Nonradioactive iodoantipyrine enhanced cranial computed tomography: preliminary observations

Nonradioactive 4-iodoantipyrine, an iodinated indicator that freely diffuses across the blood-brain barrier, was serially imaged in vivo using computed tomography (CT). Prominent enhancement was immediately detected in the brain substance of the dog following the intracarotid injection of this contrast medium. An estimate was made of the brain:blood partition coefficient for 4-iodoantipyrine from the CT derived arterial and brain concentration of this iodinated marker. Practical applicability of this technique is limited unless an improved method for getting the 4-iodoantipyrine into solution can be developed. However, this study reinforces the concept that local cerebral blood flow and metabolism can be analyzed by diffusible tracers using CT.