scholarly journals Quantify patient-specific coronary material property and its impact on stress/strain calculations using in vivo IVUS data and 3D FSI models: a pilot study

2016 ◽  
Vol 16 (1) ◽  
pp. 333-344 ◽  
Author(s):  
Xiaoya Guo ◽  
Jian Zhu ◽  
Akiko Maehara ◽  
David Monoly ◽  
Habib Samady ◽  
...  
Keyword(s):  
Pilot Study ◽  
Material Property ◽  
Patient Specific ◽  
Stress Strain

scholarly journals Using In Vivo Cine and 3D Multi-Contrast MRI to Determine Human Atherosclerotic Carotid Artery Material Properties and Circumferential Shrinkage Rate and Their Impact on Stress/Strain Predictions

2012 ◽  
Vol 134 (1) ◽  
Author(s):  
Haofei Liu ◽  
Gador Canton ◽  
Chun Yuan ◽  
Chun Yang ◽  
Kristen Billiar ◽  
...  
Keyword(s):  
Carotid Artery ◽  
Material Properties ◽  
Shrinkage Rate ◽  
Patient Specific ◽  
Stress Strain ◽  
Lipid Core ◽  
Material Stiffness ◽  
Stiff Material ◽  
Parameter Values

In vivo magnetic resonance image (MRI)-based computational models have been introduced to calculate atherosclerotic plaque stress and strain conditions for possible rupture predictions. However, patient-specific vessel material properties are lacking in those models, which affects the accuracy of their stress/strain predictions. A noninvasive approach of combining in vivo Cine MRI, multicontrast 3D MRI, and computational modeling was introduced to quantify patient-specific carotid artery material properties and the circumferential shrinkage rate between vessel in vivo and zero-pressure geometries. In vivo Cine and 3D multicontrast MRI carotid plaque data were acquired from 12 patients after informed consent. For each patient, one nearly-circular slice and an iterative procedure were used to quantify parameter values in the modified Mooney-Rivlin model for the vessel and the vessel circumferential shrinkage rate. A sample artery slice with and without a lipid core and three material parameter sets representing stiff, median, and soft materials from our patient data were used to demonstrate the effect of material stiffness and circumferential shrinkage process on stress/strain predictions. Parameter values of the Mooney-Rivlin models for the 12 patients were quantified. The effective Young’s modulus (YM, unit: kPa) values varied from 137 (soft), 431 (median), to 1435 (stiff), and corresponding circumferential shrinkages were 32%, 12.6%, and 6%, respectively. Using the sample slice without the lipid core, the maximum plaque stress values (unit: kPa) from the soft and median materials were 153.3 and 96.2, which are 67.7% and 5% higher than that (91.4) from the stiff material, while the maximum plaque strain values from the soft and median materials were 0.71 and 0.293, which are about 700% and 230% higher than that (0.089) from the stiff material, respectively. Without circumferential shrinkages, the maximum plaque stress values (unit: kPa) from the soft, median, and stiff models were inflated to 330.7, 159.2, and 103.6, which were 116%, 65%, and 13% higher than those from models with proper shrinkage. The effective Young’s modulus from the 12 human carotid arteries studied varied from 137 kPa to 1435 kPa. The vessel circumferential shrinkage to the zero-pressure condition varied from 6% to 32%. The inclusion of proper shrinkage in models based on in vivo geometry is necessary to avoid over-estimating the stresses and strains by up 100%. Material stiffness had a greater impact on strain (up to 700%) than on stress (up to 70%) predictions. Accurate patient-specific material properties and circumferential shrinkage could considerably improve the accuracy of in vivo MRI-based computational stress/strain predictions.

scholarly journals Effects of Residual Stress, Axial Stretch, and Circumferential Shrinkage on Coronary Plaque Stress and Strain Calculations: A Modeling Study Using IVUS-Based Near-Idealized Geometries

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Liang Wang ◽  
Jian Zhu ◽  
Habib Samady ◽  
David Monoly ◽  
Jie Zheng ◽  
...  
Keyword(s):  
Residual Stress ◽  
Coronary Plaque ◽  
Model Construction ◽  
Patient Specific ◽  
Stress And Strain ◽  
Stress Strain ◽  
Axial Stretch ◽  
Stress Increase ◽  
Specific Material

