A More Advanced Case

In this patient, thrombus had formed on a plaque in the basilar artery, at the point where it branches to form the posterior cerebral artery. 

Here is an angiogram in which an iodinated dye was injected into one vertebral artery. The dye fills the injected vertebral artery and has been carried into the basilar artery. However, dye seems to stop at the place where the basilar artery branches.  It looks like the basilar just ends! 

If you look at the CT scan of this patient at the corresponding level, the bright spot at the arrow is actually the thrombus.At the time this patient had this CT scan he had an occluded basilar artery and showed major neurologic deficits. 

This is his CT scan at a level that includes regions of the occipital lobes that are supplied by the basilar branches that have been blocked. The white spots in his ventricles are calcified regions of choroid plexi.

Question

Do you see any abnormality here?

Answer

No.  Even a trained neuroradiologist would not see anything abnormal here.

Now look at the next CT scan which is a similar level but was taken 36 hours later. 

Remember that the basilar artery branches that have been blocked supply parts of both occipital lobes. At 36 hours after the vascular occlusion, can you now identify areas of ischemia?