Tokyo Medical and Dental University, Japan.
Angle Orthod. 2011 Mar;81(2):237-44. doi: 10.2319/060210-301.1.
To use an accurate method of tooth visualization in magnetic resonance imaging (MRI) movie for the observation of spatio-temporal relationships among articulators.
The subjects were two volunteers. Each subject repeated a vowel-consonant-vowel syllable (ie, /asa/; /ata/), and the run was measured using a gradient echo sequence. A custom-made clear retainer filled with the jelly form of ferric ammonium citrate was then fit onto the dental arch, and a T1-weighted turbo-spin-echo sequence was taken. Landmarks were used for superimposition of the incisor boundary onto sequential images of MRI movie. Tracings were conducted to observe the spatio-temporal relationships among articulators.
The incisor boundary was clearly visible in the magnetic resonance images. After superimposition, the contact distance of the tongue to palate/incisor was found to be longer during /t/-articulation than during /s/-articulation. There were prominent differences in images with and without tooth superimposition in the front oral cavity.
The method could distinctly extract a tooth boundary in MRI. Detailed configurational relationships between the tongue and tooth were observed during the production of a fricative and a plosive in MRI movie using this method.
使用磁共振成像(MRI)电影中精确的牙齿可视化方法来观察下颌运动各部件之间的时空关系。
研究对象为 2 名志愿者。每位志愿者重复发一个元音-辅音-元音音节(即/asa/、/ata/),并采用梯度回波序列进行测量。然后将一个特制的透明保持器装满柠檬酸铁铵凝胶,贴合在牙弓上,再进行 T1 加权涡轮自旋回波序列扫描。使用标志点将切牙边界叠加到 MRI 电影的连续图像上。进行追踪以观察下颌运动各部件之间的时空关系。
在磁共振图像上可以清晰地看到切牙边界。叠加后发现,在/t/-发音时,舌与上腭/切牙的接触距离比在/s/-发音时更长。在前口腔中,有和没有牙齿叠加的图像有明显差异。
该方法可以在 MRI 中明显提取牙齿边界。使用该方法可以在 MRI 电影中观察到摩擦音和爆破音发音时舌与牙齿之间的详细结构关系。