title: Solid-state nuclear magnetic resonance microscopy demonstrating human dental anatomy.
abstract: OBJECTIVE
  Magnetic resonance imaging has become a common diagnostic tool in medical practice. It is a common view that solid-state material lacking a sufficient amount of unpaired nuclear spins, in particular proton spins, is impossible to depict with clinically used magnetic resonance devices. Characteristically rapid dephasing, caused by relatively short spin-spin relaxation (T(2) time) also leads to broad resonance lines. A newly introduced technique, constant-time imaging, uses 3 phase-encoding gradients for the acquisition of only one complex data point per phase-encoding step, resulting in detection times of only a few microseconds and extremely sharp resonance lines.
  
  
  METHODS
  Using a Bruker spectrometer AMX 300 WB (300 MHz, 7.1 T) with a microimaging attachment, we performed solid-state magnetic resonance imaging of whole teeth. Data processing was carried out by means of 3-dimensional Fourier analysis, and reconstructions were performed by the ParaVision (Bruker) software system.
  
  
  RESULTS
  Dental hard tissues (enamel, dentin, and root cementum) and pulpal soft tissue could be depicted in 2-dimensional and 3-dimensional images. The voxel resolution isotropically reached 195 microm.
  
  
  CONCLUSIONS
  The constant-time imaging technique enabled a naturalistic and nondestructive visualization of the teeth without application of ionizing radiation. This technique bears the potential to help us overcome the limitations of clinically used standard magnetic resonance tomography devices and offers new perspectives for dental imaging.
authors.affiliation: Department of Oral and Maxillofacial Surgery, University of Bonn, Germany. appel@uni-bonn.de
authors.forename: Thorsten R
authors.initials: TR
authors.lastname: Appel
authors.forename: Michael A
authors.initials: MA
authors.lastname: Baumann
mesh_terms: D019412:Anatomy, Cross-Sectional; D003739:Dental Cementum / Q000033:anatomy & histology; D003743:Dental Enamel / Q000033:anatomy & histology; D003782:Dental Pulp / Q000033:anatomy & histology; D003786:Dental Pulp Cavity / Q000033:anatomy & histology; D003804:Dentin / Q000033:anatomy & histology; D004578:Electron Spin Resonance Spectroscopy; D005583:Fourier Analysis; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009682:Magnetic Resonance Spectroscopy; D008853:Microscopy / Q000379:methods; D012984:Software; D013057:Spectrum Analysis; D013997:Time Factors; D014070:Tooth / Q000033:anatomy & histology*; D014092:Tooth Root / Q000033:anatomy & histology