Gäbler Katrin, Brühschwein A, Loderstedt S, Oechtering G, Ludewig E
Klinik für Kleintiere, der Universität Leipzig, 04103 Leipzig.
Tierarztl Prax Ausg K Kleintiere Heimtiere. 2011;39(2):79-88.
In magnetic resonance imaging (MRI) the image quality is considerably affected by the coil used, particularly when small structures are examined. The purpose of this study was to determine which coil provides the best scanning results for imaging of the temporomandibular joint (TMJ) of dogs and cats.
MRI investigations were performed using a standard human knee coil and an 8-cm-diameter surface coil with a low-field MRI-system (field strength 0.5 T). TMJs of two dogs and two cats were examined. The scan protocol consisted of T1-weighted spin echo (T1W/SE), T2-weighted turbo spin echo (T2W/TSE), a proton density-weighted sequence (PDW) (slice thickness: 3 mm each), and gradient echo sequences (slice thickness: 1-1.5 mm) in the sagittal plane. Three observers independently compared the features "contrast resolution", "bone structure", "spatial resolution", and "signal-to-noise ratio" (SNR) using a 5-point scale. Investigators were blinded with respect to the coils used.
Approximately 50% of the images obtained by the use of the surface coil were rated superior in comparison with the knee coil in terms of the features "contrast resolution", "bone structure", and "spatial resolution". In approximately 50% of the MRI-images no differences in the ratings were seen. With respect to the criterion "signal-to-noise ratio" 90% of the images acquired with the surface coil were rated better. In 5% of the images an identical quality was recorded. The surface coil proved to be superior both in dogs and cats.
Display quality of small structures of the TMJ is dependent on the spatial resolution of the MR images. Therefore, a dedicated coil and a small field of view (FOV) should be used. Results reveal that low-field MRI is able to display subtle anatomic structures of the TMJ in dogs and cats. In principle, the results can be transmitted to other MRI-systems. However, to generate valid scan protocols it is necessary to adapt scan parameters and coil selection specifically.
在磁共振成像（MRI）中，图像质量会受到所用线圈的显著影响，尤其是在检查小结构时。本研究的目的是确定哪种线圈能为犬猫颞下颌关节（TMJ）成像提供最佳扫描结果。
使用标准人体膝关节线圈和一个直径8厘米的表面线圈，通过低场MRI系统（场强0.5T）进行MRI检查。对两只犬和两只猫的颞下颌关节进行了检查。扫描方案包括矢状面的T1加权自旋回波（T1W/SE）、T2加权快速自旋回波（T2W/TSE）、质子密度加权序列（PDW）（层厚均为3毫米）以及梯度回波序列（层厚为1 - 1.5毫米）。三名观察者使用5分制独立比较“对比度分辨率”“骨结构”“空间分辨率”和“信噪比”（SNR）等特征。研究人员对所使用的线圈不知情。
就“对比度分辨率”“骨结构”和“空间分辨率”特征而言，使用表面线圈获得的图像中约50%被评为优于膝关节线圈。在约50%的MRI图像中，评级未见差异。关于“信噪比”标准，使用表面线圈采集的图像中有90%被评为更好。在5%的图像中记录到相同的质量。表面线圈在犬和猫中均被证明更优。
TMJ小结构的显示质量取决于MR图像的空间分辨率。因此，应使用专用线圈和小视野（FOV）。结果表明，低场MRI能够显示犬猫TMJ的细微解剖结构。原则上，这些结果可应用于其他MRI系统。然而，为生成有效的扫描方案，有必要专门调整扫描参数和线圈选择。
