Functional and pathophysiological study of disease processes in human and animal systems: role of magnetic resonance imaging and in vivo MR spectroscopy

Abstract

Magnetic resonance imaging (MRI), a non-invasive imaging modality, has revolutionized the field of clinical medicine with its multiplanar imaging capability, high spatial resolution, excellent soft tissue contrast and absence of ionizing radiation. It covers a broad range of applications from fast noninvasive anatomical measurements to the study of tissue physiology and metabolism. MR images arise primarily from the protons of water and fat present in human and/or animal tissues. Several variants of MR methods have been developed for studying specific disease processes. Recently, diffusion and perfusion MRI have found widespread application in the evaluation of epilepsy, stroke and other brain disorders. Functional MRI, yet another advance, is useful for studying several brain functions and has immense potential in unravelling the mystery of the human brain. It has the capability of identifying specific anatomical sites involved in many cognitive processes. Another aspect of MR is the so-called in vivo MR spectroscopy of living systems. In vivo MRS of living systems are an extension of the traditional high-resolution NMR method used for studying structure of molecules but applied to more complex systems. Among the various nuclei that generate MR signal, proton (¹H) and phosphorous (³¹P) are important in the study of the biochemistry of living systems. In vivo MRS can be used to observe different biochemicals (metabolites) from a particular specified region of a living system. Determination of the concentration and relative levels of these metabolites provides information on the normal and abnormal states of tissues and their response to various therapeutic modalities. In short, in vivo MRS can be used as a unique means for probing the biochemistry and physiology of living systems. In this article, a general overview of the basics, development and the applications of various MRI and MRS methodologies used in clinical and experimental research are presented to understand the pathophysiology of various disease processes.