Safety of contrast media in cerebral angiography: iopamidol vs. methylglucamine iothalamate.

A randomized double-blind study was performed in 27 patients to compare the clinical safety, incidence of pain and warmth, and film quality produced by iopamidol and Conray-60 in selective cerebral angiography. No complications or adverse reactions occurred in either group. Iopamidol was significantly less painful than was methylglucamine iothalamate for common carotid artery injections and caused significantly less heat in both common carotid and internal carotid artery injections. Film quality and diagnostic accuracy were excellent in both groups. These results, when viewed in conjunction with laboratory data demonstrating the decreased neurotoxicity of nonionic contrast agents, suggest that iopamidol is an important advance in the development of angiographic contrast media.

CT scanning phantom for normalization of infant brain attenuation.

The x-ray attenuation values of brain studied with computed tomography (CT) are strikingly affected by the ages of the subjects. Premature neonates, for example, may have brain attenuation values 20-30 H below adult values. These lower attenuation values for developing compared with adult brain can be ascribed partly to machine-related effects (beam-hardening, adult algorithms, scanning geometry, etc.). A scanning phantom made from aluminum was developed that can be used to develop a nomogram for any particular scanner from which normalized brain attenuation may be derived for any small head size. Using this nomogram, predicted neonatal attenuations are still 10-15 H higher than those actually observed in scanning neonates. The model predicts that, at the most, 3-4 H of this discrepancy can be accounted for by less beam-hardening from the lower bone attenuation of the thinner developing skull. Presumably, the rest is from a lower brain density in neonates (higher water content). By normalizing to cerebrospinal fluid (water) with special care to avoid partial-volume artifacts, one can predict attenuation values for developing brain more accurately.