NON-INVASIVE MEASUREMENT OF INTERVERTEBRAL DISC OSMOTIC PRESSURE WITH T1P MRI

这个子项目是众多研究子项目之一

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Intervertebral disc degeneration is a common and sometimes debilitating condition affecting a significant percentage of the population. The earliest stage of disc degeneration involves the breakdown and subsequent depletion of proteoglycans in the nucleus pulposus region of the disc, which results in decreased hydrostatic pressure in discs. Sodium MRI has previously been used to calculate the fixed-charge-density of the nucleus tissue, which can subsequently be used to calculate the osmotic pressure generated by the sodium cations attracted by the fixed-charge on proteoglycans. The osmotic pressure of intervertebral disc is linearly related to the hydrostatic pressure, which is an importantly biomechanical property of the intervertebral disc. The current clinical technique for the assessment of intervertebral disc pressure is discography, which is an invasive procedure that has been shown to initiate and exacerbate intervertebral disc degeneration. In this study, we intend to first optimize a protocol to use sodium MRI to measure osmotic pressure in intact intervertebral disc samples. However, due to its low signal-to-noise ratio efficiency, sodium MRI's clinical applicability is limited. In contrast, T1¿ MRI has been shown to be an accurate technique for measuring fixed-charge-density in fibrocartilage such as articular cartilage and intervertebral disc. In addition, since T1¿ targets proton nuclei like conventional MRI techniques, it has comparatively higher signal-to-noise ratio efficiency compared to sodium MRI, which makes it more readily to be applied in clinical setting. Therefore the purpose of this study is to correlate osmotic pressure measured using sodium MRI to T1¿ relaxation time constant of intervertebral discs. In doing so, we can demonstrate T1¿ MRI's clinical utility in the non-invasive measurement of intervertebral disc osmotic pressure.