Niclas Schmitt

Purpose: Mechanical thrombectomy (MT) is the first-line therapy for patients with acute ischemic stroke due to large vessel occlusion; however, despite substantial advances in MT techniques and devices, mechanical recanalization remains unsuccessful in up to 15% of patients. Intracranial rescue stenting represents a promising option to achieve successful recanalization and good clinical outcomes in patients with failed MT. Methods: In this retrospective, observational single-center analysis 77 consecutive patients who underwent failed MT and a maximum of 4 unsuccessful device passes were included. The ACCLINO flex stent / CREDO ^® heal stent were used in 38 / 39 patients. The study endpoint was a clinically favorable outcome defined as mRS ≤ 3 at 90 days. Results: A clinically favorable outcome was achieved in 64.1% (25/39) of patients treated with the CREDO heal stent and in 39.5% (15/38) of patients treated with the ACCLINO flex stents ( p = 0.031). Rescue stenting with the CREDO heal stent (aOR 3.51 95% CI 1.11–11.13, p = 0.033), baseline NIHSS (aOR 0.97 95% CI 0.85–0.97, p = 0.005) and pmRS (aOR 0.52 95% CI 0.31–0.89, p = 0.016) were independently associated with a favorable clinical outcome. Baseline characteristics did not differ between both groups. Conclusions: This study suggests that the design of the implanted stent device may influence the clinical outcome. Features such as optimized radial force and thrombogenicity-reducing surfaces of stents used for RIS may improve clinical outcomes of patients treated with intracranial rescue stenting in unsuccessful MT. These findings are hypothesis-generating and require confirmation in prospective, randomized studies.

Background: Flow diverters have expanded endovascular treatment options, yet large real-world data about their comparative periprocedural safety in the treatment of unruptured intracranial aneurysms are limited. This study aimed to compare the short-term safety of flow diverters with alternative endovascular techniques. Methods: We analyzed 24 458 procedures for unruptured intracranial aneurysms recorded in the DEGIR (Deutsche Gesellschaft für Interventionelle Radiologie und minimal-invasive Therapie) endovascular registry between January 2018 and December 2025, across 154 German centers. A 1:1 propensity score-matched cohort was derived. The primary outcome was any periprocedural complication within 72 hours. Secondary outcomes were severe complications (permanent neurological deficit or death), hemorrhagic complications, and thromboembolic complications. Temporal trends were assessed using the interaction between flow diverter treatment and treatment year. ORs and 95% CIs are reported. Results: We included 13 576 (6788 flow diverter, 6788 non-flow diverter) 1:1 propensity score-matched procedures in our analysis. Flow diverter treatment was not associated with a significant difference in overall (OR 1.09, 95% CI 0.94 to 1.26), thromboembolic (0.99, 0.81 to 1.21), hemorrhagic (1.30, 0.99 to 1.70), or severe complications (1.38, 0.94 to 2.02). No significant temporal trend was observed for any of the outcomes. Results were robust in sensitivity analyses comparing flow diverters with stent-assisted coiling and restricting the cohort to saccular aneurysms. Conclusions: In a large national quality assurance registry, flow diverter treatment for unruptured intracranial aneurysms was not associated with a significant increase in periprocedural (≤72 hour) complication risk.

