Fluoroscopy, CT, and MR imaging characteristics of a novel primarily bioresorbable flow-diverting stent for aneurysms

Abstract

Background Five to ten percent of the global population have unruptured intracranial aneurysms, and ruptured brain aneurysms cause approximately 500,000 deaths a year. Flow-diverting stent treatment is a less invasive intracranial aneurysm treatment that induces aneurysm thrombosis. The imaging characteristics of a novel primarily bioresorbable flow-diverting stent (BFDS) are assessed in comparison to the leading metal stent using fluoroscopy, CT, and MRI. Methods X-ray/fluoroscopic images of stents were taken using a human cadaveric skull model. CT and MRI were acquired using silicone flow models of residual aneurysms. Images were analyzed with Likert scales in anonymous surveys by neurointerventionalists. Quantitative measurements of radiographic density (CT) and artifact boundary size (CT & MRI) were also obtained. Results Visibility of the BFDS on X-ray was less than the metal stent but deemed adequate for deployment and intraprocedural assessment. The metal stent was more radiopaque than the BFDS on CT, but qualitative assessment was not significantly different for the two stents. MRI imaging was significantly better using the BFDS in terms of overall artifact and intraluminal assessment. Conclusions The BFDS has adequate visualization on X-ray/fluoroscopy and should be clinically acceptable for fluoroscopic deployment. On MRI, there is less quantitative artifact as well as overall improved qualitative assessment that will allow for more detailed non-invasive imaging follow-up of treated aneurysms, potentially reducing the need for digital subtraction catheter angiography.

Medical Imaging Compatibility of Magnesium- and Iron-Based Bioresorbable Flow Diverters

“…Other groups have investigated the medical imaging compatibility of BRFDs. Morrish et al 11 demonstrated suitable visibility for fluoroscopy-guided device delivery of their primarily polymer-based BRFD. Furthermore, they demonstrated a quantitative reduction in device-induced artifacts in MR imaging and CT images when their BRFD was compared with an FDA-approved control FD.…”

“…BRFDs show promise in reducing metal-induced image artifacts for 2 reasons: First, before any resorption, the innate material properties of many bioresorbable materials induce fewer metal artifacts than conventional FD materials. [11][12][13] Second, the progressive and eventual complete resorption reduces device volume and, therefore, metal-induced artifacts with time. 14 We have previously developed BRFDs out of magnesium (MgBRFD) and iron (FeBRFD) alloys.…”

Bioresorbable flow diverters for the treatment of intracranial aneurysms: review of current literature and future directions

“…Reduction in imaging artifacts: follow-up CT and/or MRI is used to evaluate FD performance. The innate properties of many bioresorbable materials reduce imaging artifact relative to conventional FD materials 17. Additionally, progressive reduction in device volume shows promise to further reduce image artifact over time.…”

“…In these regions, thrombus was observed on the abluminal side of the devices via SEM. A separate study by Morrish et al assessed the medical imaging characteristics of these nitinol-containing BRFDs relative to industry standard FD controls 17. There was no difference in anticipated visibility during deployment or image quality in fluoroscopy and CT images when qualitatively assessed by eight blinded neuroradiologists.…”