Comparative evaluation of metrizamide and meglumine ioxithalamate in angiography of the vessels of the head and neck.

Metrizamide, a non-ionic contrast medium of low osmolality was compared with meglumine ioxithalamate, the ionic angiographic contrast medium currently in use in our department in a double-blind study. Criteria upon which the comparison was based were: 1) the pain reaction of the patient upon intra-arterial contrast injection, 2) bradycardial reactions upon common carotid injection and 3) the quality of the contrast image. Metrizamide induced significantly less painful sensations than meglumine ioxithalamate in those vessels in which injections of contrast medium are frequently painful (external carotid artery, vertebral artery). No significant difference in the degree of bradycardia was caused by the two contrast media. The degree of bradycardia was also found to be poorly reproducible upon successive injections of the same contrast medium in the same patient, thus raising questions as to the suitability of this method for determining the toxicity of the contrast medium. The quality of the angiograms obtained did not differ significantly with the two media. Spasm, when it occurred during selective external carotid injections, was found to be independent of the contrast agent used, being correlated instead with the depth of distal advance of the catheter tip into the external carotid. Of the 51 patients included in the study, two patients suffered transient neurological deficit after angiography with metrizamide, and one patient suffered a permanent hemiplegia after angiography with meglumine ioxithalamate.