Project Details
Projekt
Comprehensive refinement of advanced magnetic resonance image acquisition and post-processing techniques to quantify glycosaminoglycan content as a biomarker of lumbar intervertebral disc composition.
Subject Area
Radiology
Term
since 2024
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 530863408
Back pain is a very common condition and affects more than 600 million patients worldwide. The prevalence in Germany was greater than 60% in the last 12 months. Per patient 1300 € are incurred annually, so that the socioeconomic relevance is to be considered high. Back pain is often accompanied by degenerative changes in the intervertebral discs. Degeneration is in turn related to changes in the concentration of various proteoglycans (PG), such as aggrecan and hyaluronic acid. This causes the pressure resistance and changes of the biomechanical properties of the intervertebral disc. In addition, the height of the disc decreasing. Quantitative imaging using MRI makes it possible to visualize changes in the composition of the intervertebral discs, which are related to the proteoglycan content. CEST is a method that allows the chemical exchange of glycosaminoglycans (GAG) to be visualized and thus the GAG content to be quantified. The GAG content in turn correlates with the PG concentration. CEST imaging of GAG – also known as gagCEST- uses radiofrequency pulses at specific resonance frequencies of the hydroxyl protons of the GAGs for this purpose. This reduces the magnetization of these hydroxyl protons. Through the process of chemical exchange, this reduction is transferred to the water reservoir, resulting in a measureable signal change in the MR images. Compared to spectroscopy, gagCEST imaging benefits from higher sensitivity. Sodium imaging uses a different principle to determine PG content: PGs are accompanied by a negative fixed charge density, which attracts positive sodium ions. Therefore, by acquiring the sodium signal, an inference can be made about the PG concentration. Special amplifiers and coils are required for sodium imaging. Due to the lower gyromagnetic ratio compared to water, as well as the lower abundance, a lower MR signal is expected when imaging sodium compared to standard MRI. The goal of this proposal is to systematically and comprehensively optimize both gagCEST and sodium imaging to enable quantitative assessment of intervertebral discs. After validation in a research context using simulations and ex-vivo intervertebral discs, the technique will be transferred to a clinical setting, allowing improved diagnosis and therapy monitoring in patients with early signs of degeneration, which is currently not possible with standard proton-based MR sequences.
DFG Programme
Research Grants
Co-Investigators
Professor Armin Nagel, Ph.D.; Professor Dr. Moritz Zaiss
