The objective is to evaluate whether an ex-vivo model can be used to t
est intracellular contrast agents for MR imaging of the liver. T1 weig
hted inversion recovery, proton density spin echo and T2 weighted gra
dient echo images of the liver were acquired at 0.5 T in 10 rats befor
e and 30 min after intravenous injection of 0.075 mmol/kg Gadolinium b
enzyloxypropionictetraacetate (Gd-BOPTA, n = 5) or 0.015 mmol/kg dextr
an magnetite (DM, n = 5), Four additional animals served as controls.
After exsanguination and perfusion with saline and formalin, specimens
of the liver and brain were embedded in an agar gel and examined with
MR imaging one to three weeks later using the same protocol. Zn-vivo,
the mean liver signal enhancement caused by Gd-BOPTA in T1, proton de
nsity and T2 weighted images was +23%, +28% and -70%, respectively. T
he mean liver signal enhancement caused by DM was -71%, -76% and -94%.
In-vitro, no signal change was seen in the brain of animals injected
with Gd-BOPTA and DM as compared to controls. Liver signal was increas
ed by Gd-BOPTA and decreased by DM. Mean liver enhancement rate induce
d by Gd-BOPTA was +22%, +5% and +27% for T1, proton density and T2 we
ighted images, respectively. Mean liver enhancement rate induced by DM
was -27%, -19% and -31%. MR imaging signal changes induced by liver i
ntracellular contrast agents are still appreciable in an ex-vivo model
. The latter might be useful for for preliminary investigation of intr
acellular contrast agents for MR imaging of the liver. (C) 1997 Elsevi
er Science, Inc.