title: Pure phase-encoded MRI and classification of solids.
abstract: Here, the authors combine a pure phase-encoded magnetic resonance imaging (MRI) method with a new tissue-classification technique to make geometric models of a human tooth. They 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, the authors 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 MRI protocol, the authors 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, the authors treat a voxel as a volume, not as a single point, and assume that each voxel may contain more than one material. They 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 MRI and data classification, is directly applicable to bone imaging and hard-tissue contrast-based modeling of biological solids.
authors.affiliation: Div. of Biol., California Inst. of Technol., Pasadena, CA.
authors.forename: P
authors.initials: P
authors.lastname: Ghosh
authors.forename: D H
authors.initials: DH
authors.lastname: Laidlaw
authors.forename: K W
authors.initials: KW
authors.lastname: Fleischer
authors.forename: A H
authors.initials: AH
authors.lastname: Barr
authors.forename: R E
authors.initials: RE
authors.lastname: Jacobs