FIG 3. Tagged MR images and data processed with PIV software during the diastolic phase. Row A, Six tagged MR images, (1)–(6), were obtained with an interval of 9 milliseconds during the diastolic phase. In the aneurysm replica, counterclockwise rotation of the tag lines is observed. The quantitative velocity is not known; however, we can estimate the hemodynamics in the aneurysm. The tag lines gradually disappear due to the longitudinal relaxation of the spin in the flowing fluid and due to the mixture of the spin. Rows B–D, Flow-vector (row B), vorticity (row C), and shear-strain (row D) images were processed with the PIV software by using the data of tagged MR images. Each image—a, b, c, d, and e—was obtained from the following datasets, respectively: (1) and (2), (2) and (3), (3) and (4), (4) and (5), and (5) and (6). The aneurysm is displayed in the same orientation as in Figure 1A. The flow-vector images reveal the flow vector (arrowheads) of the flowing fluid at each location in the replica every 9 ms. We could measure the quantitative velocity and the direction of flowing fluid. The maximum flow was 2.2 cm/s. Vorticity and shear-strain images are shown in gray scale. In the scalar legends depicted, gray at the midpoint means no vorticity or shear strain. During the diastolic phase, the absolute value of vorticity and shear strain seem to be low, according to the color shown on the images.