Biomechanical Assessment Using MRI of Custom-Made Bovine Pericardial Tubes as Potential Aortic Replacements

Autologous materials for vessel replacement in infected fields have high morbidity and mortality rates. Custom-made bovine pericardial tubes (CMBPTs) offer a promising alternative with advantages such as reliability, strength, and availability. However, limited biomechanical data hinder predictions of in vivo performance. This study evaluates the physiological strain and distensibility of CMBPTs in vitro under simulated abdominal aortic flow using magnetic resonance imaging (MRI). A secondary objective is to compare strain and distensibility calculations using phase contrast (PC) and steady-state free precession (SSFP) MRI sequences.

Seven CMBPTs were tested under physiological aortic conditions with a pulsatile flow rate of 1650 mL/min using in vitro MRI. PC and SSFP sequences were employed, with PC estimating velocity and strain, while SSFP assessed strain separately. Image analysis was performed using QIR-MR software.

Strain was measured using magnitude images. The mean maximum cross-sectional areas were 419 ± 22.1 (PC) and 438.4 ± 24.3 mm² (SSFP), while minimum areas were 374.5 ± 21.1 and 397.6 ± 23.4 mm², respectively. The mean strain percentages were 12.1% ± 3.60% (PC) and 10.3% ± 3.20% (SSFP), with distensibility values of 1.5 ± 0.5 × 10^-3 and 1.3 ± 0.4 × 10^-3 mmHg^-1, respectively.

CMBPTs exhibit biomechanical properties similar to the abdominal aorta, suggesting potential for vascular applications. Both MRI sequences provided comparable results, supporting their reliability. Further research is needed to confirm long-term performance.