Single Voxel Proton MR Spectroscopy Methods and Applications in Neuropediatrics

The purpose of this contribution is to introduce quantitative single voxel proton MR spectroscopy of the human brain as an easy-to-use method for a noninvasive assessment of cellular composition and metabolism and to demonstrate its clinical potential in the field of neuropediatrics. The chosen approach transforms fully relaxed (TR = 6000 ms) short echo time (TE = 20 ms) proton MR spectra (STEAM localization sequence) into absolute metabolite concentrations by automatically fitting the raw data with a library of model spectra comprising all metabolites at known concentration (LCModel). The procedure includes total N-acetylaspartyl compounds as a marker for viable neuroaxonal tissue and myo-inositol as a purely glial constituent as well as total creatine, choline-containing compounds, glutamate and glutamine, and lactate. Extensive studies of brain disorders in childhood suggest the use of proton MRS as a promising tool for an in vivo histopathologic characterization of brain tissue. Typical metabolite patterns are observed for pathologic processes such as lactic acidosis, loss of functioning neurons, astrocytosis, myelin breakdown, or loss of oligodendrocytes. Examples deal with the diagnostic workup of enzyme deficiencies, demyelinating white matter diseases, and focal brain lesions.