Department of Radiology - Medical Physics, University Medical Center, Freiburg, Germany.
J Magn Reson Imaging. 2012 Oct;36(4):841-6. doi: 10.1002/jmri.23712. Epub 2012 Jun 15.
To evaluate the ability of conventional and ultra-short or zero echo time MRI for imaging of soft and solid dental components in and ex vivo.
Turbo spin echo (TSE), ultra-short echo time (UTE), and zero echo time (ZTE) MRI were performed on extracted (human and equine) teeth and in vivo using whole-body and small-bore MR systems at 3 T, 7T, and 9.4T, respectively.
At an isotropic resolution of (600 μm)(3) , strong signal of soft-tissue, e.g., mucosa and nerves with excellent contrast was achieved using TSE at 3T in vivo. No signal, though, was obtained from solid components, e.g., teeth (due to short T(2) ). In contrast, dentin, cementum as well as enamel of extracted teeth were readily depicted using UTE and ZTE at a resolution of ≈ (150 μm)(3) at 7T and 9.4T. In particular, ZTE provided higher signal in enamel.
As an alternative to X-ray based methods like cone-beam computed tomography (CT) or conventional CT, the presented results demonstrate the potential of ZTE and UTE MRI as a radiation-free imaging modality, delivering contrast of soft and solid components at the same time.
评估常规和超短或零回波时间 MRI 成像口腔软硬组织的能力，包括在体和离体研究。
分别使用 3T、7T 和 9.4T 的全身和小口径 MR 系统，对离体（人牙和马牙）和在体牙齿进行了涡轮自旋回波（TSE）、超短回波时间（UTE）和零回波时间（ZTE）MRI 扫描。
在各向同性分辨率为（600μm）³时，在 3T 时，TSE 在活体中可获得软组织（如黏膜和神经）的强信号，且对比度良好。然而，由于 T2 较短，无法从固体组织（如牙齿）中获得信号。相比之下，在 7T 和 9.4T 时，分辨率约为（150μm）³的 UTE 和 ZTE 可轻易显示离体牙齿的牙本质、牙骨质和牙釉质。特别是，ZTE 可在牙釉质中提供更高的信号。
作为基于 X 射线的方法（如锥形束 CT（CBCT）或常规 CT）的替代方法，本研究结果表明 ZTE 和 UTE MRI 具有作为一种无辐射成像方式的潜力，可同时提供软组织和硬组织的对比度。
