Yuan-Hao Lee1, Wing P Chan2, Stephen J Swensen3. 1. Department of Radiology, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan. 2. Department of Radiology, Wan Fang Hospital, Taipei Medical University, Taipei, Taiwan; Department of Radiology, School of Medicine, Taipei Medical University, Taipei, Taiwan. Electronic address: wingchan@tmu.edu.tw. 3. Department of Radiology, Mayo Clinic, Rochester, Minnesota.