle cells in Het aortic wall compared with healthy aorta, which was accompanied by decreased contractility measured by wire myography. Elastin autofluorescence, second-harmonic generation microscopy of collagen fibers, and passive biomechanical assessments using myography showed more severe damage to elastin fibers, increased medial fibrosis, and increased stiffness of the aortic wall in MFS males but not females. Male and female Het mice showed increased expression of Sca-1-positive adventitial progenitor cells versus controls at young ages. In agreement with clinical data, Het mice demonstrate sex-dependent severity of thoracic aortopathy. It was also shown that aging exacerbates the disease state especially for males. Our findings suggest that female mice are protected from progression of aortic dilation at early ages, leading to a lag in aneurysm growth. NEW & NOTEWORTHY Male Fbn1(C1041G/+ )mice show more severe thoracic aortic changes compared with females, especially at 12 mo of age. Up to 6 mo of age, Sca-1(+) smooth muscle progenitor cells are more abundant in the adventitia of both male and female Fbn1 Het mice compared with wild types (WTs). Male and female Het mice show similar patterns of expression of Sca-1(+) cells at early ages.

Vascular cells restructure extracellular matrix in response to aging or changes in mechanical loading. Here, we characterized collagen architecture during age-related aortic remodeling in atherosclerosis-prone mice. We hypothesized that changes in collagen fiber orientation reflect an altered balance between passive and active forces acting on the arterial wall. We examined two factors that can alter this balance, endothelial dysfunction and reduced smooth muscle cell (SMC) contractility. Collagen fiber organization was visualized by second-harmonic generation microscopy in aortic adventitia of apolipoprotein E (apoE) knockout (KO) mice at 6 wk and 6 mo of age on a chow diet and at 7.5 mo of age on a Western diet (WD), using image analysis to yield mean fiber orientation. Adventitial collagen fibers became significantly more longitudinally oriented with aging in apoE knockout mice on chow diet. Conversely, fibers became more circumferentially oriented with aging in mice on WD. Total collagen content increased significantly with age in mice fed WD. We compared expression of endothelial nitric oxide synthase and acetylcholine-mediated nitric oxide release but found no evidence of endothelial dysfunction in older mice. Time-averaged volumetric blood flow in all groups showed no significant changes. Wire myography of aortic rings revealed decreases in active stress generation with age that were significantly exacerbated in WD mice. We conclude that the aorta displays a distinct remodeling response to atherogenic stimuli, indicated by altered collagen organization. Collagen reorganization can occur in the absence of altered hemodynamics and may represent an adaptive response to reduced active stress generation by vascular SMCs.NEW & NOTEWORTHY The following major observations were made in this study: 1) aortic adventitial collagen fibers become more longitudinally oriented with aging in apolipoprotein E knockout mice fed a chow diet; 2) conversely, adventitial collagen fibers become more circumferentially oriented with aging in apoE knockout mice fed a high-fat diet; 3) adventitial collagen content increases significantly with age in mice on a high-fat diet; 4) these alterations in collagen organization occur largely in the absence of hemodynamic changes; and 5) circumferential reorientation of collagen is associated with decreased active force generation (contractility) in aged mice on a high-fat diet.

Abdominal aortic aneurysm (AAA) disease causes dilation of the aorta, leading to aortic rupture and death if not treated early. It is the 14th leading cause of death in the U.S. and 10th leading cause of death in men over age 55, affecting thousands of patients. Despite the prevalence of AAA, no safe and efficient pharmacotherapies exist for patients. The deterioration of the elastic lamina in the aneurysmal wall is a consistent feature of AAAs, making it an ideal target for delivering drugs to the AAA site. In this research, we conjugated nanoparticles with an elastin antibody that only targets degraded elastin while sparing healthy elastin. After induction of aneurysm by 4-week infusion of angiotensin II (Ang II), two biweekly intravenous injections of pentagalloyl glucose (PGG)-loaded nanoparticles conjugated with elastin antibody delivered the drug to the aneurysm site. We show that targeted delivery of PGG could reverse the aortic dilation, ameliorate the inflammation, restore the elastic lamina, and improve the mechanical properties of the aorta at the AAA site. Therefore, simple iv therapy of PGG loaded nanoparticles can be an effective treatment option for early to middle stage aneurysms to reverse disease progression and return the aorta to normal homeostasis.

microRNA-155 (miR155) is pro-atherogenic; however, its role in vascular calcification is unknown. In this study, we aim to examine whether miR155 regulates vascular calcification and to understand the underlying mechanism. Quantitative real-time PCR showed that miR155 is highly expressed in human calcific carotid tissue and positively correlated with the expression of osteogenic genes. Wound-healing assay and TUNEL staining showed deletion of miR155 inhibited vascular smooth muscle cell (VSMC) migration and apoptosis. miR155 deficiency attenuated calcification of cultured mouse VSMCs and aortic rings induced by calcification medium, whereas miR155 overexpression promoted VSMC calcification. Compared with wild-type mice, miR155(-/-) mice showed significant resistance to vitamin D3 induced vascular calcification. Protein analysis showed that miR155 deficiency alleviated the reduction of Rictor, increased phosphorylation of Akt at S473 and accelerated phosphorylation and degradation of FOXO3a in cultured VSMCs and in the aortas of vitamin D3-treated mice. A PI3K inhibitor that suppresses Akt phosphorylation increased, whereas a pan-caspase inhibitor that suppresses apoptosis reduced VSMC calcification; and both inhibitors diminished the protective effects of miR155 deficiency on VSMC calcification. In conclusion, miR155 deficiency attenuates vascular calcification by increasing Akt phosphorylation and FOXO3a degradation, and thus reducing VSMC apoptosis induced by calcification medium.

