Barium contrast agents

Trends in contrast media research the last 100 years

This review focuses on the trends in contrast media (CM) research published in Acta Radiologica during the last 100 years, since the first edition in 1921. The main topics covered are the developments of iodine- and gadolinium-based CM. Other topics include manganese-based CM for magnetic resonance imaging (MRI) and barium for the investigation of the alimentary tract. From a historic point of view, special CM for use in cholegraphy and myelography are addressed in the review. Today, these imaging procedures are obsolete due to the development of computed tomography, MRI, and ultrasound. The historical use of radioactive thorium-based CM for angiography is also addressed. Furthermore, publications on adverse reactions to CM are reviewed.

A new bone vascular perfusion compound for the simultaneous analysis of bone and vasculature

Bone is a highly vascular tissue, which plays an important role in bone development and healing. The ability to analyze both the bone and vasculature simultaneously can enhance the understanding of wound healing, development, and disease in bone. At present, analysis methods are limited in their ability to allow for this simultaneous analysis of bone and bone vasculature in three dimensions, without using the most recent dual-energy computed tomography (CT) techniques. In this study, we present a new barium sulfate (BaSO(4)) radiopaque vascular perfusion compound for performing postmortem microangiography with single-beam microcomputed tomography (microCT), which allows for such simultaneous analysis. This compound differs from currently available contrast mediums due to (1) the high weight-to-volume ratio of BaSO(4) achieved, (2) small BaSO(4) aggregate size (<5 microm), (3) minimal additives, and (4) its miscibility with blood and saline. Most notably, it achieves a radiodensity of 2.4x that of cortical bone, with high perfusion of both the arterial and venous systems and the intervening capillary bed, resulting in an in vivo radiodensity that ranges from that of bone to titanium. Our results, verified using a rat femoral gap-healing model, show that the compound is uniquely suited to high-contrast imaging of the vasculature in the presence of undecalcified bone, with a versatility to be used in other tissues.

Revisiting oral barium sulfate contrast agents

Oral contrast agents used during CT colonography (CTC) are valuable and may reduce false positive and false negative detections due to stool and residual fluid. Electronic cleansing algorithms are feasible, and oral contrast agents can eliminate the CTC requirement for a clean colon. Recent work shows oral contrast frequently adheres to polyps, with a preference for those with villous histology, a characteristic of advanced polyps. This finding encourages the development of contrast agents that highlight polyps at greatest risk for progression to malignancy. Our review summarizes numerous aspects of oral barium sulfate contrast agents as well as tests to assess adherence and coating ability of the agents, offering arenas to explore and tools for evaluation.

The effect of oral magnesium-containing bowel preparation agents on mucosal coating by barium sulphate suspensions

Alteration in the quality of mucosal coating by barium sulphate suspension observed during double-contrast barium enema (DCBE) examinations when an oral magnesium-containing purgative (Picolax) was used as sole bowel preparation has been investigated in vivo. Small amounts of Picolax were found to produce a linear increase in apparent viscosity and thixotropy, due to flocculation. The effect of equivalent concentrations of acid was significantly less (p less than 0.01), and of magnesium chloride was significantly greater (p less than 0.05), whereas magnesium citrate was comparable to Picolax, demonstrating the deflocculating effect of citrate on the flocculating action of magnesium ions. It is suggested that colonic residue from orally ingested magnesium-containing purgatives may contain sufficient magnesium ions to increase viscosity of the barium suspension and visibly affect its coating during DCBE.

Scanning electron microscopy of the spreading of barium sulfate suspensions on the gastric mucosa of the rat. Effect of wetting agents, bile salt and lecithine

Scanning electron microscopy was performed on the rat stomach mucosa after application of BaSO4 and three barium-containing commercial contrast media. The degree of flocculation was assessed; flocculation could be prevented by using synthetic wetting agents and by physiologic, natural emulsifiers, sodium taurocholate and lecithine.

In vivo and in vitro assessment of barium sulphate suspensions

In vitro methods of testing the efficiency of barium sulphate suspensions in delineating mucosal detail using canine cadaveric stomachs have been described in the literature. In this study a comparison is made between in vitro and in vivo tests in the stomach and small intestine of dogs, using several brands of barium sulphate. The results indicate that there is considerable variation in the behavior of these suspensions between the in vitro and in vivo tests particularly in the stomach. It is our view that in vitro tests of this sort are of little value for assessing the relative advantages and disadvantages of these suspensions in demonstrating mucosal detail.

Observations on the behaviour of barium sulphate suspensions in gastric secretion

A number of barium sulphate suspensions showed varying patterns of stability when provoked with gastric secretion. The stability of the suspensions was affected by the pH, the mucin content and the volume of secretion used. These studies indicate that flocculation of the suspension in the presence of gastric residue decreases as the amount of undiluted barium sulphate in the mixture is increased.

Physical characteristics of barium contrast media and their influence on roentgen image information

Various barium contrast media intended for radiographic examinations of the colon were analysed in a plastic model. This model contained fixed test objects which could be identified and counted on the films thus providing a measure of image information obtainable. Particular attention was paid to the marked differences in sedimentation of the various contrast media and the manner in which these affected image information.