PURE PHASE-ENCODED MRI AND CLASSIFICATION OF SOLIDS

In this work, we combine a pure phase-encoded Magnetic Resonance Imaging (MRI) method with a new tissue-classification technique to make geometric models of a human tooth, We demonstrate the feasibility of three-dimensional imaging of solids using a conventional 11.7-T NMR spectrometer. In solid-state imaging, confounding line-broadening effects are typically eliminated using coherent averaging methods. Instead, we circumvent them by detecting the proton signal at a fixed phase-encode time following the radio-frequency excitation. By a judicious choice of the phase-encode time in the MR imaging protocol, we differentiate enamel and dentine sufficiently to successfully apply a new classification algorithm. This: tissue-classification algorithm identifies the distribution of different material types, such as enamel and dentine, in volumetric data. In this algorithm, we treat a voxel as a volume, not as a single point, and assume that each voxel may contain more than one material. We use the distribution of MR image intensities within each voxel-sized volume to estimate the relative proportion of each material using a probabilistic approach. This combined approach, involving MRT and data classification, is directly applicable to bone imaging and hard tissue contrast-based modeling of biological solids.