Fig. 2

MRA (MIP) in upper raw (a-d), BPAS in middle raw (e-h) and BPAS zooming in the affected PICA in lower raw (i-l). From the left column to the right column, the data of 2 weeks after the onset (a, e and i), 1 month (b, f and j), 2 months (c, g and k) and 4 months (d, h and l) are lined. Chronological changes of PICA inner diameter (MIP) and outer diameter (BPAS) are shown. MIPs show that the inner diameter of the right PICA grows maximally on the 14th day and are gradually downsizing. These MRI findings show the inner diameter reduction precedes the outer diameter’s shrinkage