Non-contrast CT vs CT Angiogram Brain

[waterski232002]

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1) What is the best first study to order in the Emergency Department when you suspect a Posterior circulation ischemic event? It is my understanding that A non-contrast head CT with thin cuts through the posterior fossa is the ideal first study to r/o hemorrhage, etc. Then later they can get an MRI/MRA. Is there any utility in just skipping to a CT Angiogram of the Brain?

2) On another note, is a CT angiogram of the brain any better at picking up a SAH than a non-contrast head CT? If so, how much does in increase the sensitivity?

 

[f_w]

1) It is my understanding that A non-contrast head CT with thin cuts through the posterior fossa is the ideal first study to r/o hemorrhage, etc. Then later they can get an MRI/MRA. Is there any utility in just skipping to a CT Angiogram of the Brain?

CTA is faster and more readily available than MRA at most institutions. If you have facilities to do intraarterial lysis, the CTA can give you the information your INR needs to decide whether he should go ahead.

2) On another note, is a CT angiogram of the brain any better at picking up a SAH than a non-contrast head CT? If so, how much does in increase the sensitivity?

The detection of the bleed itself is dependent on the non-contrast portion of the study, no difference here. But given that 80+% of SAHs come with one or more aneurysms, the CTA is going to give you valuable information for further treatment (coilable vs. butchery).

 

[waterski232002]

CTA is faster and more readily available than MRA at most institutions. If you have facilities to do intraarterial lysis, the CTA can give you the information your INR needs to decide whether he should go ahead.

But this is true for any ischemic stroke patient that presents within the 6 hr window of IA lysis, correct? So that is not specific to enhancing visualization of the posterior fossa.

Just to be clear... if a patient complains of 24 hours of vertigo, ataxia, diplopia, vomiting (lysis is not an option)... is a Non-Contrast CT just as good as CTAngiogram?

 

[colbgw02]

IMHO, if your ER is anything like my hospital's ER, then a "screening" non-contrast CT of the head should be the first study ordered for pretty much any suspected intracranial pathology.

 

[waterski232002]

Would anyone else like to weigh in.... what study is better... Non-contrast CT or CT angiogram? Or are they the same at visualizing the posterior fossa?

 

[f_w]

Unless you do CT perfusion, the CTA is not going to 'show' you the CVA any better than the NCCT if that is what you mean.

The study of choice for anything posterior fossa is of course MRI. The software platforms to run CT and MRI scanners of the same manufacturers have somewhat converged. Many institutions cross-train their CT techs these days so they can do basic MRI work like heads. So if you have a magnet on-site, you may be able to get an MRI during off-hours if you describe a nice enough posterior fossa neurology.

 

[Docxter]

All CTAs include a non-contrast CT as part of the exam. CT and CTA evaluate different things. The actual CTA part is only for looking at the vessels. So, the question as to whether one is better or the other in evaluating the posterior fossa parenchyma is rather irrelevant.

For SAH: They are the same.

For posterior fossa parenchymal lesion, e.g. stroke, they are the same.

CTA looks at the vessels.

If you suspect a posterior fossa/brainstem stroke, you need an MRI. Yes, CT will pick up a proportion of them, but not nearly as sensitive as MRI. And, if you really suspect a brainstem stroke or basilar artery thrombosis, (not like in our ER where every dizzy patient gets an MR/MRA to "r/o vertebrobasilar insufficiency"), neurology should already have been involved.