[Basic and clinical studies of oral barium sulfate preparations for CT]

In CT examination of the abdomen and pelvis, oral iodinated contrast agents and oral barium sulfate preparations are now being used to improve diagnostic accuracy, and studies have been carried out on their clinical usefulness. Although helical CT has come into wide spread use recently, most studies have used the ordinary type of CT. There have been no reports on studies using barium sulfate preparations with helical CT. We, therefore, prepared several barium sulfate preparations with different concentrations and particle diameters, and conducted a basic study to determine the optimal conditions for helical CT. In addition, we conducted a similar study using the ordinary imaging method for comparison with helical CT. Based on the results of these studies, we conducted a clinical study with several volunteers to find the most suitable barium sulfate preparation. Our basic study compared Baritop CT and Gastrografin, and a concentration of 1.5%-2.0% was found suitable. In our examination of particle size using animal intestines, fine particles were found to be most appropriate. Although little difference was observed between the helical procedure and the ordinary imaging procedure, the possible development of artifacts specific to the helical procedure was suggested. In the clinical study, the 2.0% preparation tended to show better contrast and a better filling rate for the upper abdominal organs than the 1.5% preparation. However, little difference in artifacts was found between them. The artifacts tended to be intensified when barium migrated toward the distal portion of the small intestine. Judging from these results, a 2.0% fine particle preparation appeared to be suitable for examination of the upper abdominal organs. For organs in the pelvic region, preparations with a lower concentration were considered suitable.