What are the indications for CT angiography (CTA) in hemorrhagic cerebrovascular accident (CVA)?

CT Angiography in Hemorrhagic Stroke: Key Indications

CT angiography should be performed in hemorrhagic stroke to identify underlying vascular causes such as aneurysms, arteriovenous malformations, and other structural lesions, with sensitivity and specificity exceeding 90% for detecting these culprit vascular abnormalities. 1

Primary Indications for CTA

Identifying Underlying Vascular Pathology

• CTA is indicated to detect aneurysms and arteriovenous malformations as the underlying cause of intracerebral hemorrhage, with reported sensitivity of 96.5% for aneurysms of all sizes and 98.4% for aneurysms >3mm 1
• Perform CTA when hemorrhage location or characteristics suggest a non-hypertensive cause, including lobar hemorrhages, superficial hemorrhages, or hemorrhages in younger patients without hypertension 1
• CTA effectively identifies vascular malformations with sensitivity and specificity exceeding 90% compared to catheter angiography 1

Specific Clinical Scenarios Requiring CTA

Subarachnoid hemorrhage component: When blood is present in the subarachnoid space or sylvian fissure, CTA is essential to identify underlying aneurysms 1

Atypical hemorrhage locations:

• Isolated intraventricular hemorrhage without obvious cause 1
• Blood in unusual locations suggesting vascular abnormality 1
• Hemorrhages with atypical distributions not matching typical hypertensive patterns 1

Young patients or absence of hypertension: The yield of angiography is highest in younger patients without traditional risk factors for hypertensive hemorrhage 1

Abnormal imaging features on initial CT:

• Abnormal calcifications suggesting vascular malformation 1
• Obvious vascular abnormalities visible on non-contrast CT 1
• Edema disproportionate to hemorrhage age 1
• Unusual (non-circular) hematoma shape 1

Prognostic Assessment

• CTA spot sign detection helps predict hematoma expansion risk, which is associated with clinical deterioration and poor outcomes 1
• The presence of contrast extravasation within the hematoma on CTA or contrast-enhanced CT identifies patients at high risk for continued bleeding 1

When CTA May Not Be Necessary

Typical hypertensive hemorrhage pattern: In elderly patients with hypertension and deep hemorrhage (basal ganglia, thalamus, pons, cerebellum) in typical locations, the yield of CTA is lower 1

However, even in these cases, CTA can help determine appropriate disposition since some facilities cannot manage all ICH types 1

Alternative and Complementary Imaging

MRA as Alternative

• MRA provides comparable sensitivity (95%) and specificity (89%) to CTA for aneurysm detection without radiation exposure 2
• MRA with sensitivity and specificity exceeding 90% can detect intracranial vascular malformations 1
• MRA is superior for detecting cavernous malformations, which are angiographically occult 1

When to Proceed to Catheter Angiography

• Catheter angiography remains the gold standard when CTA/MRA are inconclusive or show findings requiring detailed characterization before intervention 1, 2
• Consider catheter angiography when clinical suspicion remains high despite negative non-invasive imaging 1
• Timing of angiography should balance diagnostic need with patient stability—critically ill patients may require urgent surgery before angiography, while stable patients should undergo angiography before intervention 1

Important Caveats

Contrast-enhanced CT limitations: Standard contrast-enhanced CT is not helpful for typical hypertensive hemorrhage follow-up unless metastatic disease is suspected and MRI is not feasible 1

Metal artifact interference: CTA has limited utility for post-treatment surveillance when metallic coils, clips, or stents cause streak artifacts 1, 2

Small aneurysm detection: CTA sensitivity decreases for aneurysms <3mm or those adjacent to bone 1, 2

Pediatric considerations: In children, 48% of hemorrhagic strokes are due to arteriovenous shunts, making vascular imaging particularly important 1

Practical Algorithm

1. All hemorrhagic strokes: Begin with non-contrast CT to confirm hemorrhage 1

2. Proceed to CTA if any of the following:

   • Subarachnoid blood component 1
   • Age <60 years without hypertension 1
   • Lobar or superficial location 1
   • Unusual hemorrhage location or shape 1
   • Disproportionate edema 1
   • Need to assess hematoma expansion risk 1

3. Consider MRA instead of CTA when radiation avoidance is priority or when evaluating for cavernous malformation 1, 2

4. Reserve catheter angiography for cases requiring definitive characterization before treatment or when non-invasive imaging is inconclusive 1, 2