Dental MRI: Imaging of soft and solid components without ionizing radiation

Purpose: 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. Materials and Methods: 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. Results: At an isotropic resolution of (600 mu m)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 T2). In contrast, dentin, cementum as well as enamel of extracted teeth were readily depicted using UTE and ZTE at a resolution of (150 mu m)3 at 7T and 9.4T. In particular, ZTE provided higher signal in enamel. Conclusion: 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. J. Magn. Reson. Imaging 2012;36:841846. (c) 2012 Wiley Periodicals, Inc.