Faculty of Veterinary Medicine, Okayama University of Science, Imabari, Japan.
Open Vet J. 2020 Apr;10(1):68-73. doi: 10.4314/ovj.v10i1.11. Epub 2020 Mar 15.
In humans, visualization of the thoracic duct by magnetic resonance imaging (MRI) has been attempted, and recent advances have enabled clinicians to visualize the thoracic duct configuration in a less invasive manner. Moreover, MRI does not require contrast media, and it enables visualization of morphological details of the thoracic structures. In veterinary practice, the thoracic duct has not been visualized three dimensionally in MRI.
This study aimed to assess the performance of our magnetic resonance thoracic ductography (MRTD) technique to visualize the thoracic duct and the surrounding 3D anatomical structures by combining MRTD and vascular contrast-enhanced thoracic computed tomography (CT) images in dogs.
Five adult male beagle dogs (11.4-12.8 kg) were included in this study. Sagittal and transverse T2-weighted images were scanned in MRI. Scanning in MRTD used a single-shot fast spin echo sequence with a respiratory gate. CT was performed after the intravenous injection of contrast medium. All MRTD and CT images were merged using a workstation.
The thoracic ducts were identified in MRTD images of all dogs, and the surrounding anatomical structures were located with the aid of contrast-enhanced thoracic CT. In all dogs, the thoracic ducts coursed along the right-dorsal side of the aorta, cranially from the L2 level. Thereafter, these bent to the left side at the aortic arch and curved at the left external jugular vein angle. A comparison of the number of thoracic ducts at each vertebra between transverse T2WI and MRTD did not reveal any significant differences for all vertebrae.
The results from our study suggest that MRTD using the single-shot fast spin echo sequence could be a useful tool for visualization of the thoracic duct. Furthermore, the image merged from MRTD and vascular-enhanced images provided detailed anatomical annotation of the thorax. The MRTD protocol described in this study is safe and easily adaptable, without the need for contrast medium injection into the lymph system. In addition, the images fused from MRTD and vascular contrast-enhanced CT image of the thorax could provide detailed anatomical annotations for preoperative planning.
在人体中，已经尝试通过磁共振成像（MRI）来可视化胸导管，最近的进展使临床医生能够以侵入性较小的方式可视化胸导管的形态。此外，MRI 不需要造影剂，并且能够可视化胸导管结构的形态细节。在兽医实践中，尚未在 MRI 中对胸导管进行三维可视化。
本研究旨在评估我们的磁共振胸导管成像（MRTD）技术在犬中结合 MRTD 和血管增强胸部 CT（CT）图像来可视化胸导管和周围 3D 解剖结构的性能。
本研究纳入了 5 只成年雄性比格犬（11.4-12.8kg）。在 MRI 中进行矢状面和横断面 T2 加权成像。MRTD 扫描使用带呼吸门控的单次激发快速自旋回波序列。静脉注射造影剂后进行 CT 扫描。所有 MRTD 和 CT 图像均使用工作站进行融合。
所有犬的 MRTD 图像均能识别胸导管，借助增强胸部 CT 可定位周围解剖结构。在所有犬中，胸导管沿主动脉的右背侧从 L2 水平向头侧走行。此后，在主动脉弓处向左弯曲，并在左颈外静脉角处弯曲。在所有椎骨中，横断 T2WI 与 MRTD 之间的每一个椎骨的胸导管数量没有显著差异。
本研究结果表明，使用单次激发快速自旋回波序列的 MRTD 可能是可视化胸导管的有用工具。此外，从 MRTD 和血管增强图像融合的图像提供了胸部的详细解剖注释。本研究中描述的 MRTD 方案是安全且易于适应的，无需向淋巴系统注射造影剂。此外，从 MRTD 和血管增强 CT 图像融合的图像可以为术前计划提供详细的解剖注释。
