title: High density barium sulfate suspension for MRI: optimization of concentration for bowel opacification.
abstract: In this in vitro study of a potential oral MRI contrast agent, barium sulfate suspension (BSS), the object was to examine the effect of varying barium sulfate concentration on signal intensity while keeping suspension additives the same; and to optimize the concentration of a specific preparation of BSS. A phantom was used to test suspensions with concentrations of barium sulfate ranging from 90% to 220% w/v. T1-weighted, T2-weighted, and gradient echo sequences all showed a decrease in signal as concentration was increased to 170%. Between 170% and 220%, the signal intensity was constant on the T1-weighted and T2-weighted sequences. With the proton density and gradient echo sequences, there was a slower rate of decline in the signal intensity in the 170 to 220% range of BSS concentrations. We conclude that BSS with a concentration in the range of 170% to 220% w/v is optimum for the specific preparation used. We speculate that the behavior of the signal-to-noise ratio with changing concentration is explained by factors including proton density, T1 relaxation enhancement, diffusion effects, and magnetic field inhomogeneity, depending on the particular pulse sequence used.
authors.affiliation: Department of Radiology, University of Florida, Gainesville 32610.
authors.forename: J R
authors.initials: JR
authors.lastname: Ballinger
authors.forename: P R
authors.initials: PR
authors.lastname: Ros
mesh_terms: D000284:Administration, Oral; D001466:Barium Sulfate / Q000008:administration & dosage*; D004064:Digestive System / Q000473:pathology*; D066298:In Vitro Techniques; D008279:Magnetic Resonance Imaging; D008747:Methylcellulose; D008961:Models, Structural; D013535:Suspensions; D014867:Water
chemical_list: D013535:Suspensions; D014867:Water; D001466:Barium Sulfate; D008747:Methylcellulose