Metabolic MRI: Fiction and Reality
Trinity College Dublin, Ireland
Abstract
Magnetic resonance imaging (MRI) is a non-invasive technique which enables to spatially resolve signals originating from hydrogen-1 nuclei. However, also other MRI-active nuclei, e.g. sodium-23, phosphorus-31, carbon-13, potassium-39, and chlorine-35 can be observed using MRI scanners capable of broadband radio-frequency (rf) excitation. The mammal metabolism involves many of these so called X-nuclei. Hence, MRI of these nuclei may provide a useful method to study the human metabolism in normal and pathological conditions non-invasively. So far, metabolic MRI has been challenging due to the lack of sufficient signal sensitivity resulting in poor spatial resolution by comparison to standard hydrogen-1 MRI. In this talk, pragmatic approaches to improve the signal-to-noise-ratio per voxel size and acquisition time are presented. For instance, optimized rf detectors can help to drastically improve the signal sensitivity and hence allow for the observation of metabolic processes such as the swelling of cells in brain tissue after arterial occlusion. The ability to thus acquire whole-body sodium-23 MR images of the human demonstrates that metabolic 3D scanning methods are clinically practical. Hence, the diagnostic question of whether tissue is partially dead or still alive at a given point in time may be answered non-invasively in the future, e.g. to inform treatment for stroke or tumor therapy patients.