Clinical evaluation of multishot echo planar imaging after administration of superparamagnetic iron oxide for hepatic tumors

Ten cases of hepatocellular carcinoma and three cases of metastatic liver tumor were evaluated using breath-hold multishot echo planar imaging (EPI) before and after administration of super-paramagnetic iron oxide (SPIO), and the results were compared to those with breath-hold fast multi-planar SPGR (T1WI) and fat-suppressed respiratory-triggered FSE (T2WI). Qualitative imaging evaluation of lesion detectability showed that T2WI was much more useful than T1WI as previously reported, and more useful than EPI. Quantitative evaluation showed that the signal to noise (S/N) ratios of the liver parenchyma decreased after administration of SPIO and the changes were significant on all pulse sequences. The change ratio of the S/N ratio of the liver parenchyma after administration of SPIO on EPI was significantly higher than on T1WI and T2WI. The tumor-liver contrast to noise (C/N) ratios increased after administration of SPIO and the changes were significant on T1WI and T2WI, but not on EPI. These results suggested that the tumor S/N ratio decreased after administration of SPIO on EPI. The tumor diameters on EPI were significantly reduced after administration of SPIO. Magnetization and flow artifacts on EPI were detected in all cases and caused distortion: the signal decreased in the liver parenchyma. We concluded that EPI after administration of SPIO is not currently useful compared to other pulse sequences and cannot yet replace T2WI. (author)