RANT: CT Angiogram

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Charles A. -

This is crap.

Nigel M., Dr -

I would like to disagree with Al on this one. The downside of the CT then CTA algorithm is indeed the likely high number of incidental findings, and subsequent risk of unnecessary neurosurgical/interventional radiology intervention. Al dismisses this, and suggests that neurosurgeons have algorithms to deal with incidental findings of aneurysms, and likens it to an incidental finding of a AAA on CT abdo performed for other reasons. However, a finding of an aneurysm on CT angio is not an incidental finding - it is what the scan is looking for! The problem comes in trying to decide whether the aneurysm is the cause of the headache (with or without a leak) or not.
I think it is reasonable to do a CT as first line - if within 6 hrs and it is negative, then stop. If >6hrs, then discuss with patient re: LP vs CT-A - I agree most will choose CT-A - but then if CT-A shows an aneurysm I think you then still need an LP to show that there is/isn't a leak, before you can treat this as an incidental finding.

Keith A., P.A. -

I agree with Al. The argument with this approach from admittedly very smart people is that we will find to many false negatives. Unfortunately that is the problem with most new technology including d-dimers, etc... The real problem with all these tests and CT angio is a classic example of this is that this our own fault. We take a perfectly reasonable test and approach for a pt with real risk for the disease(subarachnoid hemmorhage caused by aneurysm) and apply poor clinical judgement and order the test on pts with extremely low or worse yet no pre test clinical probabality of having the disease. ex if you scan everyone with a headache with ct/ct angio yes this is a poor approach and will find lots of unrelated aneurysms to the headache in question.

However if you only apply it to people who you are actually worried about(sudden onset maximal intensity headaches, syncope/near syncope with headache, etc..) Then you took a population that finding an aneurym actually has a real chance of meaning something. The real answer is to stop using technology/tests when they are not clinically indicated in the first place.
Lets start taking accountability for our own actions and not blame technology for our own short comings!!!

matthew s. -

Did I get this right?

Al Sacchedi's recipe for SAH:

1. Be scared enough from a patient's symptoms to investigate for subarachnoid haemorrhage (ie a ruptured aneurysm)

2. Find the aneurysm on CTA.

3. Disregard the finding as incidental.

(4. Settle out of court).

Brendon S. -

Curiously we had this last week. Sudden headache, CT at 8hr -ve, no LP done. CT- COW, MRA -ve. LP done day 11 showing xanthochromia. Formal angio showed 2 aneurysms, 3 mm and 4 mm. Discharge diagnosis non aneurysmal SAH with incidental aneurysm. A Lancet 2003 study indicates a <7mm aneurysm has a low risk at 1:1000/yr, as Al suggested. However an initial LP would have sorted it out, and it underscores that imaging can miss things.

JCM, M.D. -

Why not just order both CT/CTA initially, not CTA if CT is negative, since if the CT is positive, the neurosurgeon is going to want a CTA anyway? This keeps you from taking the patient back a second time to CT after waiting for the radiolgist to read the initial CT. And any reason LP should not be mandatory for CTA positive for an aneurysm, to identify whether the headache is due to aneurysm leak?

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