MR visualization of the inner ear structures: comparison of 1.5 Tesla and 3 Tesla images.
OBJECTIVE
To compare high resolution MRI examinations of inner ear structures at 1.5 T and at 3 T.


METHODS
Temporal bones were measured bilaterally in 3 healthy volunteers in a 1.5 T and in a 3 T MR-scanner using the respective one channel head coil (quadrature detection) of the manufacturer. The same steady-state gradient echo sequence (3D-CISS) was employed at a voxel size of 0.4 x 0.4 x 0.4 mm(3). The signal-to-noise ratio (SNR) was determined quantitatively.


RESULTS
An SNR of 8 could be achieved for the measurements at 3 T in 7:37 min. The SNR at 3 T was, on average, a factor of 1.34 higher than that at 1.5 T despite the fact that the excitation angle had to be drastically reduced (alpha = 42 degrees instead of alpha = 70 degrees at 1.5 T) due to the limit of the specific absorption rate (SAR).


CONCLUSIONS
The MR representation of the inner ear is clearly improved at 3 T. To obtain the same SNR at 1.5 T approximately the double measuring time would be required, connected with reduced patient comfort and an increased risk for a displacement of the head during the high resolution measurement.
Graf
H
H
Sektion für Experimentelle Radiologie, Eberhard-Karls-Universität Tübingen, Tuebingen Germany. hansjoerg.graf@med.uni-tuebingen.de
Schick
F
F
Claussen
C D
CD
Seemann
M D
MD
D003051:Cochlea / Q000033:anatomy & histology; D007758:Ear, Inner / Q000033:anatomy & histology*; D006801:Humans; D021621:Imaging, Three-Dimensional; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods; D010865:Pilot Projects; D012665:Semicircular Canals / Q000033:anatomy & histology; D013701:Temporal Bone / Q000033:anatomy & histology