Citations

Introduction: In seniors, the prevalence of abdominal aortic aneurysms (AAA) is high (9-10%). We aim to characterize AAA growth rates (slow vs. rapid) to help inform management strategies, including individualized imaging surveillance frequency. Hypothesis: Modeling thrombosis may improve the characterization of AAAs' growth status. Methods: 3D geometrical AAA models with and without thrombosis (vessel lumen only) were generated for 70 human subjects using available contrast-enhanced CTA data. AAA growth rates were categorized as slow (< 5 mm/year) or rapid (≥ 5 mm/year) based on serial imaging. Python scripts were used to calculate geometrical parameters (83) with and without thrombosis. Patient-specific relevant health information was retrieved through a review of medical records. Support vector machine (SVM), a well-established machine learning method, was run with 10-fold cross-validation (100 iterations) to assess the predictive accuracy. Results: Among 70 AAAs studied, the ratio between rapidly-growing and slowly-growing was nearly 1:2. The combination of antihypertensive medication, coronary artery disease, juxta-aneurysm aortic size, and five geometrical parameters quantifying the extent of thrombosis provided the best accuracy for AAA's growth status. The area under receiving operating curve (AUROC) was 0.85, and total accuracy was 0.81, with 57% and 93% of rapidly- and slowly-growing AAAs correctly identified, respectively. Excluding patients with aneurysm thrombus, the AUROC and accuracy in predicting rapidly-growing AAAs decreased to 0.82 and 48%, respectively. Conclusions: machine-learning-based predictive modeling appears feasible for characterizing AAA's growth rate status. Manual aortic image segmentation, required for data analytics, is labor-intensive (on average, 1 hour). Leveraging artificial intelligence-based segmentation methodology may provide an automated solution to improve workflow and feasibility.

Pulmonary edema is common in patients with congestive heart failure. Extravascular lung water (EVLW) correlates to the disease prognosis but the assessment is challenging. The current standard method, computed tomography (CT), poses a significant logistic burden and exposes patents to ionizing radiation. Non-invasive lung ultrasound (LUS) is introduced to subjectively evaluate B-lines for EVLW but results in significant inter-observer variability. We have developed ultrasound vibro-elastography (USVE) to safely measure lung surface wave speed quantitatively. In this abstract, we presented the technique for analyzing water content in a lung phantom model. A sponge is used as the lung phantom. Twelve water contents were injected in the phantom for different EVLW values. The mass density of the phantom was measured for each water content. Wave propagation was generated at five frequencies between 100 Hz and 300 Hz in the phantom, and the surface wave speeds were collected. The viscoelasticity was derived from the wave speed dispersion with frequency. The obtained surface wave speeds showed no clear correlation with different water content. The elasticity and viscosity, however, were found increased with water content. This research pinpoints the likelihood and possible direction for USVE to assess EVLW for patients with pulmonary edema.

Glaucoma is the leading cause of irreversible blindness worldwide. Ocular biomechanical properties have been implicated in glaucoma pathogenesis, but existing commercial devices cannot determine changes in specific tissues. We recently performed a study to compare corneal wave speed (a measure of corneal elasticity) and ocular rigidity (a whole eye measurement of ocular biomechanics) between glaucomatous and normal eyes. Twenty glaucomatous eyes from 10 patients and 20 normal eyes from 13 controls, matched for age, intraocular pressure (IOP), and axial length were included. Ocular rigidity was calculated based on the difference in supine IOP by pneumatonometry with and without a 10-g weight. Corneal wave speed was determined by ultrasound surface wave elastography in which a small, 0.1 s harmonic vibration at 100 Hz was generated through the closed eyelids. Wave propagation was captured by an ultrasound transducer, and wave speed was determined from the phase change with distance. No significant differences in corneal wave speed between glaucomatous and normal eyes were detected (P = 0.17). However, ocular rigidity was significantly lower in glaucomatous eyes (0.0218 ± 0.0033 vs 0.0252 ± 0.0050 μl−1, P = 0.01). While lower ocular rigidity is consistent with altered biomechanics in glaucoma, the lack of a difference in corneal wave speed suggests that corneal tissue may not be significantly affected, and scleral changes likely play a more important role.

