Syllabus

This talk will walk you through the basics and applications of three quantitative MR methods for a non-invasive articular cartilage structure analysis: diffusion MRI, gagCEST and sodium MRI. The extracellular matrix (ECM) of articular cartilage constrains free diffusion of water molecules. DWI allows for estimation of the integrity of ECM based on the motion of water molecules. The main challenges are short T2 of cartilage, macroscopic motion and complex joint anatomy. Different acquisition strategies (EPI, SE, SSFP, GRE) will be discussed as well. An in vivo 23Na MRI is a non-invasive tool that provides valuable information on cell metabolism; however, this technique is extremely challenging due to number of technical and physiological pitfalls. In this lecture, the aim is to provide a review of recent 23Na-MRI development and application in articular cartilage. gagCEST belongs to Chemical Exchange Saturation Transfer (CEST) family, it is a magnetic resonance imaging (MRI) contrast enhancement technique that enables indirect detection of metabolites with exchangeable protons (-OH and -NH chains in glycosaminoglycans). CEST effect depends on several factors such as field strength (B0), concentration of metabolite with exchanging spins, exchange rate, B0 and B1 field homogeneities, T1 of water protons, RF saturation pulse duration and amplitude. The recent developments and applications of gagCEST will be discussed.

Acknowledgements

This work was supported by the Austrian Science Fund (FWF) project KLI 541-B30 and KLI 917. The financial support by the Austrian Federal Ministry for Digital and Economic Affairs and the National Foundation for Research, Technology and Development is gratefully acknowledged.