Graf H, Schick F, Claussen C D, Seemann M D
Sektion für Experimentelle Radiologie, Eberhard-Karls-Universität Tübingen, Tuebingen Germany.
Rofo. 2004 Jan;176(1):17-20. doi: 10.1055/s-2004-814672.
To compare high resolution MRI examinations of inner ear structures at 1.5 T and at 3 T.
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.
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).
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.
比较1.5T和3T条件下内耳结构的高分辨率MRI检查。
在1.5T和3T MR扫描仪中，使用制造商各自的单通道头部线圈（正交检测）对3名健康志愿者的双侧颞骨进行测量。采用相同的稳态梯度回波序列（3D-CISS），体素大小为0.4×0.4×0.4mm³。定量测定信噪比（SNR）。
在3T条件下，7分37秒的测量可实现8的SNR。尽管由于比吸收率（SAR）的限制，激发角必须大幅降低（1.5T时α = 70°，3T时α = 42°），但3T时的SNR平均比1.5T时高1.34倍。
3T时内耳的MR成像明显改善。在1.5T时要获得相同的SNR，大约需要两倍的测量时间，这会降低患者舒适度，并增加高分辨率测量期间头部移位的风险。
