SOURCES OF HETEROGENEOUS CONTRAST ENHANCEMENT IN THE GASTROINTESTINAL-TRACT

Water soluble gadolinium chelates demonstrate heterogeneous enhancemen t of the gastrointestinal tract (GI) when administered orally. To inve stigate the causes, ProHance (2.0 mM) was administered orally to rats. There was a dramatic enhancement of rat GI lumen signal intensity in T-1-weighted MR images which provided increased contrast relative to t he adjacent abdominal tissues. Heterogeneity of MRI signal enhancement along the rat GI tract was investigated by sampling rat GI fluid at v arious times post-ingestion and at different locations along the GI tr act. The corresponding T-1 and T-2 relaxation times, Gd concentrations , and viscosities of each GI fluid sample revealed that changes in eac h of these parameters contribute to the observed heterogeneity of MRI signal enhancement.