Papilledema is optic nerve swelling caused by increased intracranial hypertension, which has the potential to cause significant vision loss. Papilledema from idiopathic intracranial hypertension (IIH) is typically bilateral and symmetric, but can sometimes be asymmetric and even unilateral. The cause for this asymmetry is unknown. The purpose of this study was to develop ultrasound vibro-elastography (UVE) for assessing patients with papilledema to evaluate for biomechanical differences in these eyes. Nine patients with papilledema from IIH and 9 age-matched healthy control subjects were enrolled. A local harmonic vibration was used to generate wave propagation through the eyelid. Three excitation frequencies of 100, 150, and 200 Hz were used. A 6.4 MHz ultrasound probe was used to measure wave propagation in the eye structures. Wave speeds were measured in the posterior sclera of the maculae. The magnitudes of the wave speed of the IIH patients’ posterior sclera were significantly higher than those of healthy subjects. In patients with unilateral papilledema, the wave speed of the posterior sclera were higher in the eyes with papilledema than in the contralateral eyes without papilledema. UVE provides a noninvasive technique to measure the wave speed of posterior sclera, which is stiffer in eyes with papilledema.

Precis: Ocular biomechanics were compared between treated glaucoma patients and healthy subjects matched for age, intraocular pressure (IOP), and axial length. There was no difference in corneal wave propagation speed, but ocular rigidity was lower in glaucomatous eyes. Purpose: Ocular biomechanical properties are important in understanding glaucoma pathogenesis but the affected tissues are unclear. In this study, we compared corneal wave speed (a measure of corneal elasticity) and ocular rigidity coefficient between glaucomatous and normal eyes. Materials and Methods: Twenty glaucomatous eyes from 10 patients and 20 normal eyes from 13 controls, matched for age, IOP, and axial length were included. Ocular rigidity was calculated based on the difference in supine IOP by pneumatonometry with and without a 10-g weight. Corneal wave speed was determined by ultrasound surface wave elastography. A small, 0.1-second harmonic vibration at 100 Hz was generated through the closed eyelids. Wave propagation was captured by an ultrasound transducer, and wave speed was determined from the phase change with distance. Comparisons were performed using generalized estimating equation models. Results: There were no significant differences in corneal wave speed between glaucomatous and normal eyes (2.16±0.25 vs. 2.07±0.16 m/s, P=0.17). However, ocular rigidity was significantly lower in glaucomatous eyes (0.0218±0.0033 vs. 0.0252±0.0050/μL, P=0.01). Corneal wave speed was not correlated with age and IOP in either group (P≥0.23) but was correlated with ocular rigidity (R=0.48, P=0.02) and inversely correlated with axial length (R=−0.53, P=0.01) in glaucomatous eyes. Conclusion: Glaucomatous eyes tend to have lower ocular rigidity than healthy eyes with similar age, IOP, and axial length. However, the lack of a difference in corneal wave speed suggests that corneal tissue may not be significantly affected, and scleral changes likely play a more important role in glaucoma.

As a member of the phylum Cnidaria, the body wall of hydra is organized as an epithelium bilayer (ectoderm and endoderm) with an intervening extracellular matrix (ECM). Previous studies have established the general molecular structure of hydra ECM and indicate that it is organized as two subepithelial zones that contain basement membrane components such as laminin and a central fibrous zone that contains interstitial matrix components such as a unique type I fibrillar collagen. Because of its simple structure and high regenerative capacity, hydra has been used as a developmental model to study cell-ECM interaction during epithelial morphogenesis. The current study extends previous studies by focusing on the relationship of ECM biogenesis to epithelial morphogenesis in hydra, as monitored during head regeneration or after simple incision of the epithelium. Histological studies indicated that decapitation or incision of the body column resulted in an immediate retraction of the ECM at the wound site followed by a re-fusion of the bilayer within 1 hour. After changes in the morphology of epithelial cells at the regenerating pole, initiation of de novo biogenesis of an ECM began within hours while full reformation of the mature matrix required approximately 2 days. These processes were monitored using probes to three matrix or matrix-associated components: basement membrane-associated hydra laminin β1 chain (HLM-β1), interstitial matrix-associated hydra fibrillar collagen (Hcol-I) and hydra matrix metalloproteinase (HMMP). While upregulation of mRNA for both HLM-β1 and Hcol-I occurred by 3 hours, expression of the former was restricted to the endoderm and expression of the latter was restricted to the ectoderm. Upregulation of HMMP mRNA was also associated with the endoderm and its expression paralleled that for HLM-β1. As monitored by immunofluorescence, HLM-β1 protein first appeared in each of the two subepithelial zones (basal lamina) at about 7 hours, while Hcol-I protein was first observed in the central fibrous zone (interstitial matrix) between 15 and 24 hours. The same temporal and spatial expression pattern for these matrix and matrix-associated components was observed during incision of the body column, thus indicating that these processes are a common feature of the epithelium in hydra. The correlation of loss of the ECM, cell shape changes and subsequent de novo biogenesis of matrix and matrix-associated components were all functionally coupled by antisense experiments in which translation of HLM-β1 and HMMP was blocked and head regeneration was reversibly inhibited. In addition, inhibition of translation of HLM-β1 caused an inhibition in the appearance of Hcol-I into the ECM, thus suggesting that binding of HLM-β1 to the basal plasma membrane of ectodermal cells signaled the subsequent discharge of Hcol-I from this cell layer into the newly forming matrix. Given the early divergence of hydra, these studies point to the fundamental importance of cell-ECM interactions during epithelial morphogenesis.