Tristetraprolin (TTP), an mRNA binding and decaying protein, plays a significant role in controlling inflammation by decaying mRNAs encoding inflammatory cytokines such as TNFalpha. We aimed to test a hypothesis that TTP in bone marrow (BM) cells regulates atherogenesis by modulating inflammation and lipid metabolism through the modulation of oxidative stress pathways by TTP target genes. In a BM transplantation study, lethally irradiated atherogenic LDLR-/- mice were reconstituted with BM cells from either wild type (TTP+/+) or TTP knockout (TTP-/-) mice, and fed a Western diet for 12 weeks. We made the following observations: (1) TTP-/- BM recipients display a significantly higher systemic and multi-organ inflammation than TTP+/+ BM recipients; (2) BM TTP deficiency modulates hepatic expression of genes, detected by microarray, involved in lipid metabolism, inflammatory responses, and oxidative stress; (3) TTP-/- BM derived macrophages increase production of mitochondrial reactive oxygen species (mtROS); (4) BM-TTP-/- mice display a significant reduction in serum VLDL/LDL levels, and attenuated hepatic steatosis compared to controls; and (5) Reduction of serum VLDL/LDL levels offsets the increased inflammation, resulting in no changes in atherosclerosis. These findings provide a novel mechanistic insight into the roles of TTP-mediated mRNA decay in bone marrow-derived cells in regulating systemic inflammation, oxidative stress, and liver VLDL/LDL biogenesis.

Elastin is a key structural protein and its pathological degradation deterministic in aortic aneurysm (AA) outcomes. Unfortunately, using current diagnostic and clinical surveillance techniques the integrity of the elastic fiber network can only be assessed invasively. To address this, we employed fragmented elastin-targeting gold nanoparticles (EL-AuNPs) as a diagnostic tool for the evaluation of unruptured AAs. Electron dense EL-AuNPs were visualized within AAs using micro-computed tomography (micro-CT) and the corresponding Gold-to-Tissue volume ratios quantified. The Gold-to-Tissue volume ratios correlated strongly with the concentration (0, 0.5, or 10 U/mL) of infused porcine pancreatic elastase and therefore the degree of elastin damage. Hyperspectral mapping confirmed the spatial targeting of the EL-AuNPs to the sites of damaged elastin. Nonparametric Spearman's rank correlation indicated that the micro-CT-based Gold-to-Tissue volume ratios had a strong correlation with loaded (ρ = 0.867, p-val = 0.015) and unloaded (ρ = 0.830, p-val = 0.005) vessel diameter, percent dilation (ρ = 0.976, p-val = 0.015), circumferential stress (ρ = 0.673, p-val = 0.007), loaded (ρ = − 0.673, p-val = 0.017) and unloaded (ρ = − 0.697, p-val = 0.031) wall thicknesses, circumferential stretch (ρ = − 0.7234, p-val = 0.018), and lumen area compliance (ρ = − 0.831, p-val = 0.003). Likewise, in terms of axial force and axial stress vs. stretch, the post-elastase vessels were stiffer. Collectively, these findings suggest that, when combined with CT imaging, EL-AuNPs can be used as a powerful tool in the non-destructive estimation of mechanical and geometric features of AAs.

To measure the inhomogeneous 3D-strain fields present during inflation-extension testing of physiologically submerged micro-aneurysms, a Stereo Digital Image Correlation (StereoDIC) microscopy system is developed that revolves 15 degrees stereo-angle cameras around a centrally-mounted target. Calibration is performed using submerged dot patterns and system accuracy verified using strain and deformation analyses for rigid body motions of speckle-patterned, micro-aneurysmal surrogates. In terms of the Green-Lagrange strain tensor and the 3D displacement fields, the results are stable even after 120 minutes, with maxima in both strain bias and strain standard deviation less than 2E-03 for all components, and micron-level displacement standard deviation.

In cases of severe carotid artery stenosis (CAS), carotid endarterectomy (CEA) is performed to recover lumen patency and alleviate stroke risk. Under current guidelines, the decision to surgically intervene relies primarily on the percent loss of native arterial lumen diameter within the stenotic region (i.e. the degree of stenosis). An underlying premise is that the degree of stenosis modulates flow-induced wall shear stress elevations at the lesion site, and thus indicates plaque rupture potential and stroke risk. Here, we conduct a retrospective study on pre-CEA computed tomography angiography (CTA) images from 50 patients with severe internal CAS (>60% stenosis) to better understand the influence of plaque and local vessel geometry on local hemodynamics, with geometrical descriptors that extend beyond the degree of stenosis. We first processed CTA images to define a set of multipoint geometric metrics characterizing the stenosed region, and next performed computational fluid dynamics simulations to quantify local wall shear stress and associated hemodynamic metrics. Correlation and regression analyses were used to relate obtained geometric and hemodynamic metrics, with inclusion of patient sub-classification based on the degree of stenosis. Our results suggest that in the context of severe CAS, prediction of shear stress-based metrics can be enhanced by consideration of readily available, multipoint geometric metrics in addition to the degree of stenosis.