Accurate stress and strain calculations are important for plaque progression and vulnerability assessment. Models based on in vivo data often need to form geometries with zero-stress/strain conditions. The goal of this paper is to use IVUS-based near-idealized geometries and introduce a three-step model construction process to include residual stress, axial shrinkage, and circumferential shrinkage and investigate their impacts on stress and strain calculations. In Vivo intravascular ultrasound (IVUS) data of human coronary were acquired for model construction. In Vivo IVUS movie data were acquired and used to determine patient-specific material parameter values. A three-step modeling procedure was used to make our model: (a) wrap the zero-stress vessel sector to obtain the residual stress; (b) stretch the vessel axially to its length in vivo; and (c) pressurize the vessel to recover its in vivo geometry. Eight models were constructed for our investigation. Wrapping led to reduced lumen and cap stress and increased out boundary stress. The model with axial stretch, circumferential shrink, but no wrapping overestimated lumen and cap stress by 182% and 448%, respectively. The model with wrapping, circumferential shrink, but no axial stretch predicted average lumen stress and cap stress as 0.76 kPa and −15 kPa. The same model with 10% axial stretch had 42.53 kPa lumen stress and 29.0 kPa cap stress, respectively. Skipping circumferential shrinkage leads to overexpansion of the vessel and incorrect stress/strain calculations. Vessel stiffness increase (100%) leads to 75% lumen stress increase and 102% cap stress increase.

Abstract 383: Patient-Specific Coronary Models Combining Intravascular Ultrasound and Optical Coherence Tomography Lead to More Accurate Plaque Cap Thickness and Stress/Strain Quantifications

2017 ◽  
Vol 37 (suppl_1) ◽  
Author(s):  
Xiaoya Guo ◽  
David Monoly ◽  
Chun Yang ◽  
Habib Samady ◽  
Jie Zheng ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Intravascular Ultrasound ◽  
Coronary Plaque ◽  
Patient Specific ◽  
Data Sets ◽  
Optical Coherence ◽  
Stress Strain ◽  
Data Set ◽  
The Impact

Accurate cap thickness and stress/strain quantifications are of fundamental importance for vulnerable plaque research. An innovative modeling approach combining intravascular ultrasound (IVUS) and optical coherence tomography (OCT) is introduced for more accurate patient-specific coronary morphology and stress/strain calculations. In vivo IVUS and OCT coronary plaque data were acquired from two patients with informed consent obtained. IVUS and OCT images were segmented, co-registered, and merged to form the IVUS+OCT data set, with OCT providing accurate cap thickness. Biplane angiography provided 3D vessel curvature. Due to IVUS resolution (150 μm), original virtual histology (VH) IVUS data often had lipid core exposed to lumen since it sets cap thickness as zero when cap thickness <150 μm. VH-IVUS data were processed with minimum cap thickness set as 50 and 180 μm to generate IVUS50 and IVUS180 data sets for modeling use. 3D fluid-structure interaction models based on IVUS+OCT, IVUS50 and IVUS180 data sets were constructed to investigate the impact of OCT cap thickness improvement on stress/strain calculations. Figure 1 is a brief summary of results from 27 slices with cap covering lipid cores from 2 patients. Mean cap thickness (unit: mm) from Patient 1 was 0.353 (OCT), 0.201 (IVUS50), and 0.329 (IVUS180), respectively. Patient 2 mean cap thickness was 0.320 (OCT), 0.224 (IVUS50), and 0.285 (IVUS180). IVUS50 underestimated cap thickness (27 slices) by 34.5%, compared to OCT cap values. IVUS50 overestimated mean cap stress (27 slices) by 45.8%, compared to OCT cap stress (96.4 vs. 66.1 kPa). IVUS50 maximum cap stress was 59.2% higher than that from IVUS+OCT model (564.2 vs. 354.5 kPa). Differences between IVUS and IVUS+OCT models for mean cap strain and flow shear stress were modest (cap strain: <12%; FSS <2%). Conclusion: IVUS+OCT data and models could provide more accurate cap thickness and stress/strain calculations which will serve as basis for plaque research.