Objective: The objective of this study is to predict in vivo lung mass density for patients with interstitial lung disease using different gradient boosting decision tree (GBDT) algorithms based on measurements from lung ultrasound surface wave elastography (LUSWE) and pulmonary function testing (PFT). Methods: Age and weight of study subjects (57 patients with interstitial lung disease and 20 healthy subjects), surface wave speeds at three vibration frequencies (100, 150, and 200 Hz) from LUSWE, and predicted forced expiratory volume (FEV1% pre) and ratio of forced expiratory volume to forced vital capacity (FEV1%/FVC%) from PFT were used as inputs while lung mass densities based on the Hounsfield Unit from high resolution computed tomography (HRCT) were used as labels to train the regressor in three GBDT algorithms, XGBoost, CatBoost, and LightGBM. 80% (20%) of the dataset was used for training (testing). Results: The results showed that predictions using XGBoost regressor obtained an accuracy of 0.98 in the test dataset. Conclusion: The obtained results suggest that XGBoost regressor based on the measurements from LUSWE and PFT may be able to noninvasively assess lung mass density in vivo for patients with pulmonary disease.

Ultrasonography is not widely used for lung assessment because ultrasound cannot image deep lung tissue. Many lung diseases including interstitial lung disease (ILD) are associated with changes in lung's elastic properties. ILD includes multiple serious lung disorders associated with lung fibrosis and can lead to respiratory failure and pulmonary hypertension. High-resolution CT (HRCT) is the clinical standard for diagnosing lung fibrosis, but it results in increased radiation exposure for patients. Lung fibrosis is associated with stiffened lung parenchyma. Current clinical techniques including HRCT cannot measure lung elastic properties. Most ILDs are typically distributed in the lung's peripheral and subpleural regions. We developed noninvasive lung ultrasound surface wave elastography (LUSWE) to measure lung surface wave speed safely and quickly. In this abstract, we will present some basics for LUSWE. We will also present its clinic application for assessing ILD. We studied 30 healthy controls, 16 mild ILD patients, 45 moderate ILD patients, and 27 severe ILD patients. Lung surface wave speed has good sensitivity and specificity for separating ILD patients from healthy subjects as well as for separating mild ILD patients from healthy subjects. LUSWE is useful for other lung disorders such as pulmonary edema.

Zebrafish are being increasingly used as animal models for human diseases such as cardiomyopathy and neuroblastoma because zebrafish have a nearly fully sequenced genome to humans. One pilot study is to develop zebrafish echocardiography. Because the heart of a zebrafish is small, a high frequency ultrasound system (50–80 MHz) is used for imaging. B-Mode imaging is analyzed for quantification of ejection fraction (EF), end-systolic volume (ESV), and end-diastolic volume (EDV). Pulse-wave Doppler (PWD) is used to calculate the E/A ratio (the peak velocities of E and A waves) and myocardial performance index (MPI). Techniques for improving image quality and repeatability of zebrafish echocardiography are discussed. Another pilot study is to develop zebrafish ultrasound vibro-elastography (ZUVE) for measuring the elastic properties of zebrafish. An adult female zebrafish is anesthetized for 3 min. A 0.1-s gentle harmonic vibration is generated on the tail of a zebrafish using a sphere tip indenter with a 3 mm diameter. Shear wave propagation in the zebrafish is measured using a high frequency 18 MHz ultrasound linear array probe. We conclude that ZUVE is safe, fast, and noninvasive and feasible for testing the elastic properties of zebrafish.

ObjectivesThe aim of this study was to assess bleomycin‐induced pulmonary fibrosis on ex vivo mouse lungs using ultrasound image grading and texture analysis.MethodsExcised mouse lungs were divided into 3 groups: control, mild fibrosis, and severe fibrosis based on the monitored indicators of health. B‐mode ultrasound images were obtained via scanning the mouse lungs ex vivo. The surface smoothness, echo density, and angle of lesions or the lung margin were graded, and the imaging contrast, correlation, homogeneity, and entropy were assessed via texture analysis.ResultsThe grades of surface smoothness, echo density, and angle were statistically higher for the severe fibrosis group compared with those of the control and mild fibrosis groups (P < .05). In addition, statistically significant differences in the contrast, correlation, and homogeneity between mild and severe fibrosis groups were observed (P < .05).ConclusionsThe results obtained in this study suggest that ultrasound image grading and texture analysis are valuable and meaningful methods for assessing pulmonary fibrosis in a bleomycin mouse model.