PRINCIPLES OF CONTRAST ENHANCEMENT IN THE EVALUATION OF BRAIN DISEASES - AN OVERVIEW

Intravenous contrast media are widely used in MR imaging of the brain, Clinical utility is high in both neoplastic and non-neoplastic diseas e, The agents approved to date are all gadolinium chelates, with extra cellular distribution and renal excretion, The agents differ in regard to the maximum dose that can be administered and the theoretical safe ty margin, When administered at the same dose, the efficacy of the dif ferent available agents is comparable. Described in the following revi ew article are the diagnostic use of contrast media and the patterns o f enhancement encountered in neoplastic disease, infection, vascular d isorders, and diseases of white matter. Only in congenital brain disea se, when acute abnormalities are not suspected clinically and neoplast ic disease is not a question, is contrast enhancement not indicated. T he gadolinium chelates play a major role in the evaluation of patients by MR with known or suspected brain disease. These agents improve bot h the sensitivity and specificity of the examination, In many cases, l esions cannot be identified before contrast administration. Lesion del ineation, assessment of lesion activity, and differential diagnosis ar e all improved, in general, with the addition of postcontrast scans, T he scope of applications continues to expand as the modality and clini cal experience matures.