In Vivo MRI-based Parameters of Aortic Biomechanics Correlate with Aortic Tissue Properties Measured Ex Vivo
Presented During:
Thursday, April 25, 2024: 5:38PM - 7:00PM
Sheraton Times Square
Posted Room Name:
Central Park
Abstract No:
P0169
Submission Type:
Abstract Submission
Authors:
Jennifer Chung (1), Hijun Seo (2), Nitish Bhatt (3), Farshad Tajeddini (4), Maral Ouzounian (5), Kate Hanneman (6), Rifat Islam (2), Craig Simmons (2)
Institutions:
(1) Toronto General Hospital, Toronto, Ontario, (2) University of Toronto, Toronto, Ontario, (3) University of Toronto, Toronto, NA, (4) N/A, N/A, (5) Toronto General Hospital, Toronto, ON, (6) University of Toronto, Toronto, Canada
Submitting Author:
Jennifer Chung
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Toronto General Hospital
Toronto General Hospital
Co-Author(s):
Hijun Seo
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University of Toronto
University of Toronto
Nitish Bhatt
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University of Toronto
University of Toronto
Farshad Tajeddinisarvestani
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N/A
N/A
*Maral Ouzounian
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Toronto General Hospital
Toronto General Hospital
Kate Hanneman
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University of Toronto
University of Toronto
Rifat Islam
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University of Toronto
University of Toronto
Craig Simmons
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University of Toronto
University of Toronto
Presenting Author:
Jennifer Chung
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Toronto General Hospital
Toronto General Hospital
Abstract:
Objectives: Aortic biomechanics reflect material properties of aortic tissue including fragility in patients with ascending thoracic aortic aneurysms (ATAA). However, clinical translation requires robust methods for in vivo quantification of aorta biomechanics. This study validates, for the first time, in vivo MRI-based aortic biomechanical parameters against patient-specific ex vivo aortic biomechanical testing.
Methods: Preoperative MRI (including MR angiogram, 2D phase contrast and 4D flow sequences) was acquired in 17 patients with ATAA undergoing surgery and 4 healthy volunteers. In vivo aortic biomechanical parameters derived included strain, distensibility, compliance, arterial stiffness index (ASI), aortic pulse wave velocity (aPWV) and kinetic energy loss (KEL). Aortic tissue from ATAA patients was excised during surgery and ex vivo mechanical tests were performed to derive biomechanical properties including energy loss (effciency in performing the Windkessel function) and delamination strength (strength between tissue layers). Linear regression was used to compare the in vivo and ex vivo aortic biomechanical parameters.
Results: Strain, distensibility and compliance were not significantly different between aneurysm and control, and they also correlated poorly with ex vivo biomechanical parameters. In vivo ASI demonstrated a positive correlation with energy loss (R2 = 0.61, p<0.001), and a negative correlation with delamination strength (R2 = 0.53, p<0.011). In vivo aPWV was significantly lower in healthy controls compared to ATAA patients (p=0.01) and demonstrated a positive correlation with energy loss (R2 = 0.77, p<0.001), and a negative correlation with delamination strength (R2 = 0.52, p=0.002). In vivo KEL was significantly lower in healthy controls compared to ATAA patients (p<0.001) and demonstrated a positive correlation with energy loss (R2 = 0.31, p=0.04), and a negative correlation with delamination strength (R2 = 0.69, p<0.001).
Conclusions: MRI-based measurements of ASI, aPWV and KEL correlate strongly with ex vivo aortic biomechanical properties including energy loss and delamination strength. These imaging parameters are measurable in clinic to determine quality of aortic tissue. Future work includes multivariable analysis to improve accuracy of in vivo measurements of aortic biomechanics.
Methods: Preoperative MRI (including MR angiogram, 2D phase contrast and 4D flow sequences) was acquired in 17 patients with ATAA undergoing surgery and 4 healthy volunteers. In vivo aortic biomechanical parameters derived included strain, distensibility, compliance, arterial stiffness index (ASI), aortic pulse wave velocity (aPWV) and kinetic energy loss (KEL). Aortic tissue from ATAA patients was excised during surgery and ex vivo mechanical tests were performed to derive biomechanical properties including energy loss (effciency in performing the Windkessel function) and delamination strength (strength between tissue layers). Linear regression was used to compare the in vivo and ex vivo aortic biomechanical parameters.
Results: Strain, distensibility and compliance were not significantly different between aneurysm and control, and they also correlated poorly with ex vivo biomechanical parameters. In vivo ASI demonstrated a positive correlation with energy loss (R2 = 0.61, p<0.001), and a negative correlation with delamination strength (R2 = 0.53, p<0.011). In vivo aPWV was significantly lower in healthy controls compared to ATAA patients (p=0.01) and demonstrated a positive correlation with energy loss (R2 = 0.77, p<0.001), and a negative correlation with delamination strength (R2 = 0.52, p=0.002). In vivo KEL was significantly lower in healthy controls compared to ATAA patients (p<0.001) and demonstrated a positive correlation with energy loss (R2 = 0.31, p=0.04), and a negative correlation with delamination strength (R2 = 0.69, p<0.001).
Conclusions: MRI-based measurements of ASI, aPWV and KEL correlate strongly with ex vivo aortic biomechanical properties including energy loss and delamination strength. These imaging parameters are measurable in clinic to determine quality of aortic tissue. Future work includes multivariable analysis to improve accuracy of in vivo measurements of aortic biomechanics.
Aortic Symposium:
Ascending Aorta
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