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Three-dimensional analysis of the thoracic aorta microscopic deformation during intraluminal pressurization.

ABSTRACT: The aorta is composed of various constituents with different mechanical properties. This heterogeneous structure implies non-uniform deformation in the aorta, which could affect local cell functions. The present study investigates 3D strains of the aorta at a cell scale induced by intraluminal pressurization. After resected mouse, thoracic aortas were stretched to their in vivo length, and the aortas were pressurized at 15, 40, 80, 120, and 160 mmHg. Images of autofluorescent light of elastin were captured under a two-photon microscope. From the movement of markers in elastic laminas (ELs) created by photo-bleaching, 3D strains (???, ?zz, ?rr, ?r?, ?rz, ??z) between two neighboring ELs in the circumferential (?), longitudinal (z), and radial (r) directions with reference to the dimensions at 15 mmHg were calculated. The results demonstrated that the average of shear strain ?r? was almost 0 in a physiological pressure range (from 80 to 120 mmHg) with an absolute value |?r?| changing approximately by 5%. This indicates that ELs experience radial-circumferential shear at the cell scale, but not at the whole tissue scale. The normal strains in the circumferential ??? and longitudinal direction ?zz were positive but that in the radial direction ?rr was almost 0, which demonstrates that aortic tissue is not an incompressible material. The first principal direction in the radial-circumferential plane was 29°?±?13° from the circumferential direction. We show that the aorta is not simply stretched in the circumferential direction during pressurization and that cells in the aorta undergo complex deformations by nature.

SUBMITTER: Sugita S

PROVIDER: S-EPMC7005079 | biostudies-literature | 2020 Feb

REPOSITORIES: biostudies-literature

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Three-dimensional analysis of the thoracic aorta microscopic deformation during intraluminal pressurization.

Sugita Shukei S Kato Masaya M Wataru Fukui F Nakamura Masanori M

Biomechanics and modeling in mechanobiology 20190711 1

The aorta is composed of various constituents with different mechanical properties. This heterogeneous structure implies non-uniform deformation in the aorta, which could affect local cell functions. The present study investigates 3D strains of the aorta at a cell scale induced by intraluminal pressurization. After resected mouse, thoracic aortas were stretched to their in vivo length, and the aortas were pressurized at 15, 40, 80, 120, and 160 mmHg. Images of autofluorescent light of elastin we ...[more]

PMID: 31297645

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Project description:BackgroundAccurate assessment of the aortic annulus (AA) dimension and judgment of thoracic aorta aneurysm is crucial for patients with aortic regurgitation (AR) before surgery. The aim of this study was to evaluate the accuracy and reproducibility of three-dimensional transesophageal echocardiography (3D-TEE) methods for AA measurement and explore the predictive value of the AA dimensions obtained by 3D-TEE for high-risk thoracic aorta aneurysms using the gold standard of multi-slice computed tomography (MSCT).Methods3D-TEE was performed on 111 patients with pure moderate-to-severe AR, and MSCT examination was conducted simultaneously. AA dimensions were obtained using reconstruction software for these two imaging techniques. Thoracic aortic diameters at standard anatomic landmarks were also measured by MSCT. All patients were divided into two groups depending on the presence of high-risk thoracic aorta aneurysms.ResultsCompared to MSCT, 3D-TEE overestimated all AA parameters. However, no statistically significant differences were found in the average bias between methods (minimum diameter: 26.07±3.57 vs. 25.88±3.68 mm, P=0.52; maximum diameter: 32.30±2.68 vs. 31.78±4.06 mm, P=0.11; area: 669.76±155.19 vs. 660.05±168.28 mm2, P=0.44; perimeter: 93.52±10.42 vs. 92.26±11.71 mm, P=0.12). 3D-TEE demonstrated good correlations with MSCT measurement for AA minimum diameter, maximum diameter, area, and perimeter (r=0.63, 0.64, 0.74, 0.69, P<0.05 for all). According to the multivariate logistic regression analysis, the AA minimum diameter obtained by 3D-TEE was the best predictor for the presence of high-risk thoracic aorta aneurysms. The sensitivity and specificity for prediction were 84.6% and 63.9%, respectively, for an AA minimum diameter ≥25.74 mm (AUC: 0.759, 95% CI: 0.668-0.850).ConclusionsAA measurements obtained by the 3D-TEE method are feasible and reliable for patients with pure AR. The AA minimum diameter measured by 3D-TEE can effectively predict the presence of high-risk thoracic aorta aneurysms.

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Project description:PurposeTo implement an integrated reconstruction pipeline including a graphics processing unit (GPU)-based convolutional neural network (CNN) architecture and test whether it reconstructs four-dimensional non-Cartesian, non-contrast material-enhanced MR angiographic k-space data faster than a central processing unit (CPU)-based compressed sensing (CS) reconstruction pipeline, without significant losses in data fidelity, summed visual score (SVS), or arterial vessel-diameter measurements.Materials and methodsRaw k-space data of 24 patients (18 men and six women; mean age, 56.8 years ± 11.8 [standard deviation]) suspected of having thoracic aortic disease were used to evaluate the proposed reconstruction pipeline derived from an open-source three-dimensional CNN. For training, 4800 zero-filled images and the corresponding CS-reconstructed images from 10 patients were used as input-output pairs. For testing, 6720 zero-filled images from 14 different patients were used as inputs to a trained CNN. Metrics for evaluating the agreement between the CNN and CS images included reconstruction times, structural similarity index (SSIM) and normalized root-mean-square error (NRMSE), SVS (3 = nondiagnostic, 9 = clinically acceptable, 15 = excellent), and vessel diameters.ResultsThe mean reconstruction time was 65 times and 69 times shorter for the CPU-based and GPU-based CNN pipelines (216.6 seconds ± 40.5 and 204.9 seconds ± 40.5), respectively, than for CS (14 152.3 seconds ± 1708.6) (P < .001). Compared with CS as practical ground truth, CNNs produced high data fidelity (SSIM = 0.94 ± 0.02, NRMSE = 2.8% ± 0.4) and not significantly different (P = .25) SVS and aortic diameters, except at one out of seven locations, where the percentage difference was only 3% (ie, clinically irrelevant).ConclusionThe proposed integrated reconstruction pipeline including a CNN architecture is capable of rapidly reconstructing time-resolved volumetric cardiovascular MRI k-space data, without a significant loss in data quality, thereby supporting clinical translation of said non-contrast-enhanced MR angiograms. Supplemental material is available for this article. © RSNA, 2020.

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Three-dimensional analysis of the thoracic aorta microscopic deformation during intraluminal pressurization.

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Three-dimensional analysis of the thoracic aorta microscopic deformation during intraluminal pressurization.

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