Radiographic quality and patient discomfort in sialography: comparison of iohexol with iothalamate

We have compared the usefulness of a newly developed, low osmolality contrast medium, Omnipaque 350 (75.49% iohexol, 350 mgI ml-1), for sialography with one of the established, Angioconray (80% sodium iothalamate, 480 mgI ml-1), in a double-blind, prospective randomized clinical trial in 80 patients. The diagnostic quality of the sialograms, pain during the procedure and discomfort subsequently were investigated. There was no difference in either group between the number of sialograms judged as diagnostically useful, although those of excellent quality were significantly more frequent in the Angioconray group. The level of pain on injection of the medium was significantly lower in the Omnipaque group. Eighteen per cent of the patients with Omnipaque had severe or moderate pain on injection of the contrast medium, while 63% had such pain with Angioconray. There was no difference in postprocedural discomfort between the two contrast media. We concluded that the low osmolality contrast medium is more favourable for sialography despite its lower iodine content.