Christian Mathys

RATIONALE AND OBJECTIVES: 3D-TOF-MRA is a standard non-invasive method for detecting and monitoring intracranial aneurysms, but long scan times remain a limitation. Compressed sensing (CS) acceleration for intracranial aneurysm evaluation has mainly been studied at 3T. This prospective single-center non-inferiority study compared CS-accelerated 3D-TOF at 1.5T with GRAPPA-accelerated 3D-TOF-MRA for evaluating untreated intracranial aneurysms. MATERIALS AND METHODS: Sample size was determined via a preliminary retrospective study. 25 patients with 32 untreated aneurysms underwent both CS- (factor 7, 3:04 min) and GRAPPA-accelerated (factor 2, 5:00 min) 3D-TOF, yielding a 38.7% scan-time reduction. Two blinded neuroradiologists assessed overall image quality (primary endpoint) and artifacts, subjective CNR, aneurysm delineation and diameters (secondary endpoints). Non-inferiority was tested via one-sided t-test (prespecified 10% margin); interrater agreement used ICC. RESULTS: CS demonstrated non-inferiority to GRAPPA for overall image quality in both readers (p ≤ .023), though interrater agreement was low (ICC 0.241–0.262), reflecting subjective variability. Secondary exploratory analyses showed heterogeneous preferences. ROI-based CNR was lower for CS (median 169.6; IQR, 91.0-226. vs. 278.2; 181.0-366.2). Aneurysm diameter measurements showed excellent interrater agreement for both techniques ( CS ICC, 0.899-0.980; GRAPPA ICC, 0.877-0.973; all p < .001). CONCLUSION: CS-accelerated 3D-TOF at 1.5T met non-inferiority criteria vs. GRAPPA-TOF for overall image quality, reducing scan time by 38.7% while preserving aneurysm measurement reliability. However, reduced CNR and reader-preference variability important trade-offs. These findings support the use of CS-accelerated-TOF as a time-efficient alternative to GRAPPA-accelerated-TOF in evaluating intracranial aneurysms, though further research on field-strength effects and small aneurysms is warranted.

BACKGROUND: 3D-FLAIR is central to MR-based diagnosis and monitoring of MS, but long acquisition times remain a limitation. OBJECTIVES: This single-center prospective non-inferiority study evaluated whether compressed sensing (CS) – accelerated 3D-FLAIR at 1.5T provides lesion detection comparable to optimized Generalized Autocalibrating Partially Parallel Acquisition (GRAPPA) – accelerated 3D-FLAIR. Optimized CS- and GRAPPA-accelerated 3D-FLAIR sequences were incorporated into MRI examinations in patients with known or suspected MS. The primary endpoint was manual lesion count by two blinded readers using a 10% non-inferiority margin. Secondary endpoints included image quality, SNR, CNR, and automated lesion count and volumetry. RESULTS: Sixty-eight patients were included (mean age, 40.1±13.3 years; 61.8% women). CS-accelerated 3D-FLAIR reduced acquisition time by 31.8% compared with GRAPPA (4:00 vs 5:52 minutes). Non-inferiority for manual lesion count was demonstrated for both readers (reader A, p < .0001; reader B, p = .005). Interrater agreement was excellent for CS (ICC = 0.921; 95% CI, 0.837-0.957) and very good for GRAPPA (ICC = 0.851; 95% CI, 0.769-0.906). Subjective image quality was high for both techniques. GRAPPA showed higher objective signal-to-noise-ratio (SNR) and contrast-to-noise-ratio (CNR), whereas automated lesion counts and volumes were higher for CS. CONCLUSION: CS-accelerated 3D-FLAIR provided non-inferior lesion detection with substantial scan-time reduction.

