BACKGROUND AND PURPOSE: Despite several retrospective studies showing the safety and efficacy of transradial access for cerebral angiography, neurointerventionalists are apprehensive about implementing TRA for neurointerventions. This reluctance is mainly due to anatomic factors, technical factors, and a long learning curve (relative to transfemoral access). We present here our experience of TRA transition for cerebral aneurysm embolization. Our aim was to demonstrate the feasibility and safety of radial access for consecutive embolizations of ruptured and unruptured cerebral aneurysms. MATERIALS AND METHODS: We performed a retrospective review of a prospective data base on cerebral aneurysm embolizations. Between April and December 2018, radial access was considered for all consecutive patients referred to our institution for cerebral aneurysm embolization. Technical success was defined as radial access with insertion of the sheath and completion of the intervention without a crossover to conventional femoral access. The primary safety end point was the in-hospital plus 30-day incidence of radial artery occlusion. Secondary end points included intraoperative complications and neurologic complications at discharge and in the following 30 days. RESULTS: Seventy-one patients with a cerebral aneurysm underwent 73 embolization procedures at our institution. The first-choice access route was the radial artery in 62 patients (87.3%) and the femoral artery in 9 (12.6%). Thirty-four embolizations were performed using coils, 22 used a balloon-assisted coil technique, 6 used a stent-assisted coil technique, and 2 used a flow diverter. Crossover to femoral access was observed in 2 patients (3.1%). Four patients developed coil-induced thrombi requiring intra-arterial tirofiban injections. In 1 case, an aneurysm ruptured during the operation but did not have a clinical impact. No cases of radial artery occlusion or hand ischemia were observed. CONCLUSIONS: A transition to radial access for cerebral aneurysm embolization is feasible and does not increase the level of risk associated with the procedure.

BACKGROUND AND PURPOSE: Resistance to blood flow in the cerebral drainage system may affect cerebral hemodynamics. The objective of the present study was to use phase-contrast MRA to quantify resistance to drainage of blood across branches of the venous sinus tree and to determine whether the resistance to drainage values correlated with internal jugular vein outflows. MATERIALS AND METHODS: We performed whole-head phase-contrast MRA and 2D phase-contrast MR imaging in 31 healthy volunteers. Vascular segmentation was applied to the angiograms, and the internal jugular vein velocities were quantified from the flow images. Resistance to drainage across branches of the venous sinus tree was calculated from the segmented angiograms, by using the Poiseuille equation for laminar flow. Correlations between the values of resistance to drainage and internal jugular vein outflow measurements were assessed by using the Spearman ρ. RESULTS: The overall mean resistance to drainage of the venous sinus tree was 24 ± 7 Pa s/cm³. The mean resistance to drainage of the right side of the venous sinus tree was 42% lower than that of the left side (P < .001). There were negative correlations between the values of resistance to drainage and internal jugular vein outflows on both the left side of the venous sinus tree (R = −0.551, P = .002) and the right side (R = −0.662, P < .001). CONCLUSIONS: Phase-contrast MRA is a noninvasive means of calculating the resistance to drainage of blood across the venous sinus tree. Our approach for resistance to drainage quantification may be of value in understanding alterations in the cerebral venous sinus drainage system.

Background: Diffusion tensor imaging (DTI) is a useful tool for assessing changes that occur in microstructures. We have developed a novel method for region of interest (ROI) delineation in the assessment of DTI parameters in patients with normal pressure hydrocephalus (NPH). Purpose: To compare the standard method and our novel method in an evaluation of the impact of surgery on periventricular white matter in patients with NPH. Material and Methods: Ten patients with NPH underwent 3T magnetic resonance imaging (MRI; including 12-direction DTI sequences) before and after surgery. We recorded diffusion parameters (λ_i, the fractional anisotropy [FA], the apparent diffusion coefficient, and D_r) in the internal capsule (IC) and the body of the corpus callosum (BCC). Using the standard delineation technique, regions of interest (ROIs) were positioned according to anatomical and functional considerations and then filled with several sub-ROIs. The ROIs delineated with our novel technique (extracted as the six sub-ROIs with the lowest standard deviation for the FA) were arranged in two rows (medial and lateral), from the ventricle to the brain surface. Results: The within-ROI homogeneity was higher with the novel method than with the conventional method ( P < 10⁻⁴). When the conventional delineation method was applied to the IC data, only λ₂ was found to be significantly greater after surgery; in contrast, application of our novel method evidenced a significant decrease in FA and λ₁ and a significant increase in λ₂ ( P < 0.05). Both before and after surgery, the FA in the medial row of ROIs was greater than the FA in the lateral row ( P < 0.01). In the BCC, only λ₂ and D_r varied significantly (when evaluated with the novel method). Conclusion: Our results show that use of a novel method of DTI data analysis may be more sensitive to local changes induced by surgical procedures. Furthermore, this novel method was able to detect the transmantle pressure gradient related to the regional stress distribution.