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.