In Vivo Measurement of Relaxation Time of Water and N-Acetyl in Intervertebral Disc Using MR Spectroscopy

Jin Zuo¹, Xiaojuan Li¹, John Kurhanewicz¹, Sharmila Majumdar¹

Intervertebral disc degeneration (IVDD) related back pain affects about 80% in the general population during the life-time. Traditional imaging techniques rely on disc morphology while actual disc degeneration begins with internal biochemical and biomechanical changes. Proton magnetic resonance spectroscopy (1H-MRS) is a powerful non-invasive tool that has been used for the assessment of metabolites in tissues. Previously, 1H-MRS on a clinical 3T magnetic resonance (MR) scanner has demonstrated the feasibility of using short-echo water suppressed point-resolved spectroscopy (PRESS) for evaluating biochemical changes in cadaveric bovine and human discs. In these studies the degradation of bovine discs, induced by papain digestion, and the prevalent degeneration in cadaveric discs as assessed with Pfirrmann grading was correlated to spectra measures. In this study, we performed single voxel MRS technique in intervertebral discs from healthy volunteers and T1 and T2 relaxation times of water peak and N-acetyl peak of proteoglycan (PG) in the healthy discs were measured. As dehydration and loss of PG are the two primary consequences of disc degeneration, relaxation times may potentially change with degeneration, and quantification of relaxation times might provide valuable information related to disc degeneration.