Single-Sided Magnet System for Quantitative MR Relaxometry and Preclinical In-Vivo Monitoring

Objective: We have developed a single-sided magnet system that allows Magnetic Resonance relaxation and diffusion parameters to be measured. Methods: A single-sided magnet system has been developed, using an array of permanent magnets. The magnet positions are optimised to produce a B-0 magnetic field with a spot that is relatively homogenous and can project into a sample. NMR relaxometry experiments are used to measure quantitative parameters such as T-2, T-1 and apparent diffusion coefficient (ADC) on samples on the benchtop. To explore preclinical application, we test whether it can detect changes during acute global cerebral hypoxia in an ovine model. Results: The magnet produces a 0.2 T field projected into the sample. Measurements of benchtop samples show that it can measure T-1, T-2 and ADC, producing trends and values that are in line with literature measurements. In-vivo studies show a decrease in T-2 during cerebral hypoxia that recovers following normoxia. Conclusion: The single-sided MR system has the potential to allow non-invasive measurements of the brain. We also demonstrate that it can operate in a pre-clinical environment, allowing T-2 to be monitored during brain tissue hypoxia. Significance: MRI is a powerful technique for non-invasive diagnosis in the brain, but its application has been limited by the requirements for magnetic field strength and homogeneity that imaging methods have. The technology described in this study provides a portable alternative to acquiring clinically significant MR parameters without the need for traditional imaging equipment.

Automated summary

Objective: A single-sided magnet system is developed for measuring Magnetic Resonance relaxation and diffusion parameters. Methods: This system uses an array of permanent magnets to optimize magnet positions and produce a homogeneous B-0 magnetic field that can project into a sample. Results: The magnet produces a 0.2 T field and can measure T-1, T-2, and ADC parameters. In-vivo studies show its potential for non-invasive measurements in the brain, such as monitoring T-2 during cerebral hypoxia.