Effects of intracarotid ionic and non-ionic contrast material on the blood-brain barrier in a rabbit model

Summary A rabbit model was used to assess the effects of intracarotid injections of ionic monomer (meglumine iothalamate), non-ionic monomer (iohexol, iopromide), and non-ionic dimer (iotrol) contrast materials on the blood-brain barrier. The degree of blood-brain barrier damage was assessed qualitatively using Evans' blue dye, and quantitatively by calculating the difference in pertechnetate uptake between injected and non-injected hemispheres. The results showed that the non-ionic dimer, iotrol, had the least effect on the blood-brain barrier, and that although iopromide and iohexol produced greater damage than iotrol, the ionic compound, meglumine iothalamate, caused the greatest disruption to the blood-brain barrier. The implications of these findings are discussed.     

Case report. Malignant change in an intracranial epidermoid cyst

A malignant epidermoid tumor invading the fourth ventricle had histologic features that indicated malignant transformation in a benign epidermoid cyst. The computed tomographic (CT) findings correlated precisely with the histologic features, revealing both pathologic enhancement and a low attenuation zone. The spectrum of described CT findings in intracranial epidermoids is reviewed and contrasted with the appearance encountered in the present case.     

Effect of intravenous contrast material on the integrity of the blood-brain barrier: experimental study

Increasingly large doses of contrast medium have been advocated for enhanced computed tomography. It is assumed that such large intravenous doses, which increase the osmolality of the blood, do not affect the blood-brain barrier in the same way as intracarotid injections of the same solutions. Using a qualitative marker, Evans blue dye, and a quantitative marker, 99mTc-pertechnetate, a study was performed in rabbits to assess the effect of intravenous sodium iothalamate (Conray-420) at a dose of 8 ml/kg on the integrity of the blood-brain barrier. No qualitative or quantitative evidence of disruption of the blood-brain barrier was demonstrated. Since histologic examination was not done, morphologic changes cannot be excluded.     

The effect of intracarotid nonionic contrast media on the blood-brain barrier in acute hypertension.

PURPOSETo determine whether acute hypertension (HT) is a risk factor for damage to the blood-brain barrier in carotid angiography with nonionic contrast media.METHODSAnesthetized rats received intravenous injections of technetium-99m-pertechnetate and horseradish peroxidase. Two groups of rats received metaraminol to raise their blood pressure to between 165 and 190 mmHg peak systolic and then received intracarotid injections of saline or iopamidol. Two other groups remained normotensive and received intracarotid injections of saline or iopamidol. Animals were perfused with a fixative solution and their brains removed. Activity of extravasated Tc-99m-pertechnetate was determined to assess blood-brain barrier breakdown. Brains were then sectioned, treated histochemically to visualize extravasated horseradish peroxidase, and ranked visually according to horseradish peroxidase staining.RESULTSExtravasation of both tracers was significantly greater in the hypertensive group that received contrast media than in the other three groups.CONCLUSIONSAcute hypertension potentiates the blood-brain barrier-damaging effects of nonionic contrast media during carotid angiography in rats.