[Superparamagnetic iron particles. The clinical results in the MR diagnosis of liver metastases].

The diagnostic value of superparamagnetic iron particles as a tissue-specific MR contrast medium of the reticulo-endothelial system was studied in 30 patients. All patients had liver metastases (maximally 5 known metastases on MR). The patients were examined on a 1.5 Tesla scanner before and after a slow intravenous injection of iron particles (AMI-25) at a dose of 15 mumol/kg. Contrast injection led to a significant reduction of signal strength in the liver parenchyma (p < or = 0.001) but not in the metastases. Contrast enhanced spin echo sequences (SE 2300/45) provided the most marked liver/tumour contrast, greater than the contrast values of T1- and T2-weighted images (p < or = 0.01). After the intravenous injection of iron particles, small metastases in particular are more easily demonstrated. A new, rapid T2-weighted pulse sequence (PSIF 10/15/15 degrees) results in the elimination of vascular signals and leads to better differentiation between lesions and intrahepatic vessels. The use of superparamagnetic iron particles as an MR contrast medium improves the demonstration of liver metastases.