Age-related changes in aortic 3D blood flow velocities and wall shear stress: Implications for the identification of altered hemodynamics in patients with aortic valve disease

PurposeTo investigate age-related changes in peak systolic aortic 3D velocity and wall shear stress (WSS) in healthy controls and to investigate the importance of age-matching for 3D mapping of abnormal aortic hemodynamics in bicuspid aortic valve disease (BAV). Materials and Methods4D flow MRI (fields strengths=1.5-3T; resolution=2.2-3.9x1.7-2.6x2.2-4.0mm(3); Venc=150-250cm/s; TE/TR/FA=2.3-2.8/4.7-5.4msec/7-15 degrees) was performed in 56 controls (age range: 19-78 years) and in two BAV patient groups each consisting of 10 subjects (group 1: 20-29 years, group 2: 52-57 years). Heat maps showing abnormal 3D velocity and WSS were created for the BAV patients by comparison with an age-matched and with an unmatched control group. The fraction of the aorta exposed to abnormal velocity/WSS was calculated relative to the total aortic volume/surface. ResultsSignificant inverse relationships between age and healthy velocity/WSS were found (R-2=0.32/0.39, P<0.001). For BAV group 1, abnormally elevated velocity/WSS was overestimated when compared with older controls (51-60 years) than when correctly age-matched (approximate to 2514% vs. approximate to 8 +/- 5%). For BAV group 2, abnormally decreased velocity/WSS was overestimated when compared with younger controls (21-30 years) than when correctly age-matched (approximate to 9 +/- 7% vs. 1 +/- 1%). ConclusionSignificant correlations exist between age and peak systolic velocity and WSS. Therefore, robust age-matching is important when creating abnormal 3D aortic velocity and WSS maps for patients with BAV. J. Magn. Reson. Imaging 2016;43:1239-1249.