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 progressively more anatomic details of the inner ear and is playing an important role in the diagnostic evaluation of patients with sensorineural hearing loss. We present a three-dimensional (3D) segment-interleaved, 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 sequence uses gradient moment nulling over TR and segmented interleaved acquisition of multiple data sets with different radiofrequency (RF) phase-cycling schemes. Combination of data from multiple acquisitions by averaging and maximum intensity projection were compared. Images of phantoms and in vivo inner ears were obtained with both full and fractional echoes and compared with other high resolution techniques such as three-dimensional gradient-echo and two-dimensional (2D) and three-dimensional fast spin-echo (FSE) sequences. The new sequence achieves improved signal-to-noise ratio (SNR) and spatial resolution resulting in improved depiction of inner ear structures.