Non-contrast magnetic resonance angiography and computational fluid dynamic analysis of renal artery for renovascular hypertension

Renovascular hypertension is caused by renal artery stenosis (RAS) . The relationship . The relationship among RAS, hypertension, and renal function varies from patient to patient is difficult to assess, but the severity of association increases risks for patient. An accurate, reliable and non-invasive method to evaluate severity and hemodynamics of RAS is mandatory. MRA is a well-known method in the angiographic illustration of RAS in current clinical application. However, there exists limitation in its application, especially lack of capability in blood pressure measurement. On the other hand, the technology of the patient-specific computational fluid dynamics (CFD) is another novel technology to to enable quantitatively estimate vascular vascular hemodynamics. To date, there is no report no report to determine the RAS vascular hemodynamics using CFD. The objective of this study is to establish a non-invasive methodology for morphological and hemodynamic assessment of RAS. The hypothesis is that there exists an internal relationship between hemodynamic change and morphological transformation of renal arteries. Thus, evaluating the hemodynamic change of different grade stenotic renal arteries can reflect on the morphologic status. Non-contrast MRA was used in this thesis to assess the morphological status of renal arteries and CFD was used to calculate the hemodynamic parameters of various stenoses. Newly developed non-contrast MRA technique, named steady state free precession (SSFP) state free precession was investigated and assessed as an accurate method in visualization of renal artery. The results of CFD simulation demonstrated its potential ability for understanding the relationship between hemodynamics and morphology of renal artery stenosis. The application of CFD technology on modified renal artery stenosis improved prediction of the hemodynamics of renal artery after simulated percutaneous angioplasty and stenting. It was found that CFD simulation can provide useful information for patient stratification and strategy for further treatment decision, and it may also be able to support be able to support the clinical practice for intervention treatment of renal artery stenosis.