ABSTRACT
Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy are important technologies for studying small animals in vivo. Practically all magnetic resonance (MR) studies are performed using pulse excitation and Fourier transform-based detection of the nuclear magnetic resonance signal. Multidimensional MR spectroscopy takes advantage of an additional encoding of nuclei signals with different chemical shifts using various mechanisms. MRI can be considered as an extension of multidimensional MR spectroscopy and utilizes gradients of the static B0 magnetic field to achieve spatial encoding of MR signals. Adding spectroscopy or the frequency chemical shift domain to traditional MRI has enabled the visualization of important chemical information such as absolute concentrations of metabolites in brain that can be digitally superimposed with morphological images. MRI contrast agents are extensively used to modify the intrinsic contrast of MR images by enhancing relaxation of a specific pool of water molecules that provide contribution to the measured MRI signals.