Patient-Specific Echo-Based Left Ventricle Models for Active Contraction and Relaxation Using Different Zero-Load Diastole and Systole Geometries

2019 ◽  
Vol 16 (03) ◽  
pp. 1842014 ◽  
Author(s):  
Longling Fan ◽  
Jing Yao ◽  
Chun Yang ◽  
Di Xu ◽  
Dalin Tang
Keyword(s):  
Left Ventricle ◽  
Material Parameter ◽  
Patient Specific ◽  
Volume Data ◽  
Stress Strain ◽  
Young’S Moduli ◽  
Active Contraction ◽  
Contraction And Relaxation ◽  
Parameter Values

A new modeling approach using two different zero-load geometries (diastole and systole) was introduced to properly model active contraction and relaxation for more accurate stress/strain calculations. Ventricle diastole and systole material parameter values were also determined based on in vivo data. Echo-based computational two-layer left ventricle (LV) models using one zero-load geometry (1G) and two zero-load geometries (2G) were constructed. Material parameter values in Mooney–Rivlin models were also adjusted to match echo LV volume data. Effective Young’s moduli (YM) were calculated for ventricle materials for easy comparison. The 2G models may lead to more accurate ventricle stress/strain calculations and material parameter value estimations.

Bone Regeneration of Tibial Segmental Defect Using Isotropic-Pore Structures Hydroxyapatite/Alumina Bi-Layered Scaffold: In Vivo Pilot Study

2011 ◽  
Vol 21 (2) ◽  
pp. 159-167 ◽  
Author(s):  
Jun Sik Son ◽  
Jong Min Kim ◽  
Myungho Han ◽  
Seok Hwa Choi ◽  
Francis Y. Lee ◽  
...  
Keyword(s):  
Pilot Study ◽  
Bone Regeneration ◽  
Segmental Defect ◽  
Pore Structures

scholarly journals mRNA-Driven Generation of Transgene-Free Neural Stem Cells from Human Urine-Derived Cells

Cells ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1043 ◽  
Author(s):  
Phil Jun Kang ◽  
Daryeon Son ◽  
Tae Hee Ko ◽  
Wonjun Hong ◽  
Wonjin Yun ◽  
...  
Keyword(s):  
Stem Cells ◽  
Neural Stem Cells ◽  
Human Urine ◽  
Neurological Disorders ◽  
Therapeutic Potential ◽  
Embryonic Stem ◽  
Global Gene Expression ◽  
Patient Specific ◽  
Human Neural Stem Cells

Human neural stem cells (NSCs) hold enormous promise for neurological disorders, typically requiring their expandable and differentiable properties for regeneration of damaged neural tissues. Despite the therapeutic potential of induced NSCs (iNSCs), a major challenge for clinical feasibility is the presence of integrated transgenes in the host genome, contributing to the risk for undesired genotoxicity and tumorigenesis. Here, we describe the advanced transgene-free generation of iNSCs from human urine-derived cells (HUCs) by combining a cocktail of defined small molecules with self-replicable mRNA delivery. The established iNSCs were completely transgene-free in their cytosol and genome and further resembled human embryonic stem cell-derived NSCs in the morphology, biological characteristics, global gene expression, and potential to differentiate into functional neurons, astrocytes, and oligodendrocytes. Moreover, iNSC colonies were observed within eight days under optimized conditions, and no teratomas formed in vivo, implying the absence of pluripotent cells. This study proposes an approach to generate transplantable iNSCs that can be broadly applied for neurological disorders in a safe, efficient, and patient-specific manner.

