4D Digital Subtraction Angiography for the Temporal Flow Visualization of Intracranial Aneurysms and Vascular Malformations.

Purpose: To assess the benefit and radiation dose of four-dimensional (4D) digital subtraction angiography (DSA) - a time resolved three-dimensional (3D) DSA application - to evaluate the flow and architecture of aneurysms and vascular malformations.

Methods: All patients with cerebrovascular disease were considered who underwent 4D-DSA at our institution between January 2015 and February 2016. For the aneurysm patients, we evaluated the image quality in terms of the visualization of contrast flow in the aneurysm on a 3-point scale (excellent, fair and poor).

Rupture Risk of Small Unruptured Intracranial Aneurysms in Japanese Adults.

Background and Purpose- Therapeutic decision making for small unruptured intracranial aneurysms (<10 mm) is difficult. We aimed to develop a rupture risk model for small intracranial aneurysms in Japanese adults, including clinical, morphological, and hemodynamic parameters. Methods- We analyzed 338 small unruptured aneurysms; 35 ruptured during the observation period, and 303 remained stable.

Evaluation of Balloon Test Occlusion Before Therapeutic Carotid Artery Occlusion: Flat Detector Computed Tomography Cerebral Blood Volume Imaging versus Single-Photon Emission Computed Tomography.

Objective: We aimed to compare flat detector computed tomography cerebral blood volume (FD-CBV) imaging to single-photon emission computed tomography (SPECT) as an adjunctive technique during balloon test occlusion (BTO) in patients with intracranial aneurysms or tumors.

Methods: Twelve patients who underwent SPECT (99mTc-ethyl cysteinate dimer) and FD-CBV imaging during BTO were enrolled. Color-coded cerebral blood flow (CBF) images and color-coded FD-CBV images were generated and visually inspected whether there were asymmetries between the ipsilateral and contralateral cerebral hemispheres.

Combination of high-resolution cone beam computed tomography and metal artefact reduction software: a new image fusion technique for evaluating intracranial stent apposition after aneurysm treatment.

We introduce a new imaging technique to improve visualisation of stent apposition after endovascular treatment of brain aneurysms employing high-resolution cone beam CT and three-dimensional digital subtraction angiography. After performing a stent-assisted coil embolisation of brain aneurysm, the image datasets were processed with a metal artefact reduction software followed by the automated image fusion programmes. Two patients who underwent aneurysm coiling using a Neuroform stent were evaluated.

Accuracy of Length of Virtual Stents in Treatment of Intracranial Wide-Necked Aneurysms.

Background And Purpose: Precise stent deployment is important for successful treatment of intracranial aneurysms by stent-assisted coiling (SAC). We evaluated the accuracy of virtual stents generated using commercial stent planning software by comparing the length of virtual and actually deployed intracranial laser cut stents on three-dimensional digital subtraction angiography (3D-DSA) images.

Methods: We retrospectively analyzed the data of 75 consecutive cases of intracranial wide-necked aneurysms treated with the SAC technique using laser cut stents.

Time-resolved magnetic resonance angiography (TR-MRA) for the evaluation of post coiling aneurysms; A quantitative analysis of the residual aneurysm using full-width at half-maximum (FWHM) value.

Magnetic resonance image (MRI) is now widely used for imaging follow-up for post coiling brain aneurysms. However, the accuracy on the estimation of residual aneurysm, which is crucial for the retreatment planning, remains to be controversial. The purpose of this study is to evaluate a new post-processing technique that provides improved estimation of the residual aneurysm after coil embolization.

Hemodynamics and coil distribution with changing coil stiffness and length in intracranial aneurysms.

Purpose: The purpose of this study was to investigate hemodynamics and coil distribution with changing coil stiffness and length using the finite element method (FEM) and computational fluid dynamics (CFD) analysis.

Methods: Basic side-wall and bifurcation type aneurysm models were used. Six types of coil models were generated by changing the coil stiffness and length, based on commercially available embolic coils.

