闭口状态下咀嚼肌 T2 值和表观弥散系数的评估。
Evaluation of T2 values and apparent diffusion coefficient of the masseter muscle by clenching.
机构信息
Section of Image Diagnosis, Department of Diagnostics and General Care, Fukuoka Dental College, Tamura 2-15-1, Sawara-ku, Fukuoka 814-0193, Japan.
出版信息
Dentomaxillofac Radiol. 2011 Jan;40(1):35-41. doi: 10.1259/dmfr/15607259.
OBJECTIVE
The aim of this study was to evaluate the changes in T2 values and apparent diffusion coefficient (ADC) in the masseter muscle by clenching in healthy volunteers.
METHODS
37 volunteers were enrolled in the study. We measured bite force using pressure-sensitive paper and a T2 map. The ADC map was obtained at rest, during clenching, immediately after and 5 min after clenching. The spin-echo sequence was used to calculate T2, and single-shot spin-echo echo planar imaging was used to calculate the ADC. The motion-probing gradients (MPGs) were applied separately along the posterior-to-anterior (PA), right-to-left (RL) and superior-to-inferior (SI) directions, with b values of 0, 300 and 600 s mm(-2) in each direction. ADC-PA, ADC-RL, and ADC-SI values were obtained, and we calculated the ADC-iso for the mean diffusivity.
RESULTS
There were no significant differences between the stronger and weaker sides of bite force before, during or 5 min after clenching for T2 and ADC. The bite force had little effect on these parameters; thus, we used the average of the two sides for the following analyses. Time course analysis of ADC-iso, ADC-PA, ADC-RL and ADC-SI demonstrated a marked increase after clenching and a rapid decrease immediately after clenching, although they did not completely return to the initial values; however, the change in ADC-RL was significantly greater than those in ADC-PA or ADC-SI (P<0.001 each). The changes in T2 were similar to those of ADC, although not as marked.
CONCLUSIONS
ADC (especially ADC-RL) was altered by contraction of the masseter muscle.
目的
本研究旨在评估健康志愿者咬牙时咬肌 T2 值和表观扩散系数（ADC）的变化。
方法
本研究纳入 37 名志愿者。我们使用压力敏感纸和 T2 图谱测量咬合力。在休息、咬牙、咬牙后即刻和咬牙后 5 分钟时，获得 ADC 图谱。使用自旋回波序列计算 T2，使用单次激发自旋回波平面成像计算 ADC。在各个方向上施加分别沿后前（PA）、右左（RL）和上下（SI）方向的运动探测梯度（MPG），每个方向的 b 值分别为 0、300 和 600 s mm(-2)。获得 ADC-PA、ADC-RL 和 ADC-SI 值，并计算平均弥散度的 ADC-iso。
结果
在咬牙前、咬牙中和咬牙后 5 分钟，T2 和 ADC 在咬合力较强和较弱的侧之间没有显著差异。咬合力对这些参数的影响较小；因此，我们在以下分析中使用两侧的平均值。ADC-iso、ADC-PA、ADC-RL 和 ADC-SI 的时间过程分析表明，咬牙后 ADC 明显增加，咬牙后即刻迅速下降，尽管它们并未完全恢复到初始值；然而，ADC-RL 的变化明显大于 ADC-PA 或 ADC-SI（均 P<0.001）。T2 的变化与 ADC 的变化相似，尽管不那么明显。
结论
咬肌收缩改变了 ADC（尤其是 ADC-RL）。
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