title: Measurement of intervertebral disc pressure with T 1ρ MRI.
abstract: The aim of this study is to demonstrate T(1ρ) MRI's capability for measuring intervertebral disc osmotic pressure. Self-coregistered sodium and T(1ρ) -weighted MR images were acquired on ex vivo bovine intervertebral discs (N = 12) on a 3 T clinical MRI scanner. The sodium MR images were used to calculate effective nucleus pulposus fixed-charge-density (mean = 138.2 ± 27.6 mM) and subsequently osmotic pressure (mean = 0.53 ± 0.18 atm), whereas the T(1ρ) -weighted images were used to compute T(1ρ) relaxation maps. A significant linear correlation (R = 0.56, P < 0.01) between nucleus pulposus fixed-charge-density and T(1ρ) relaxation time constant was observed. More importantly, a significant power correlation (R = 0.72, P < 0.01) between nucleus pulposus osmotic pressure as predicted by sodium MRI and T(1ρ) relaxation time constant was also observed. The current clinical method for assessing disc pressure is discography, which is an invasive procedure that has been shown to have negative effects on disc biomechanical and biochemical properties. In contrast, T(1ρ) MRI is noninvasive and can be easily implemented in a clinical setting due to its superior signal-to-noise ratio compared with sodium MRI. Therefore, T(1ρ) MRI may serve as a noninvasive clinical tool for the longitudinal evaluation of disc osmotic pressure.
authors.affiliation: Department of Bioengineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6100, USA. wangch@seas.upenn.edu
authors.forename: Chenyang
authors.initials: C
authors.lastname: Wang
authors.forename: Walter
authors.initials: W
authors.lastname: Witschey
authors.forename: Mark A
authors.initials: MA
authors.lastname: Elliott
authors.forename: Arijitt
authors.initials: A
authors.lastname: Borthakur
authors.forename: Ravinder
authors.initials: R
authors.lastname: Reddy
mesh_terms: D000818:Animals; D002417:Cattle; D007091:Image Processing, Computer-Assisted; D007403:Intervertebral Disc / Q000033:anatomy & histology*; D016014:Linear Models; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D011312:Pressure