Size and location of ruptured and unruptured intracranial aneurysms measured by 3-dimensional rotational angiography

Abstract 

Objective

The aim of the study was to report about accurate size and location of a consecutive series of ruptured and unruptured aneurysms taking the complex 3-dimensional (3D) anatomy and parent vessel morphology into consideration by using the newly developed 3D rotational angiography (3D-RA).

Methods

One hundred eighteen consecutive patients with 155 saccular intracranial aneurysms were included in the study and received 3D-RA reconstructions for measurement of maximal height and width of the aneurysmal sac. Statistical evaluation compared values for ruptured (n = 83) and unruptured (n = 72) aneurysms.

Results

Mean height and width of unruptured aneurysms were 5.7 and 5.7 mm; of ruptured aneurysms, 6.7 and 6.1 mm (not significant, P = .7 for height and P = .9 for width). The majority of ruptured aneurysms, 81.9% and 59%, were smaller than 10 and 7 mm; likewise, 81.9% and 68.1% of unruptured aneurysms were smaller than 10 and 7 mm. The difference in frequency of small (<10/<7 mm) aneurysms between unruptured and ruptured aneurysms was not significant (P = 1.0 and .32, respectively). The majority (69.4%) of small ruptured aneurysms (<7 mm) were located in the anterior circulation. Most ruptured aneurysms were in the size group 4 to 6 mm in height and 2 to 4 mm in width, and a critical threshold size for aneurysm rupture could not be identified.

Conclusions

An automated calibration procedure applied to all images and excellent visualization of aneurysm and parent vessel morphology using 3D-RA allow accurate size measurement of intracranial aneurysms which may be smaller than previously thought. Small aneurysm (<7 mm), also in the anterior circulation, should be carefully evaluated for treatment.

Abbreviations: 3D-RA, 3-dimensional rotational angiography, CT, computed tomography, CTA, CT angiography, DSA, digital subtraction angiography, H and H, Hunt and Hess grading system for aneurysmal SAH, ISUIA, International Study of Unruptured Intracranial Aneurysms, MCA, middle cerebral artery, RIA, ruptured intracranial aneurysm, SAH, subarachnoid hemorrhage, UIA, unruptured intracranial aneurysm

Keywords: 3D-rotational angiography, Intracranial aneurysm, Aneurysm location, Aneurysm size, Subarachnoid hemorrhage