Evaluation and verification of patient-specific modelling of type B aortic dissection

2021 ◽  
pp. 105053
Author(s):  
Chlöe H. Armour ◽  
Baolei Guo ◽  
Simone Saitta ◽  
Selene Pirola ◽  
Yifan Liu ◽  
...  
Keyword(s):  
Aortic Dissection ◽  
Patient Specific ◽  
Type B ◽  
Type B Aortic Dissection

Investigation of three-dimensional printing materials for printing aorta model replicating Type B aortic dissection

2021 ◽  
Vol 17 ◽  
Author(s):  
Chia-An Wu ◽  
Andrew Squelch ◽  
Zhonghua Sun
Keyword(s):  
3D Printing ◽  
Aortic Dissection ◽  
Three Dimensional ◽  
Ct Images ◽  
Patient Specific ◽  
Type B ◽  
Type B Aortic Dissection ◽  
Ct Attenuation ◽  
Significant Difference ◽  
3D Printed

Aim: To determine a printing material that has both elastic property and radiology equivalence close to real aorta for simulation of endovascular stent graft repair of aortic dissection. Background: With the rapid development of three-dimensional (3D) printing technology, a patient-specific 3D printed model is able to help surgeons to make better treatment plan for Type B aortic dissection patients. However, the radiological properties of most 3D printing materials have not been well characterized. This study aims to investigate the appropriate materials for printing human aorta with mechanical and radiological properties similar to the real aortic computed tomography (CT) attenuation. Objective: Quantitative assessment of CT attenuation of different materials used in 3D printed models of aortic dissection for developing patient-specific 3D printed aorta models to simulate type B aortic dissection. Method: A 25-mm length of aorta model was segmented from a patient’s image dataset with diagnosis of type B aortic dissection. Four different elastic commercial 3D printing materials, namely Agilus A40 and A50, Visijet CE-NT A30 and A70 were selected and printed with different hardness. Totally four models were printed out and conducted CT scanned twice on a 192-slice CT scanner using the standard aortic CT angiography protocol, with and without contrast inside the lumen.Five reference points with region of interest (ROI) of 1.77 mm2 were selected at the aortic wall and intimal flap and their Hounsfield units (HU) were measured and compared with the CT attenuation of original CT images. The comparison between the patient’s aorta and models was performed through a paired-sample t-test to determine if there is any significant difference. Result: The mean CT attenuation of aortic wall of the original CT images was 80.7 HU. Analysis of images without using contrast medium showed that the material of Agilus A50 produced the mean CT attenuation of 82.6 HU, which is similar to that of original CT images. The CT attenuation measured at images acquired with other three materials was significantly lower than that of original images (p<0.05). After adding contrast medium, Visijet CE-NT A30 had an average CT attenuation of 90.6 HU, which is close to that of the original images with statistically significant difference (p>0.05). In contrast, the CT attenuation measured at images acquired with other three materials (Agilus A40, A50 and Visiject CE-NT A70) was 129 HU, 135 HU and 129.6 HU, respectively, which is significantly higher than that of original CT images (p<0.05). Conclusion: Both Visijet CE-NT and Agilus have tensile strength and elongation close to real patient’s tissue properties producing similar CT attenuation. Visijet CE-NT A30 is considered the appropriate material for printing aorta to simulate contrast-enhanced CT imaging of type B aortic dissection. Due to lack of body phantom in the experiments, further research with simulation of realistic anatomical body environment should be conducted.

scholarly journals Patient-specific simulation of stent-graft deployment in type B aortic dissection: model development and validation

2021 ◽  
Author(s):  
Xiaoxin Kan ◽  
Tao Ma ◽  
Jing Lin ◽  
Lu Wang ◽  
Zhihui Dong ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Aortic Dissection ◽  
Stent Graft ◽  
Aortic Wall ◽  
Computational Simulation ◽  
Model Complexity ◽  
Patient Specific ◽  
Uniaxial Tensile ◽  
Type B ◽  
Type B Aortic Dissection

