Phase-contrast MRI-based elastography technique detects early hypertensive changes in Ex vivo porcine aortic wall

Purpose: To measure the elastic properties of ex vivo porcine aortas in control and hypertensive groups using a phase contrast magnetic resonance imaging (MRI)-based elastography technique. Materials and Methods: Female domestic pigs were randomized to a normal control group (N; n = 5) or a renovascular hypertension group (HT; n = 5) for the duration of 3 months. Mean arterial pressure was significantly higher in the hypertension group than in the control group (173 ± 12 vs. 115 ± 11 mmHg, P £ 0.05). The animals were euthanized after 3 months ofhypertension and abdominal aortas harvested. The ex vivo aortic samples were then examined using a phase-contrast MRI-based elastography technique. Results: The Young's modulus-wall thickness product, a reflection of vascular stiffness, was significantly higher in the hypertension group than in the control group (0.571 ± 0.080 vs. 0.419 ± 0.026, P < 0.05). Histological analysis and staining confirmed increased intima-media thickness and collagen content in the hypertensive aorta, while elas-tin staining showed no difference. Conclusion: The current study shows that MR elastography offers a method to study the physiologic changes in the arterial wall secondary to early hypertension.