In Vivo Measurements of Cranial Electrical Stimulation Using Stereotactic-EEG: A Pilot Study

2021 ◽  
Author(s):  
Minmin Wang ◽  
Shenghua Zhu ◽  
Haonan Guan ◽  
Hongjie Jiang ◽  
Jianmin Zhang ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Pilot Study ◽  
In Vivo Measurements

Design, Fabrication, and Accuracy of a Novel Noncovering Lock-Mechanism Bilateral Patient-Specific Drill Guide Template for Nondeformed and Deformed Thoracic Spines

2021 ◽  
pp. 155633162199633
Author(s):  
Mehran Ashouri-Sanjani ◽  
Shima Mohammadi-Moghadam ◽  
Parisa Azimi ◽  
Navid Arjmand
Keyword(s):  
Thoracic Spine ◽  
Sagittal Plane ◽  
Ct Scanning ◽  
Entry Point ◽  
In Vivo Studies ◽  
Patient Specific ◽  
Plane Angle ◽  
Severe Scoliosis ◽  
3D Printed

Background: Pedicle screw (PS) placement has been widely used in fusion surgeries on the thoracic spine. Achieving cost-effective yet accurate placements through nonradiation techniques remains challenging. Questions/Purposes: Novel noncovering lock-mechanism bilateral vertebra-specific drill guides for PS placement were designed/fabricated, and their accuracy for both nondeformed and deformed thoracic spines was tested. Methods: One nondeformed and 1 severe scoliosis human thoracic spine underwent computed tomographic (CT) scanning, and 2 identical proportions of each were 3-dimensional (3D) printed. Pedicle-specific optimal (no perforation) drilling trajectories were determined on the CT images based on the entry point/orientation/diameter/length of each PS. Vertebra-specific templates were designed and 3D printed, assuring minimal yet firm contacts with the vertebrae through a noncovering lock mechanism. One model of each patient was drilled using the freehand and one using the template guides (96 pedicle drillings). Postoperative CT scans from the models with the inserted PSs were obtained and superimposed on the preoperative planned models to evaluate deviations of the PSs. Results: All templates fitted their corresponding vertebra during the simulated operations. As compared with the freehand approach, PS placement deviations from their preplanned positions were significantly reduced: for the nonscoliosis model, from 2.4 to 0.9 mm for the entry point, 5.0° to 3.3° for the transverse plane angle, 7.1° to 2.2° for the sagittal plane angle, and 8.5° to 4.1° for the 3D angle, improving the success rate from 71.7% to 93.5%. Conclusions: These guides are valuable, as the accurate PS trajectory could be customized preoperatively to match the patients’ unique anatomy. In vivo studies will be required to validate this approach.

scholarly journals Creatine Supplementation for Patients with Inflammatory Bowl Diseases: A Scientific Rationale for a Clinical Trial

Nutrients ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 1429
Author(s):  
Theo Wallimann ◽  
Caroline H. T. Hall ◽  
Sean P. Colgan ◽  
Louise E. Glover
Keyword(s):  
Ulcerative Colitis ◽  
Clinical Trial ◽  
Crohn’S Disease ◽  
Pilot Study ◽  
Crohn's Disease ◽  
Single Case ◽  
Initial Period ◽  
Creatine Supplementation

Based on theoretical considerations, experimental data with cells in vitro, animal studies in vivo, as well as a single case pilot study with one colitis patient, a consolidated hypothesis can be put forward, stating that “oral supplementation with creatine monohydrate (Cr), a pleiotropic cellular energy precursor, is likely to be effective in inducing a favorable response and/or remission in patients with inflammatory bowel diseases (IBD), like ulcerative colitis and/or Crohn’s disease”. A current pilot clinical trial that incorporates the use of oral Cr at a dose of 2 × 7 g per day, over an initial period of 2 months in conjunction with ongoing therapies (NCT02463305) will be informative for the proposed larger, more long-term Cr supplementation study of 2 × 3–5 g of Cr per day for a time of 3–6 months. This strategy should be insightful to the potential for Cr in reducing or alleviating the symptoms of IBD. Supplementation with chemically pure Cr, a natural nutritional supplement, is well tolerated not only by healthy subjects, but also by patients with diverse neuromuscular diseases. If the outcome of such a clinical pilot study with Cr as monotherapy or in conjunction with metformin were positive, oral Cr supplementation could then be used in the future as potentially useful adjuvant therapeutic intervention for patients with IBD, preferably together with standard medication used for treating patients with chronic ulcerative colitis and/or Crohn’s disease.

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