AbstractThoracic endovascular aortic repair (TEVAR) has been accepted as the mainstream treatment for type B aortic dissection, but post-TEVAR biomechanical-related complications are still a major drawback. Unfortunately, the stent-graft (SG) configuration after implantation and biomechanical interactions between the SG and local aorta are usually unknown prior to a TEVAR procedure. The ability to obtain such information via personalised computational simulation would greatly assist clinicians in pre-surgical planning. In this study, a virtual SG deployment simulation framework was developed for the treatment for a complicated aortic dissection case. It incorporates patient-specific anatomical information based on pre-TEVAR CT angiographic images, details of the SG design and the mechanical properties of the stent wire, graft and dissected aorta. Hyperelastic material parameters for the aortic wall were determined based on uniaxial tensile testing performed on aortic tissue samples taken from type B aortic dissection patients. Pre-stress conditions of the aortic wall and the action of blood pressure were also accounted for. The simulated post-TEVAR configuration was compared with follow-up CT scans, demonstrating good agreement with mean deviations of 5.8% in local open area and 4.6 mm in stent strut position. Deployment of the SG increased the maximum principal stress by 24.30 kPa in the narrowed true lumen but reduced the stress by 31.38 kPa in the entry tear region where there was an aneurysmal expansion. Comparisons of simulation results with different levels of model complexity suggested that pre-stress of the aortic wall and blood pressure inside the SG should be included in order to accurately predict the deformation of the deployed SG.

scholarly journals The influence of inlet velocity profile on predicted flow in type B aortic dissection

2020 ◽  
Author(s):  
Chlöe Harriet Armour ◽  
Baolei Guo ◽  
Selene Pirola ◽  
Simone Saitta ◽  
Yifan Liu ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Aortic Dissection ◽  
Patient Specific ◽  
Type B ◽  
Flow Waveform ◽  
Type B Aortic Dissection ◽  
Specific Data ◽  
Inlet Velocity ◽  
Wall Shear

Abstract In order for computational fluid dynamics to provide quantitative parameters to aid in the clinical assessment of type B aortic dissection, the results must accurately mimic the hemodynamic environment within the aorta. The choice of inlet velocity profile (IVP) therefore is crucial; however, idealised profiles are often adopted, and the effect of IVP on hemodynamics in a dissected aorta is unclear. This study examined two scenarios with respect to the influence of IVP—using (a) patient-specific data in the form of a three-directional (3D), through-plane (TP) or flat IVP; and (b) non-patient-specific flow waveform. The results obtained from nine simulations using patient-specific data showed that all forms of IVP were able to reproduce global flow patterns as observed with 4D flow magnetic resonance imaging. Differences in maximum velocity and time-averaged wall shear stress near the primary entry tear were up to 3% and 6%, respectively, while pressure differences across the true and false lumen differed by up to 6%. More notable variations were found in regions of low wall shear stress when the primary entry tear was close to the left subclavian artery. The results obtained with non-patient-specific waveforms were markedly different. Throughout the aorta, a 25% reduction in stroke volume resulted in up to 28% and 35% reduction in velocity and wall shear stress, respectively, while the shape of flow waveform had a profound influence on the predicted pressure. The results of this study suggest that 3D, TP and flat IVPs all yield reasonably similar velocity and time-averaged wall shear stress results, but TP IVPs should be used where possible for better prediction of pressure. In the absence of patient-specific velocity data, effort should be made to acquire patient’s stroke volume and adjust the applied IVP accordingly.

scholarly journals Optimization of Computed Tomography Angiography Protocols for Follow-Up Type B Aortic Dissection Patients by Using 3D Printed Model

