1H magnetic resonance spectroscopy in human hydrocephalus

Abstract

Purpose To evaluate cerebral metabolism in clinical hydrocephalus with ¹H magnetic resonance spectroscopy (MRS). Materials and Methods In 24 children and adults with progressive, arrested, or normal pressure hydrocephalus, long-echo time ¹H MR spectra were acquired from periventricular white matter and intraventricular cerebrospinal fluid (CSF). Metabolite ratios, and the presence of lactate, were compared with 38 age-matched controls. Results Metabolite ratios of patients were within the 95% confidence interval (CI) of controls. A small lactate resonance was detected in 20% of control and hydrocephalic subjects. Lactate was consistently visible in CSF spectra, though lactate concentrations were normal. The CSF lactate T₂ was long in comparison with the known intracellular metabolite T₂ relaxation times. In three neonates with hydrocephalus and spina bifida, 3-hydroxybutyrate was detected in CSF in vivo. Conclusion Within the limits of the present methods, ¹H MRS could not detect cerebral metabolic abnormalities in human hydrocephalus and provided no additional diagnostic information. The long T₂ of lactate in CSF explains its high visibility. Hence, the detection of lactate in spectra acquired from voxels that contain CSF does not necessarily imply cerebral ischemia. J. Magn. Reson. Imaging 2003;17:291–299.