A-224 C. Metabolic disorders
J.F. Schneider | Saturday, March 9, 08:30 – 10:00 / Room E2
Metabolic disorders may present at any age. Their clinical symptoms are often scarce or non-specific. Brain MRI is often used in the setting of an acute illness but may be delayed in slowly progressive disease. Imaging appearance can be confusing as acute and chronic signal intensity alterations may overlap in many disorders. Furthermore, imaging appearance will vary during the course of the disease. Recognition of signal changes in specific structures is most helpful in the acute setting before chronic changes set in, which will blur characteristic patterns. A systematic approach based on the pattern of brain involvement is useful in the analysis of neurometabolic disorders, and has even been computerized. First, a decision whether grey or white matter involvement or both must be made based upon volume and signal alterations on T1-wi, T2-wi, FLAIR imaging and contrast enhancement. Second, alterations within either focal grey matter structures or specific white matter tracts must be recorded and estimation upon their timing, whether acute or chronic, must be made. Finally, this pattern recognition must be supplemented by microstructural data from diffusion-weighted images (DWI) and metabolic data from proton MR spectroscopy (MRS). Additional information from DWI is often restricted to the acute setting, because chronic diffusivity changes are mainly driven by unspecific myelin breakdown. On the other hand, MRS may not only identify abnormal levels of normal metabolites or demonstrate the presence of abnormal metabolites, but can also be used to monitor therapy.