SUPERPARAMAGNETIC IRON PARTICLES - 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 mu mol/kg. Contrast injection led to a significant reduction of signal strength in the liver parenchyma (p less than or equal to 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 T-1- and T-2-weighted images (p less than or equal to 0.01). After the intravenous injection of iron particles, small metastases in particular are more easily demonstrated. A new, rapid T-2-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.