A SEGMENT-INTERLEAVED MOTION-COMPENSATED ACQUISITION IN THE STEADY-STATE (SIMCAST) TECHNIQUE FOR HIGH-RESOLUTION IMAGING OF THE INNER-EAR

MRI, with ever-increasing spatial resolution, recently has depicted pr ogressively more anatomic details of the inner ear and is playing an i mportant role in the diagnostic evaluation of patients with sensorineu ral hearing loss. We present a three-dimensional (3D) segment-interlea ved, motion-compensated acquisition in steady state (SIMCAST) sequence that allows further increase in spatial resolution in reasonable scan times minimizing artifacts due to susceptibility and motion. The sequ ence uses gradient moment nulling over TR and segmented interleaved ac quisition of multiple data sets with different radiofrequency (RF) pha se-cycling schemes. Combination of data from multiple acquisitions by averaging and maximum intensity projection were compared. Images of ph antoms and in vivo inner ears were obtained with both full and fractio nal echoes and compared with other high resolution techniques such as three-dimensional gradient-echo and two-dimensional (2D) and three-dim ensional fast spin-echo (FSE) sequences. The new sequence achieves imp roved signal-to-noise ratio (SNR) and spatial resolution resulting in improved depiction of inner ear structures.