CTA and CT Perfusion

(from Radiology Assistant)

Normal CTA	Once you have diagnosed the infarction, you want to know which vessel is involved by performing a CTA.
	First look at the images on the left and try to detect the abnormality. Then continue reading. The findings in this case are very subtle. There is some hypodensity in the insular cortex on the right, which is the area we always look at first. In this case it is suggestive for infarction, but sometimes in older patients with leukencephalopathy it can be very difficult. A CTA was performed (see next images).
	Now we feel very comfortable with the diagnosis of MCA infarction.
	CT Perfusion (CTP) With CT and MR-diffusion we can get a good impression of the area that is infarcted, but we cannot preclude a large ischemic penumbra (tissue at risk). With perfusion studies we monitor the first pass of an iodinated contrast agent bolus through the cerebral vasculature. Perfusion will tell us which area is at risk. Approximately 26% of patients will require a perfusion study to come to the proper diagnosis. The limitation of CT-perfusion is the limited coverage.
	Studies were performed to compare CT with MRI to see how much time it took to perform all the CT studies that were necessary to come to a diagnosis. It was demonstrated that Plain CT, CTP and CTA can provide comprehensive diagnostic information in less than 15 minutes, provided that you have a good team. In the case on the left first a non-enhanced CT was performed. If there is hemorrhage, then no further studies are necessary. In this case the CT was normal and a CTP was performed, which demonstrated a perfusion defect. A CTA was subsequently performed and a dissection of the left internal carotid was demonstrated.