Assessment of human disc degeneration and proteoglycan content using T1rho-weighted magnetic resonance imaging.
METHODS
T1rho relaxation was quantified and correlated with intervertebral disc degeneration and proteoglycan content in cadaveric human lumbar spine tissue.


OBJECTIVE
To show the use of T1rho-weighted magnetic resonance imaging (MRI) for the assessment of degeneration and proteoglycan content in the human intervertebral disc.


BACKGROUND
Loss of proteoglycan in the nucleus pulposus occurs during early degeneration. Conventional MRI techniques cannot detect these early changes in the extracellular matrix content of the disc. T1rho MRI is sensitive to changes in proteoglycan content of articular cartilage and may, therefore, be sensitive to proteoglycan content in the intervertebral disc.


METHODS
Intact human cadaveric lumbar spines were imaged on a clinical MR scanner. Average T1rho in the nucleus pulposus was calculated from quantitative T1rho maps. After MRI, the spines were dissected, and proteoglycan content of the nucleus pulposus was measured. Finally, the stage of degeneration was graded using conventional T2 images.


RESULTS
T1rho decreased linearly with increasing degeneration (r = -0.76, P < 0.01) and age (r = -0.76, P < 0.01). Biochemical analysis revealed a strong linear correlation between T1rho and sulfated-glycosaminoglycan content. T1rho was moderately correlated with water content.


CONCLUSIONS
Results from this study suggest that T1rho may provide a tool for the diagnosis of early degenerative changes in the disc. T1rho-weighted MRI is a noninvasive technique that may provide higher dynamic range than T2 and does not require a high static field or exogenous contrast agents.
Johannessen
Wade
W
Department of Orthopaedic Surgery, McKay Orthopaedic Research Laboratory, University of Pennsylvania, Philadelphia, PA 19104-6081, USA.
Auerbach
Joshua D
JD
Wheaton
Andrew J
AJ
Kurji
Alykhan
A
Borthakur
Arijitt
A
Reddy
Ravinder
R
Elliott
Dawn M
DM