Sources of heterogeneous contrast enhancement in the gastrointestinal tract

Water soluble gadolinium chelates demonstrate heterogeneous enhancement of the gastrointestinal tract (GI) when administered orally. To investigate the causes, ProHance (2.0 mM) was administered orally to rats. There was a dramatic enhancement of rat GI lumen signal intensity in T1-weighted MR images which provided increased contrast relative to the adjacent abdominal tissues. Heterogeneity of MRI signal enhancement along the rat GI tract was investigated by sampling rat GI fluid at various times post-ingestion and at different locations along the GI tract. The corresponding T1 and T2 relaxation times, Gd concentrations, and viscosities of each GI fluid sample revealed that changes in each of these parameters contribute to the observed heterogeneity of MRI signal enhancement.