Acute subarachnoid haemorrhage: is a negative CT angiogram enough?

Area of Science:

• Neuroradiology
• Vascular Neurology
• Diagnostic Imaging

Background:

• Subarachnoid hemorrhage (SAH) is a critical condition often caused by ruptured cerebral aneurysms.
• Cerebral aneurysms require prompt and accurate diagnosis for effective management.
• Computed tomography angiography (CTA) is a widely used non-invasive imaging modality for SAH evaluation.

Purpose of the Study:

• To evaluate the negative predictive value of 16-channel multisection CTA in detecting aneurysms in patients with spontaneous SAH.
• To compare CTA findings against digital subtraction angiography (DSA) as the gold standard.

Main Methods:

• A prospectively collected database of cerebral angiograms was reviewed.
• 200 consecutive patients with SAH who underwent DSA were identified.
• 176 patients who had prior CTA were included; clinical data and reports were correlated.

Main Results:

• DSA confirmed aneurysms in 60% of patients.
• CTA demonstrated 95.2% sensitivity and 93.2% negative predictive value for ruptured aneurysms.
• Five false-negative CTA results occurred; DSA confirmed aneurysms in these cases.

Conclusions:

• CTA's sensitivity and negative predictive value for ruptured aneurysms are imperfect.
• Continued use of DSA is recommended for most patients with negative CTA after SAH.
• DSA may not be routinely necessary for patients with perimesencephalic syndrome and negative CTA.