Oral magnetic particles as a contrast agent for MR imaging of the abdomen. A phase III clinical trial.

Twenty patients were investigated with MR imaging of the abdomen before and after the administration of oral magnetic particles in the form of a per os solution for opacification of the gastrointestinal lumen. The parameters which were evaluated were a) distribution of the contrast medium in the gastrointestinal tract, b) delineation with the contrast medium of the region of interest c) image quality of general contract effect of the contrast medium d) diagnostic accuracy compared with CT and plain MRI of the same region. At a concentration of 0.5 mg/oral magnetic particles produced a constant negative signal from the gastro- intestinal tract in all spin echo sequences (T1 weighted, T2 weighted, proton density). Its diagnostic accuracy was similar to CT but better than plain MR examination of the same region in 70% of the cases. The diagnostic accuracy was inferior in the lower abdomen because of underdistension of the bowel. Perhaps the solution to the problem would be the combined per os and per rectum administration of the contrast medium.