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

Abstract

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<or=0.05). The animals were euthanized after 3 months of hypertension 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 elastin 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.