New insights of the adaptation of flow diverters to the local geometry of vessel in the treatment of intracranial aneurysms.

Purpose: It is unclear how flow diverters (FDs) and vessels interact in the treatment of intracranial aneurysms. In this study, we examine the local changes in artery and device morphology caused by their mutual interaction.

Methods: Pre-treatment 3DRA and post-treatment XperCT or DynaCT images were collected retrospectively from 25 patients. Vessel anatomies and FD models were obtained by segmenting the corresponding images. Perpendicular cross-sections of vessels and FDs were extracted and described in terms of area, perimeter, and circularity. The geometrical parameters from each vessel were paired point-by-point with those from FDs.

Results: FD cross-sections are typically circular, regardless of the vessel's morphology. The area and perimeter of FD cross-sections were smaller than those of the vessel in 66.8% of the data; however, they were larger in 30.1%, suggesting that the vessel is radially stretching to accommodate the FD expansion. In 3.1% of the slices, the FD area was larger than the vessel, but its perimeter was smaller, indicating a change in the shape of the artery.

Conclusions: Expansion of FD is generally restricted by the morphology of the vessel, but the vessel is also able to adapt to the device by changing its shape or stretching.