WHAT IS BRIGHT ON T1-WEIGHTED MR SCANS

The list of entities associated with a high signal intensity on T1-wei ghted images is extensive and classically includes fat, proteins, hemo rrhage, melanin and gadolinium. However, additional entities may be re sponsible for abnormally high signal intensity on T1-weighted images. These include ion deposition in metabolic disorders, free radicals, in creased proton density, flow phenomena, some artifacts, and new contra st agents. The aim of this article is to display both the common and u ncommon causes for a high T1 signal intensity and to discuss the under lying mechanisms or attributable pathophysiology for this phenomenon.