Sensitivity of Quantified Intracranial Aneurysm Geometry to Imaging Modality.

The objective of this study is to assess the sensitivity of intracranial aneurysm geometry to the modality of imaging. Four imaging modalities-3D rotational angiography (3DRA), computed tomography angiography (CTA), contrast enhanced magnetic resonance angiography (CE-MRA), and time-of-flight magnetic resonance angiography (TOF-MRA)-were assessed using data from a flow phantom and human subjects. A silicone flow phantom of the head and neck arteries with a 10 mm ACOM aneurysm was imaged using all four modalities under steady flow conditions. Three human subjects with mid to large sized intracranial aneurysm who had a 3DRA scan and one of CTA, CE-MRA, or TOF-MRA performed within a day were also studied. The aneurysm and contiguous vasculature were segmented for all available scans and geometric measures of their size (5 indices) and shape (6 indices) were estimated and compared. Visually, the size and shape of segmented 3D models of the aneurysms were similar across scan modalities for both the human subjects and the flow phantom. Consequently, the computed indices were consistent across modalities in the key morphometric indices. In conclusion, quantified indices of 3D geometry of the mid to large sized intracranial aneurysms investigated in this small study population are not sensitive to scanning modality.