​Intracranial saccular or berry aneurysms are acquired vascular lesions consisting of thinned out-pouching of the arterial swall. 

Subarchnoid hemorrhage (SAH) is the most frequent sign of the aneurysm rupture.

CTA is a minimally invasive technique, less expensive, easy, quick, and often provides correct information on the presence like dimensions and anatomical location of a cerebral aneurysm. The volumetric acquisition allows the neuroradiologist to obtain oblique, axial, and para-axial views for better display of the dome and neck of an aneurysm, but a baby aneurysm (smaller than 3 mm) can often be missed by CTA.

Digital subtraction angiography (DSA) is the gold standard technique for detecting cerebral aneurysms. It provides high spatial resolution and yields optimal information on aneurysm location, size (dome and neck), collateral artery originating from the dome, and relation between the parent artery and surrounding vascular structures.

DSA remains strongly indicated in

• SAH with a negative CTA
• Discrepancy between the distribution of SAH and displayed aneurysm on CTA
• Doubtful cases of CTA showing a small aneurysm
• CTA with suboptimal quality
• Evaluation of giant aneurysms to obtain hemodynamic information
• Evaluation of an aneurysm very close to bone structures
• Evaluation of SAH due to dissecting aneurysms
• Evaluation of the relationships between the aneurysmal sac and the arteries surrounding or originating from the sac

DSA is mandatory before endovascular treatment.

10-20% of angiography examinations fail to find an aneurysm in cases of subarachnoid hemorrhage. If DSA is negative, repeat examination in 1 to 6 weeks may be considered.

Special thank to Dr. Norraseth, neuro-interventional radiologist.