Quantifying Smooth Muscles Regional Organization in the Rat Bladder Using Immunohistochemistry, Multiphoton Microscopy and Machine Learning.

The smooth muscle bundles (SMBs) in the bladder act as contractile elements which enable the bladder to void effectively. In contrast to skeletal muscles, these bundles are not highly aligned, rather they are oriented more heterogeneously throughout the bladder wall. In this work, for the first time, this regional orientation of the SMBs is quantified across the whole bladder, without the need for optical clearing or cryosectioning. Immunohistochemistry staining was utilized to visualize smooth muscle cell actin in multiphoton microscopy (MPM) images of bladder smooth muscle bundles (SMBs). Feature vectors for each pixel were generated using a range of filters, including Gaussian blur, Gaussian gradient magnitude, Laplacian of Gaussian, Hessian eigenvalues, structure tensor eigenvalues, Gabor, and Sobel gradients. A Random Forest classifier was subsequently trained to automate the segmentation of SMBs in the MPM images. Finally, the orientation of SMBs in each bladder region was quantified using the CT-FIRE package. This information is essential for biomechanical models of the bladder that include contractile elements.

Effect of Beta Blockers on the Hemodynamics and Thrombotic Risk of Coronary Artery Aneurysms in Kawasaki Disease.

This study aims to simulate beta blockers' (BB) effects on coronary artery aneurysms' (CAA) hemodynamics and thrombotic risk in Kawasaki disease (KD). BB are recommended in cases of large aneurysms due to their anti-ischemic effect. Coronary blood flow (CBF) was simulated in KD patient-specific CAA models using computational fluid dynamics. Hemodynamic indices that correlate with thrombotic risk were calculated following two possible responses to BB: (1) preserved coronary flow (third BB generation) and (2) reduction in coronary flow (first and second BB generations) at reduced heart rate. Following CBF reduction scenario, mean TAWSS and HOLMES significantly decreased compared to normal conditions, leading to a potential increase in thrombotic risk. Preserved CBF at lower heart rates, mimicking the response to vasodilating BBs, does not significantly affect local CAA hemodynamics compared with baseline, while achieving the desired anti-ischemic effects. Different BB generations lead to different hemodynamic responses in CAA.

Predicting hemodynamic indices in coronary artery aneurysms using response surface method: An application in Kawasaki disease.

BACKGROUND AND OBJECTIVES: Coronary artery aneurysms (CAA), such as those in Kawasaki Disease (KD), induce hemodynamic alterations associated with thrombosis and atherosclerosis. Current clinical routines assess the risk level of the CAA cases based on the Z-Score, which considers the body surface area (BSA) and the CAA's diameter. A full geometric characterization and impact on hemodynamic metrics and their correlation with thrombotic risks have not been systematically investigated. The goal of this study was to investigate the effect of CAA shape indices on local hemodynamics using the response surface method (RSM) through considering KD applications. METHODS: Transient computational fluid dynamics (CFD) simulations have been performed on idealized CAA geometries defined by geometrical ratios combining neck diameter, CAA diameter and CAA length. The results were used to develop full quadratic regression models of the indices using the response surface method (RSM). Validation using patient-specific KD models was performed. RESULTS: The results indicated that the aneurysm diameter is the main determining factor in the thrombotic risk of CAA patients, which is consistent with clinical guidelines. Furthermore, it was observed that in most CAA cases having the same diameter, the one with the shorter length experiences higher RRT values, indicating flow stagnation and circulation. CONCLUSIONS: The developed regression models can be used to ultimately assess the thrombotic risk of CAA cases from the hemodynamic perspective. The applicability of these models was tested on 2 KD patient specific models, with close values achieved between the models and the patient-specific results.