Solid-state nuclear magnetic resonance microscopy demonstrating human dental anatomy

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. Study design. Using a Bruker spectrometer AMX 300 WB (300 MHz, 7.1 T) with a microirnaging 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 mum. Conclusion. 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.