Background: Flat-detector computed tomography (FDCT) is increasingly used for peri-interventional cerebral imaging but is associated with a relatively high radiation exposure. Copper (Cu) filtration may reduce radiation dose. However, its impact on cerebral image quality and intracranial hemorrhage detection remains unclear. Methods: In this retrospective single-center study, 31 patients undergoing neurointerventional procedures with intraindividual FDCT acquisitions with and without Cu filtration were analyzed. Quantitative image quality was assessed using contrast-to-noise ratio (CNR). Qualitative image analysis and intracranial hemorrhage detection were independently evaluated by two readers blinded to Cu filtration status using five-point scales. Results: Cu filtration resulted in a significant radiation dose reduction of 25.9% for both entrance skin dose (145.19±13.18 mGy vs 195.89±18.05 mGy) and dose-area product (41.52±3.77 Gy·cm² vs 56.01±5.16 Gy·cm²), respectively (P<0.001). No differences in CNR were observed for unfiltered vs Cu-filtered FDCT (basal ganglia: 4.73±2.04 vs 4.37±1.99, P=0.419). Qualitative image ratings were similar between techniques (supratentorial cortex: 2.27±0.66 vs 2.08±0.75, P=0.089), with very good inter-reader agreement (κ=0.86; 95% CI: 0.80 to 0.91). All intracranial hemorrhages were correctly identified by both techniques. Correct exclusion of intracranial hemorrhage was 15/16 with Cu filtration and 14/16 without Cu filtration, without statistically significant difference. Differences were limited to hemorrhage mimics (n=2) and minor variations in diagnostic confidence without affecting binary classification. Conclusion: Cu filtration in cerebral FDCT enables substantial radiation dose reduction while preserving image quality and intracranial hemorrhage detection, supporting its clinical implementation as a practical dose optimization strategy for peri-interventional imaging.

Background: Flat-detector computed tomography (FDCT) is increasingly used for periinterventional cerebral imaging. The recently introduced Sine Spin FDCT (S-FDCT) aims to improve cerebral soft tissue contrast compared with conventional FDCT (C-FDCT). Reliable visualization of healthy brain parenchyma is essential for detecting pathological changes. This study compared gray–white matter differentiation between intraindividually acquired S-FDCT and C-FDCT. Methods: A retrospective analysis of a prospectively maintained database included patients with ischemic stroke treated by mechanical thrombectomy who underwent both S-FDCT and C-FDCT within the same interventional session on a latest-generation angiography system. Quantitative image quality was assessed using the contrast-to-noise ratio (CNR). Qualitative image quality was evaluated using a five-point scale at basal ganglia and supratentorial cortex. Analyses focused on healthy brain parenchyma contralateral to infarction. Radiation dose was assessed using entrance-skin dose and dose-area product (DAP). Results: Forty patients (74.2 ± 15.3 years) were analyzed. S-FDCT demonstrated a higher CNR than C-FDCT (mean CNR ± SD: 2.62 ± 1.36 versus 1.03 ± 0.38; p < 0.001). Qualitative ratings were higher for S-FDCT at the basal ganglia (2.45 ± 0.71 versus 1.54 ± 0.53; p < 0.001) and supratentorial cortex (3.01 ± 0.80 versus 1.71 ± 0.60; p < 0.001). Inter-reader agreement was good (κ = 0.798). S-FDCT showed a moderately higher radiation dose than C-FDCT (DAP: 50.6 ± 3.10 versus 46.89 ± 2.86 Gy·cm², p < 0.001). Conclusion: S-FDCT improves cerebral soft tissue visualization compared with C-FDCT in periinterventional imaging. These findings highlight the potential of Sine Spin technology to enhance FDCT image quality and support its role in advanced angiography-suite–based neuroimaging.

Three-dimensional rotational angiography (3D-RA) is a key modality in endovascular neurointerventions but often provides limited visibility of small, clinically relevant vessels such as perforating arteries. This study aimed to evaluate the performance of a novel, dedicated vessel enhancement software in improving vascular visibility in 3D-RA datasets. In this retrospective analysis of a prospectively maintained institutional database, fifty consecutive patients with unruptured anterior circulation aneurysms underwent standardized 3D-RA acquisitions on the ARTIS icono angiographic system (Siemens Healthineers). Each dataset was reconstructed with and without vessel enhancement. Quantitative analysis comprised contrast-to-noise ratio (CNR) measurements in the M1 segment of the middle cerebral artery and in perforating branches. Qualitative image quality was independently assessed by two experienced readers on a five-point scale. Vessel enhancement yielded consistent improvements across all analyses. CNR increased in the M1 segment (mean CNR ± standard deviation (SD), no vessel enhancement (N-VE): 25.15±5.42 vs. VE: 27.85±5.41, p<0.001) and in perforating arteries (mean CNR ± SD, N-VE: 22.26±4.57 vs. VE: 24.80±4.75, p<0.001). Overall qualitative ratings improved from "very good" to "excellent" diagnostic quality, with higher scores for vessel-enhanced reconstructions compared with unenhanced images (mean score ± SD, N-VE: 3.90±0.65 vs. VE: 4.66±0.52, p<0.001). Improvements were particularly evident for the continuity and visibility of fine vascular structures. Inter-reader agreement was good (κ=0.72), supporting the robustness of the findings. Dedicated vessel enhancement software improves the depiction of both larger arteries and small perforating branches in cerebral 3D-RA. By enabling clearer visualization of fine vascular structures, this approach may strengthen diagnostic confidence and procedural safety in complex endovascular neurointerventions.