2021 ◽  
Vol 11 (15) ◽  
pp. 6844
Author(s):  
Chia-An Wu ◽  
Andrew Squelch ◽  
Shirley Jansen ◽  
Zhonghua Sun
Keyword(s):  
Computed Tomography ◽  
Image Quality ◽  
Aortic Dissection ◽  
Signal To Noise Ratio ◽  
Three Dimensional ◽  
Ct Scans ◽  
Patient Specific ◽  
Type B ◽  
Type B Aortic Dissection ◽  
3D Printed

Thoracic endovascular aortic repair (TEVAR) is a life-saving therapy for type B aortic dissection (TBAD). However, surveillance computed tomography (CT) scans in post-TEVAR patients are associated with high radiation dose, thus resulting in potential risk of radiation-induced malignancy. In this study, we developed a patient-specific three-dimensional (3D) printed phantom with stent grafts in situ, then scanned the phantom with different CT protocols to determine the optimal scanning parameters for post-treatment patients. The CT scans were conducted with different kVp and pitch values (80, 100, 120 kVp and pitch of 1.2, 1.5, 2.0, 2.5), resulting in a total of 12 datasets. Signal-to-noise ratio (SNR) was measured to determine and compare the image quality between different datasets. Results showed no significant differences in SNR between different kVp when the pitch value was 1.2. At low pitch values, a decrease in kVp from 120 to 80 led to a significant effective dose reduction by more than 20%. SNR decreased by 30% when pitch was increased from 1.2 to 2.5 at 80 kVp, and 20% at 120 kVp. In contrast, there was only a 3.9% decrease in SNR when kVp was reduced from 120 to 80 at pitch 1.2, and 15.9% at pitch 2.5. High pitch with 100 kVp can effectively reduce the dose while maintaining image quality.

scholarly journals A patient-specific study of type-B aortic dissection: evaluation of true-false lumen blood exchange

2013 ◽  
Vol 12 (1) ◽  
pp. 65 ◽  
Author(s):  
Duanduan Chen ◽  
Matthias Müller-Eschner ◽  
Hendrik von Tengg-Kobligk ◽  
David Barber ◽  
Dittmar Böckler ◽  
...  
Keyword(s):  
Aortic Dissection ◽  
False Lumen ◽  
Patient Specific ◽  
Type B ◽  
Type B Aortic Dissection ◽  
Specific Study ◽  
Blood Exchange ◽  
True False

scholarly journals THE IMPACT OF THE NUMBER OF TEARS IN PATIENT-SPECIFIC STANFORD TYPE B AORTIC DISSECTING ANEURYSM: CFD SIMULATION

2014 ◽  
Vol 14 (02) ◽  
pp. 1450017 ◽  
Author(s):  
WAN NAIMAH WAN AB NAIM ◽  
POO BALAN GANESAN ◽  
ZHONGHUA SUN ◽  
KAHAR OSMAN ◽  
EINLY LIM
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Aortic Dissection ◽  
False Lumen ◽  
Patient Specific ◽  
Type B ◽  
Type B Aortic Dissection ◽  
Wall Shear ◽  
The Impact ◽  
Stanford Type B

It is believed that the progression of Stanford type B aortic dissection is closely associated with vascular geometry and hemodynamic parameters. The hemodynamic differences owing to the presence of greater than two tears have not been explored. The focus of the present study is to investigate the impact of an additional re-entry tear on the flow, pressure and wall shear stress distribution in the dissected aorta. A 3D aorta model with one entry and one re-entry tear was generated from computed tomography (CT) angiographic images of a patient with Stanford Type B aortic dissection. To investigate the hemodynamic effect of more than two tear locations, an additional circular re-entry tear was added 24 mm above the original re-entry tear. Our simulation results showed that the presence of an additional re-entry tear provided an extra return path for blood back to the true lumen during systole, and an extra outflow path into the false lumen during diastole. The presence of this additional path led to a decrease in the false lumen pressure, particularly at the distal region. Meanwhile, the presence of this additional tear causes no significant difference on the time average wall shear stress (TAWSS) distribution except at regions adjacent to re-entry tear 2. Moderate and concentrated TAWSS was observed at the bottom region of this additional tear which may lead to further extension of the tear distally.

