SOFT TISSUE MATRIX CHARACTERIZATION USING STRETCHED EXPONENTIAL RELAXATION MODELING

摘要

A process for more sensitive characterization of tissue composition for generating a quantitative MRI (qMRI) map and corresponding delta analysis. Intervertebral disc degeneration (IVDD), resulting in the depletion of hydrophilic glycosaminoglycans (GAGs) located in the nucleus pulposus (NP), can lead to debilitating neck and back pain. Magnetic Resonance Imaging (MRI) is a promising means of IVD assessment due to the correlation between GAG content and MRI relaxation values. T1 and T2 relaxation data were obtained from healthy cervical IVDs, and relaxation data was modeled using both conventional and stretched exponential (SE) decays. Normalized histograms of the resultant quantitative MRI (qMRI) maps were fit with stable distributions. SE models fit relaxation behavior with lower error compared to monoexponential models, indicating anomalous relaxation behavior in healthy IVDs. SE model parameters T1 and T1 increased with IVD segment, while conventional monoexponential measures did not vary. The improved model fit and correlation between both SE T1 and T1 with IVD level suggests these parameters are more sensitive biomarkers for detection of GAG content variation.