Magnetic starch microspheres in the MR imaging of hepatic metastases

Abstract

Purpose: to evaluate reticular endothelial system-specific magnetic starch microspheres (MSM) as an i.v. contrast agent for MR imaging in a model of experimental liver metastases

Material and Methods: the study comprised 15 nude rats, 7 of which were carrying hepatic metastases from a human colonic cancer. the 15 rats were examined at 0.5 T using a T1-weighted spin-echo (SE) sequence and a gradientecho sequence. the examinations were performed before and 15 min after the administration of accumulated doses of MSM at 0.25–2.5 mg Fe/kg b.w. the images were compared with corresponding serial liver specimens

Results: A loss of liver signal intensity was obtained at all MSM dose levels. No metastases were detected in the pre-contrast images. the optimum detection rate of hepatic metastases was reached with the SE sequence at a dose of 1.0 mg Fe/kg b.w. MSM and the diameters of the smallest lesions depicted were 1 mm. However, in the SE sequence, the measured lesion-to-liver contrast and liver signal damping were highest at the largest dose, indicating a possible image degrading effect of MSM at high doses. Administration of MSM as a short bolus over 30 s resulted in congestion of the liver with dilatation of the hepatic veins. When MSM was instead injected slowly over 5 min, this adverse effect was not seen

Conclusion: the use of MSM dramatically increased the detection of experimental hepatic metastases