All scans were obtained using a 1.5T MRI system, using a transmit-receive coil (Magnetom Sonata; Siemens Medical Solutions, Erlangen, Germany) (maximum amplitude: 40 mT m -1 ; slew rate: 200 mT m -1 msec -1 ). For imaging, we used a fast low-angle shot (FLASH) protocol. The parameters used were: TR, 4.3 ms; TE, 1.7 ms; flip angle, 25°; field of view (FOV), 320 × 200 mm; matrix size, 512 × 320; and slice thickness, 1 mm. The source images were made available for analysis on a workstation that allowed interactive multiplanar reformatting of the data sets.