Objectives: Cerebral angiography remains the gold standard for the diagnosis and endovascular management of cerebral aneurysms. Three-dimensional rotational angiography (3D-RA) provides superior anatomic resolution compared with conventional 2D imaging; however, it is associated with relatively high radiation exposure, raising specific concerns regarding the ocular lens dose. This study aims to evaluate the potential of copper (Cu) filtration for reducing radiation dose in 3D-RA. Materials and Methods: Forty subsequent patients undergoing endovascular treatment of unruptured cerebral aneurysms were included. All received 3D-RA using the ARTIS icono angiography system (Siemens Healthineers). In 20 patients, standard hardware with a 0.8 mm aluminum (Al) filter was applied; in the subsequent 20 patients, the Al filter was replaced by a 0.1 mm Cu filter. Image quality was assessed quantitatively through contrast-to-noise ratio (CNR) and qualitatively using a 5-point scale. Results: There were no differences in image quality between the two groups in the 3D neurovascular native/contrast images, both quantitatively (eg, mean CNR ± SD, Al: 20.72 ± 1.82 vs Cu: 20.66 ± 1.54; P = 0.93) and qualitatively (mean score ± SD, Al: 4.55 ± 0.54 vs Cu: 4.63 ± 0.46; P = 0.75), with excellent image quality achieved in both groups. Total radiation dose was lower with the Cu filter (e.g., mGy ± SD, Al: 110.63 ± 10.75 vs Cu: 68.70 ± 6.03; Gy·cm ² ± SD, Al: 6.26 ± 1.57 vs 3.35 ± 0.67, P < 0.001 respectively), corresponding to a dose reduction of 38% (entrance-skin dose) and 46% (dose-area product). Conclusion: The use of a copper filter in cerebral 3D-RA substantially reduces radiation dose without compromising diagnostic quality, representing a practical advancement in patient safety in 3D-RA. The method integrates seamlessly into existing protocols and can be readily implemented in clinical practice.

Introduction: Mechanical thrombectomy is a highly effective treatment for acute ischemic stroke (AIS) caused by large vessel occlusions (LVO). However, our understanding of the pathophysiology of AIS is still limited, particularly regarding the ischemic microenvironment distal to the occlusion. Aim: To investigate the relationship between the intracerebral blood pressure (BP) distal to an LVO and clinical and imaging parameters. Methods: In this single-center prospective study, intracerebral BPs proximal and distal to the occluding clot were measured during thrombectomy in patients with AIS of the anterior circulation caused by LVO. BPs were correlated with imaging parameters and clinical data using Spearman’s rank correlation and linear regression. Results: 25 patients were included. A significant correlation was found between the mean arterial pressure (MAP) distal to the occlusion and the baseline Alberta Stroke Program Early CT Score (Spearman r=0.503, P=0.014) and baseline National Institutes of Health Stroke Scale score (r=−0.439, P=0.036). No significant correlation was observed between the MAP distal to the occlusion and collateral scores (eg, MAP vs American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology score (r=0.307, P=0.165) or modified Rankin Scale (mRS) score (pre-mRS vs 90-day mRS; r=0.013, P=0.952)). Systemic MAPs did not correlate with the MAP distal to the clot (eg, R ² =0.029, P=0.593). Conclusion: The intracerebral BP measured in the ischemic vasculature distal to the LVO correlates with the extent of the ischemic core and the clinical severity at baseline, but not with collateral scores, systemic BPs, or functional outcome. These results shed light on the pathophysiology of BP mechanisms in AIS and can be the basis for further research in this field.