scholarly journals The Effect of Beta-Blockers on Hemodynamic Parameters in Patient-Specific Blood Flow Simulations of Type-B Aortic Dissection: An Virtual Study

2021 ◽  
Author(s):  
Mohammad Amin Abazari ◽  
Deniz Rafieianzab ◽  
M. Soltani ◽  
Mona Alimohammadi
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Aortic Dissection ◽  
Antihypertensive Drugs ◽  
Patient Specific ◽  
Hemodynamic Parameters ◽  
Type B ◽  
Type B Aortic Dissection ◽  
Wall Shear

Abstract Type-B aortic dissection (AD) is one of the greatest complex and fatal conditions with co-occurring disorders, challenging to treat. The initial treatment for patients presenting with AD is medical intervention to stabilize the condition. In the present study, a patient-specific geometry of type-B AD is generated from computed tomography images, and a three-element Windkessel lumped parameter model is implemented at the outlets to realistic boundary conditions. According to the physiological response of the antihypertensive drugs in the reduction of aortic blood flow and heart rate, three case studies with different heart rates have been created. Hemodynamic distributions including wall shear stress indicators, velocity and pressure are investigated and compared in each model. Results show that there is a considerable reduction in pressure furthermore, time-averaged wall shear stress (TAWSS) values decreased by 25% and 30%, respectively. Main goal is to critically analysis the use of biomechanical and computational simulation tools to measure hemodynamic parameters in the absence and presence of antihypertensive drugs. It would be of significant use to clinicians to improve diagnostic and treatment planning.

scholarly journals Patient-Specific Virtual Stent-Graft Deployment for Type B Aortic Dissection: A Pilot Study of the Impact of Stent-Graft Length

2021 ◽  
Vol 12 ◽  
Author(s):  
Xiaoxin Kan ◽  
Tao Ma ◽  
Zhihui Dong ◽  
Xiao Yun Xu
Keyword(s):  
Pilot Study ◽  
Aortic Dissection ◽  
Stent Graft ◽  
Von Mises Stress ◽  
Patient Specific ◽  
Type B ◽  
Type B Aortic Dissection ◽  
Landing Zone ◽  
Von Mises ◽  
The Impact

Thoracic endovascular aortic repair (TEVAR) has been accepted as a standard treatment option for complicated type B aortic dissection. Distal stent-graft-induced new entry (SINE) is recognised as one of the main post-TEVAR complications, which can lead to fatal prognosis. Previous retrospective cohort studies suggested that short stent-graft (SG) length (&lt;165 mm) might correlate with increased risk of distal SINE. However, the influence of SG length on changes in local biomechanical conditions before and after TEVAR is unknown. In this paper, we aim to address this issue using a virtual SG deployment simulation model developed for application in type B aortic dissection. Our model incorporates detailed SG design and hyperelastic behaviour of the aortic wall. By making use of patient-specific geometry reconstructed from pre-TEVAR computed tomography angiography (CTA) scan, our model can predict post-TEVAR SG configuration and wall stress. Virtual SG deployment simulations were performed on a patient who underwent TEVAR with a short SG (158 mm in length), mimicking the actual clinical procedure. Further simulations were carried out on the same patient geometry but with different SG lengths (183 mm and 208 mm) in order to evaluate the effect of SG length on changes in local stress in the treated aorta. Comparisons of simulation results for different SG lengths showed the location of maximum stress varied with the SG length. With the short SG (deployed in the patient), the maximum von Mises stress of 238.9 kPa was found on the intimal flap at the distal landing zone where SINE was identified at 3-month follow-up. Increasing the SG length caused the maximum von Mises stress to move away from the distal landing zone where stress values were reduced by approximately 17% with the medium-length SG and by 60% with the long SG. This pilot study demonstrates the potential of using the virtual SG deployment model as a pre-surgical planning tool to help select the most appropriate SG length for individual patients.

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