A 3T GE (DISCOVERY MR 750, GE Healthcare, Waukesha, WI, USA) and a 3T Siemens Trio MR scanner (Siemens Healthcare, Ehrlangen, Germany) will be used in this study. The multiple sequences will include 3D time of flight (TOF) MR angiography, 3D T1-weighted imaging, proton attenuation weighted imaging, magnetization-prepared rapid acquisition with gradient-echo sequence (MPRAGE), and contrast enhancement on T1-weighted imaging.