The second aim of our study is 1) to provide the sensibility of our MRI protocol to estimate local and regional heterogeneity in aortic functional parameters (distensibility, compliance and PWV) 2) to evaluate the predictive value of these regional aortic parameters assessed by MRI to diagnose and to stratify the aortopathy related to presymptomatic Marfan patients and to bicuspid aortic valve in young adults, in comparison to carotids-femoral pulse wave velocity estimation by applanation tonometry.