Imaging description

Intracranial saccular (berry) aneurysms are common intracranial vascular lesions with an estimated prevalence in the general population ranging from 2% to 6% [1]. Digital subtraction angiography (DSA) has the highest spatial resolution of all vascular imaging studies and remains a gold-standard technique. However, while DSA is the most sensitive for such detection and characterization of aneurysms, it is not practical as a screening tool because of its invasive nature and a small risk of neurologic complications.

The sensitivity of CTA has continued to increase, with some studies reporting it to be even comparable to that of DSA [1]. Images are generally reconstructed in 2D maximum intensity projection (MIP) or 3D volume rendering (VR) (Fig. 7.1). The sensitivity and specificity are reported to be as high as 90%, but depend on the size of the aneurysm. According to Villablanca et al., CTA has >90% sensitivity for aneurysms of the middle cerebral artery, regardless of the size of the aneurysm [2]. However, CTA may not clearly identify small aneurysms in the area of the carotid siphon and paraclinoid region.