[Oral contrast media for magnetic resonance tomography of the abdomen. 1. Comparative animal studies of positive and negative contrast media]

Large scale clinical evaluation of bowel contrast agent containing ferric ammonium citrate in MRI

Clear identification of bowel has been thought to be essential in diagnosis by abdominal MRI. We have completed the clinical phase III trial of a new oral contrast agent (FerriSeltz) which is a ferric ammonium citrate based bowel contrast agent. FerriSeltz is a powder that is dissolved in 300 ml water to create a grape-flavored effervescent drink. We have evaluated the usefulness of FerriSeltz, and compared groups receiving 600 mg and 1200 mg of ferric ammonium citrate, the use and nonuse of parasympathetic blockers, and patients with and without fasting in 174 patients who underwent abdominal MRI using this agent. FerriSeltz was found to brighten the stomach and duodenum, contribute to the improvement in diagnostic efficacy, be safe as a bowel contrast agent in abdominal MRI, and be associated with an extremely low incidence of side effects (only mild diarrhea in one of 169 patients). No significant differences were found in the contribution to the improvement in diagnostic efficacy between the two dosage groups, the use and nonuse of parasympathetic blockers, or patients with and without fasting. We concluded that ferric ammonium citrate based compound (FerriSeltz) is a promising bowel contrast agent in abdominal MRI.

A comparative study between Gd-DTPA and oral magnetic particles (OMP) as gastrointestinal (GI) contrast agents for MRI of the abdomen

In the present study we compared two gastrointestinal contrast agents--Gd-DTPA, a positive signal, and oral magnetic particles (OMP), a negative signal contrast agent--in patients who were referred for MR imaging of the abdomen. Altogether 60 patients were examined with the former and 28 patients with the latter contrast before and after the administration of contrast media. Gd-DTPA was given either per os or per rectum. In comparing the results, it was shown that the diagnostic accuracy of postcontrast MRI in both groups was more or less similar to CT but much higher as compared with plain MRI. In the OMP series, first the contrast between the GI-filled lumen and the surrounding fat was much superior to that of the Gd-DTPA and, second, there was no evidence of any artifacts from bowel motion. However, the overall accuracy of the Gd-DTPA group was better compared with that of the OMP group. This was due to underfilling of the distal bowel because the OMP in those patients was administered only per os. Finally, Gd-DTPA had a more pleasant taste and fewer side effects. It is concluded that both contrast media are suitable for the upper abdomen because the results are comparable, whereas for the lower abdomen Gd-DTPA is superior because it can be used from both routes.

Abdominal MRI using a negative contrast agent

A dose of 0.5 g of a negative oral contrast agent for labelling the bowel, was given to 40 patients in a clinical trial. Oral magnetic particles (OMP) consist of crystals of iron oxide with superparamagnetic properties, and are administered in 800 ml of a viscous suspension in order to obtain a uniform distribution. The aim of the study was to identify any adverse effects up to 1 week following ingestion, as well as the contrast distribution and effect, together with the induction of artifacts. A comparison of diagnostic value of the pre and postcontrast ingestion series was also performed. Vomiting followed ingestion in a single patient already nauseated and was the only adverse effect. Good contrast distribution and effect with no artifacts were present. The diagnostic information was greatly improved after OMP ingestion, and the diagnosis would not have been possible without the use of the contrast agent in 41% of the examinations.

Gd-DTPA as an intestinal contrast agent for MR imaging of the lower abdomen: phase III clinical trial

Thirty-one patients were investigated with magnetic resonance (MR) imaging of the lower abdomen before and after the administration of gadopentetate dimeglumine (Gd-DTPA) solution per os or per rectum or from both routes for the opacification of the intestinal tract. The parameters evaluated were: (a) contrast medium distribution, (b) degree of filling of the bowel lumen, (c) contrast between the bowel lumen and the surrounding normal or pathological structures, and (d) whether the administration of the contrast agent improved the diagnostic ability of MR compared to computed tomography (CT) or plain MR of the same region. Gd-DTPA, at a concentration of 1 mmol/L, produced a positive signal irrespective of its dilution in the bowel and good contrast between the bowel lumen and the adjacent tissues or any possible pathological lesions. From the diagnostic point of view, after the administration of contrast medium, MR is comparable to CT and much superior to plain MR. It is concluded that opacification of the bowel with Gd-DTPA solution will improve the diagnostic yield of MR imaging of the lower abdomen.