A new combined parameter predicts re-treatment for coil-embolized aneurysms: a computational fluid dynamics multivariable analysis study.

Purpose: Coil embolization is a minimally invasive method used to treat cerebral aneurysms. Although this endovascular treatment has a high success rate, aneurysmal re-treatment due to recanalization remains a major problem of this method. The purpose of this study was to determine a combined parameter that can be useful for predicting aneurysmal re-treatment due to recanalization.

Effect of catheter positions on hemodynamics and coil formation after coil embolization.

Coil embolization using a micro catheter and coils is one of the most popular surgical methods used for treating intracranial aneurysms. Surgeons need to better understand the effects of changing catheter position because this is under their control during operations. In this study, we simulate coil embolization for a basic bifurcation-type aneurysm using finite element method and computational fluid dynamics.

Relationships between geometrical parameters and mechanical properties for a helical braided flow diverter stent.

Background: Although flow diversion is a promising procedure for aneurysm treatment, the safety and efficacy of this strategy have not been sufficiently characterized. Both mechanical properties and flow reduction effects are important factors in the design of an optimal stent.

Objective: We aimed to clarify the contributions of strut size and pitch to the mechanical properties (radial stiffness and longitudinal flexibility) and geometric characteristics (porosity and pore density) related to flow reduction effects.

Hemodynamic effects from coil distribution with realistic coil models in an aneurysm.

Because of its minimal invasiveness, coil embolization has become a popular way to treat aneurysms. The main problem with this method, however, is the poor understanding of the hemodynamics in the aneurysm after coil embolization. To improve this situation, we used a finite element method and computational fluid dynamics to investigate how hemodynamic parameters depend on the spatial distribution of coils.

Verification of a research prototype for hemodynamic analysis of cerebral aneurysms.

Owing to its clinical importance, there has been a growing body of research on understanding the hemodynamics of cerebral aneurysms. Traditionally, this work has been performed using general-purpose, state-of-the-art commercial solvers. This has meant requiring engineering expertise for making appropriate choices on the geometric discretization, time-step selection, choice of boundary conditions etc.

Selection of helical braided flow diverter stents based on hemodynamic performance and mechanical properties.

Background: Although flow diversion is a promising procedure for the treatment of aneurysms, complications have been reported and it remains poorly understood. The occurrence of adverse outcomes is known to depend on both the mechanical properties and flow reduction effects of the flow diverter stent.

Objective: To clarify the possibility of designing a flow diverter stent considering both hemodynamic performance and mechanical properties.

Variability of hemodynamic parameters using the common viscosity assumption in a computational fluid dynamics analysis of intracranial aneurysms.

Background: In most simulations of intracranial aneurysm hemodynamics, blood is assumed to be a Newtonian fluid. However, it is a non-Newtonian fluid, and its viscosity profile differs among individuals. Therefore, the common viscosity assumption may not be valid for all patients.

Computational fluid dynamics analysis of tandem carotid artery stenoses: Investigation of neurological complications after carotid artery stenting.

Background: Combined extra- and intracranial carotid artery stenoses, particularly involving multiple lesions, show complex hemodynamic properties and represent a therapeutic dilemma. We used computational fluid dynamics (CFD) to investigate whether insufficient cerebral blood flow (CBF) in a 70-year-old man with tandem stenoses was the cause of aphasia and right hemiparesis after carotid artery stenting (CAS) of the extracranial stenosis.

Method: Three-dimensional digital subtraction angiography (3D-DSA) was performed before and after balloon angioplasty and CAS in the patient.

Dose reduction in cone-beam CT scanning for intracranial stent deployment before coil embolization of intracranial wide-neck aneurysms.

Purpose: Flat panel detector (FD)-equipped angiography machines are increasingly used for neuro-angiographic imaging. During intracranial stent-assisted coil embolization procedures, it is very important to clearly and quickly visualize stent shape after deployment in the vessel. It is necessary to quickly visualize stents by cone-beam computed tomography (CBCT).