[Metabolic and functional magnetic resonance imaging of the brain: clinical application to pediatric brain diseases]

We have developed 1H-chemical shift imaging (CSI) and functional magnetic resonance imaging (FMRI) methods on a clinical MRI system, in which metabolic and functional information can be obtained from the brain. 31P- and 1H-CSI are in clinical use. Using 1H-CSI, the peaks of N-acetylaspartate (NAA), choline (Cho) and creatine (Cr) are clearly detected in multiple small voxels. In normal children, the ratio of NAA/Cho increased after birth in different manners in different parts of the brain. The peak of NAA decreased in some disorders with brain damage or neuronal immaturity. It has been shown recently that functional activation of the cortex can be visualized with MR imaging with a blood oxygen level dependent (BOLD) effect. At an activated area, the ratio of deoxyhemoglobin to oxyhemoglobin decreased in the capillary and venous beds. Therefore, with a decrease of the effect of the T2 susceptibility from deoxyhemoglobin, the signal intensity of the activated area increased. CSI and FMRI have a unique possibility in the field of non-invasive brain analysis.