Evaluation of the time window for Resovist-enhanced T2-weighted MRI of the liver.

Superparamagnetic iron oxides (SPIO) are phagocytized in the reticuloendothelial system (RES) of the liver and spleen. Most liver tumors are devoid of RES cells and do not show uptake of SPIO. Therefore, SPIO increase tumor-liver contrast and subsequently the detection and the characterization of liver tumors (1 6). Contrastenhanced MRI may be performed as early as 10 min following administration of the new SPIO SHU 555 A with a blood half-live 3.9 5.8 min (7, 8). With the upcoming clinical approval of this new SPIO the question arises how long the time window for a stable contrast-enhanced T2-weighted MRI of the liver will be. Thus, the purpose of this study was to estimate the time window for contrast-enhanced MRI of the liver with SHU 555 A by measuring signal intensity within the liver and liver tumors on T2-weighted MRI over a period up to 2 weeks following contrast administration.