<p>Intravascular injection of iodixanol opacifies vessels in the path of flow of the contrast agent, permitting visualization of internal structures. In imaging of the body, iodinated contrast agents diffuse from the vascular into the extravascular space. In a normal brain with an intact blood-brain barrier, contrast does not diffuse into the extravascular space. In patients with a disrupted bloodbrain barrier, contrast agent accumulates in the interstitial space in the region of disruption.</p>