Assessment of the sequential change of the masseter muscle by clenching: A quantitative analysis of T1, T2, and the signal intensity of the balanced steady-state free precession
Assessment of the sequential change of the masseter muscle by clenching: A quantitative analysis of T1, T2, and the signal intensity of the balanced steady-state free precession
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DOI：
10.3109/02841851003702180
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发表时间：
2010-06
期刊：
影响因子：
1.3
通讯作者：
T. Chikui;T. Shiraishi;K. Tokumori;Daisuke Inatomi;M. Hatakenaka;K. Yuasa;K. Yoshiura
中科院分区：
文献类型：
--
作者：
T. Chikui;T. Shiraishi;K. Tokumori;Daisuke Inatomi;M. Hatakenaka;K. Yuasa;K. Yoshiura
背景：咬牙时持续的肌肉收缩被认为是导致某些颞下颌关节紊乱病的原因。然而，到目前为止，还没有报道通过磁共振成像（MRI）来评估紧咬对咀嚼肌的影响。目的：目的：研究最大随意收缩时的紧咬对咬肌平衡快场回波（B FFE）T1、T2和信号强度（SI）的影响。材料和方法：共有11名志愿者参加。T2测量采用多回波自旋回波回波回波平面回波成像，T1测量采用多激发Look-stimulus序列。Look-T1序列已被用于快速T1映射，并且该方法已被应用于各种组织的成像。此外，由于高时间分辨率，使用了B FFE。这三个序列持续10分钟，参与者被指示在数据采集开始后从60秒到80秒握紧。T2、T1和SI与咬紧前的值相比进行了标准化。结果：T2在紧咬时下降，这反映了由于机械压力导致的组织灌注减少。咬合后迅速增加（峰值1.11 ± 0.03，峰值时间16.8 ± 7.6s），与反应性充血相对应，随后逐渐恢复至初始值（半周期2.22 ± 0.84min）。B FFE的SI变化是三相的，与T2紧握的变化相似。T1增加后，停止紧握，后来逐渐下降，在恢复期。T1与T2的变化有显著性差异，峰值较低（1.04 ± 0.02），峰值时间较晚（36.0 ± 28.0 s），半衰期较长（4.76 ± 3.40 min）（P分别<0.0001，0.0066，0.02）。结论：T2变化呈三相性，主要反映组织灌注情况。
Background: The persistent muscle contractions during clenching are thought to cause some temporomandibular disorders. However, no report has so far evaluated the effect of clenching on the masticatory muscles by magnetic resonance imaging (MRI). Purpose: To investigate the effect of clenching with maximum voluntary contraction on the T1, T2, and signal intensity (SI) of the balanced fast field-echo (b FFE) of the masseter muscle. Material and Methods: A total of 11 volunteers participated. Multi-echo spin-echo echo-planar imaging was used for T2 measurements, and multi-shot Look-Locker sequence for T1 measurements. The Look-Locker sequence has been used for fast T1 mapping and this method has been applied for the imaging of various tissues. In addition, the b FFE was used due to the high temporal resolution. These three sequences lasted for 10 min and the participants were instructed to clench from 60 s to 80 s after the start of the data acquisition. T2, T1, and SI were normalized compared to pre-clenching values. Results: T2 decreased by clenching, which reflected a decrease of tissue perfusion due to the mechanical pressure. It increased rapidly after the clenching (peak value, 1.11±0.03; peak time, 16.8±7.6 s after the clenching), which corresponded to the reactive hyperemia and later, it gradually returned to the initial values (half period, 2.22±0.84 min). The change in the SI of the b FFE was triphasic and similar to that of T2 clenching. T1 increased after the cessation of the clenching and later gradually decreased during the recovery periods. However, the change of T1 was quite different from that of T2, with a lower peak value (1.04±0.02), a later peak time (36.0±28.0 s), and a longer half period (4.76±3.40 min) (P<0.0001, 0.0066, 0.02, respectively). Conclusion: The change in T2 was triphasic and we considered that it predominantly reflected the tissue perfusion.