Proton MRS in neurological disorders.

Proton magnetic resonance spectroscopy (1H MRS) permits the acquisition of the signal arising from several brain metabolites. At long echo-time (TE) 1H MRS can detect N-acetyl-aspartate containing compounds, choline containing compounds, creatine + phosphocreatine and lactate. At short TE, lipids, tryglicerides, alanine, glutamate, glutamine, GABA, scyllo-inositol, glucose, myo-inositol, carnosine and histydine are visible. 1H MRS can be performed with single-voxel, multivoxel, single slice and multislice techniques. With single voxel 1H MRS it is possible to measure metabolites relaxation time, which allows the measurement of metabolite concentrations. This technique can be useful in the study of focal lesions in the central nervous system (CNS) such as epilepsy (pre-surgical identification of epileptic focus), brain tumors (evaluation of recurrence and radiation necrosis), stroke, multiple sclerosis, etc. Single slice and multislice 1H MRS imaging (1H MRSI) can be performed only at long TE and permits the mapping of the brain metabolites distribution which makes them particularly useful in studying diffuse diseases and heterogeneous lesions of the CNS. 1H MRS can also be useful in the evaluation of 'ischemic penumbra' of stroke; developmental (myelin and neuronal dysgenesis); head trauma (evaluation of cerebral damage not visible with MRI); degenerative disorders (identification of microscopic pathology not visible with MRI); and metabolic diseases (metabolic disturbances with specific metabolic patterns).