title: A model of unloaded human intervertebral disk based on NMR relaxation.
abstract: NMR relaxation rates were related to the composition of the nucleus pulposus from 11 and anulus fibrosus from six human intervertebral disks. Tissue water was proportional to glycosaminoglycan (GAG) and residue, the noncollagen, non-GAG portion of the dry weight (R2 = 0.74). The solid signal fraction depended on collagen and residue protons (R2 = 0.89). 1/T1 was proportional to collagen and residue (R2 = 0.97). T2 showed 2-4 components labeled A, B, C, and D, with means +/- standard deviations of 3.1 +/- 1.6, 17.5 +/- 9.5, 64 +/- 22, and 347 +/- 162 msec. Signal fractions of A and B depended on the collagen-associated water protons (R2 = 0.94 and 0.85), C on residue-associated water protons (R2 = 0.82), and D on GAG-associated water protons (R2 = 0.74). The data led to a model of disk architecture in which the collagen and residue were largely solid, forming distinct water compartments; the remaining water was present in a proteoglycan gel.
authors.affiliation: Department of Physics, Faculty of Science, University of British Columbia, Vancouver, Canada.
authors.forename: T
authors.initials: T
authors.lastname: Nightingale
authors.forename: A
authors.initials: A
authors.lastname: MacKay
authors.forename: R H
authors.initials: RH
authors.lastname: Pearce
authors.forename: K P
authors.initials: KP
authors.lastname: Whittall
authors.forename: B
authors.initials: B
authors.lastname: Flak
mesh_terms: D001834:Body Water / Q000737:chemistry; D002102:Cadaver; D003094:Collagen / Q000737:chemistry*; D006025:Glycosaminoglycans / Q000737:chemistry*; D006801:Humans; D007403:Intervertebral Disc / Q000737:chemistry*; D008159:Lumbar Vertebrae; D009682:Magnetic Resonance Spectroscopy; D008954:Models, Biological; D011336:Probability; D012680:Sensitivity and Specificity
chemical_list: D006025:Glycosaminoglycans; D003094:Collagen