Hazards of Computerized Tomography

<h3>To the Editor.—</h3> The complications of diagnostic contrast radiography have not been sufficiently emphasized in the neurologic literature despite the fact that both cerebral arteriography and contrast-enhanced computerized axial tomography are frequently employed in the study of much intracranial disease. In addition to the wellknown risk of anaphylaxis, these procedures pose the additional hazards of acute renal failure^1.2(especially in diabetics with elevated serum creatinine levels³), vagal and other neurologic reactions severe enough to cause hypotension,⁴and cardiotoxic abnormalities manifested by disorders of atrioventricular conductivity and automaticity.⁵ Although the pathogenesis of these complications is unknown, prior assessment of risk factors such as azotemia, diabetes, and anemia, or administration of a total dose of contrast material &lt;50 mL/sq m of body surface area, may forestall the appearance of renal failure.³Unifortunately, the risk of overt anaphylaxis is more difficult to calculate, except that severe reactions are