Visualizations are vital for communicating scientific results. Historically, brain images in neuroscience figures have only depicted regions that surpass a given statistical threshold. This practice substantially biases interpretation of the results and subsequent meta-analyses, particularly toward non-reproducibility. We advocate for ‘transparent thresholding’ that not only highlights statistically significant regions but also includes subthreshold locations, retaining key experimental context. This balances the dual needs of distilling modeling results and enabling informed interpretations of neuroimaging results. Transparent thresholding removes ambiguity, decreases hypersensitivity to nonphysiological features, helps catch potential artifacts, improves cross-study comparisons, reduces non-reproducibility biases and clarifies interpretations. We address considerations raised by researchers in the field and highlight the many software packages implementing transparent thresholding, several of which were added or streamlined as part of this work. We hope that by showing how transparent thresholding can meaningfully improve the interpretation (and reproducibility) of neuroimaging findings, we will encourage more researchers to adopt this method.

Background/Objectives: Lead acrylic shields (LASs) enhance radiation protection, with variation of their usage among different specialties. This prospective multicentric observational study aimed to explore patterns of ocular radiation exposure and LAS usage among interventionalists from different disciplines and to assess behavioral dose changes in a longitudinally monitored subgroup. Methods: From July 2019 to July 2020, ocular doses (protected and unprotected) were measured in 15 interventionalists from four specialties (radiology, neuroradiology, cardiology and vascular surgery) across 2286 procedures using thermoluminescent dosimeters. Procedure type, operator position, total body dose, fluoroscopy time, dose area product, LAS usage and dose exceedances were documented. Ocular doses of five interventionalists, who participated in our previous study, allowed a longitudinal comparison of radiation doses and protective behavior. Results: Cumulative annual unprotected ocular doses ranged from 0 to 59 mSv, with five participants exceeding the annual limit of 20 mSv, whereas protected doses (0 to 18 mSv) remained within the limits. Procedural LAS usage was seen in 89% of radiologists and 82% of vascular surgeons. Participants with 100% LAS usage recorded minimal measurable ocular doses, whereas lower LAS compliance resulted in higher ocular doses. Longitudinal subgroup data analyses showed a decrease in ocular dose per procedure in all five participants, suggesting a potential learning effect, without statistical significance. Conclusions: Unprotected ocular doses exceeded the annual occupational eye lens dose limit in several participants, whereas protected doses remained within recommended limits in all participants. No specialty demonstrated universally lower ocular doses, while consistent LAS use proved highly effective in reducing the dose in all groups. Longitudinal findings suggest that structured dose monitoring and repeated training may support behavioral improvements in radiation protection over time.

Purpose: Stentretrievers are key devices for endovascular treatment of acute ischemic stroke. Aim of this post market clinical follow-up study was to asses safety and outcomes of interventions using the APERIO® Hybrid/Hybrid ^17|21 thrombectomy device (AHD) in routine clinical use. Methods: We conducted a prospectively monitored, multicenter, national registry study with single-arm data collection including patients with acute intracranial vessel occlusion (anterior and posterior circulation, including medium vessel occlusions) who were treated with the AHD in Germany between November 2020 and June 2023. Patients ( n = 173) with low pre-stroke morbidity (modified Rankin Scale [mRS] ≤ 2) were included. We assessed technical recanalization success (mTICI ≥ 2b), the occurrence of periprocedural symptomatic intracranial hemorrhages (sICH), good clinical outcome (mRS ≤ 2 at 90 days), and secondary outcomes. Results: Recanalization mTICI ≥ 2b was achieved in 84.4% with the AHD only, including 47.4% first pass success. Good clinical outcome at 90 days (mRS ≤ 2) was observed in 68.8%. Good primary safety outcome (no periprocedural sICH) was observed, notably even despite a high rate (79.8%) of stentretriever oversizing. Conclusion: The AHD is effective and safe. Technical success, primary safety and clinical outcomes surpassed earlier registries on different stentretrievers of the same and earlier generations. However, further studies are warranted to clarify whether these outcomes reflect true advantages of the device, improvements in thrombectomy setups and techniques, or selection biases.

BACKGROUND AND IMPORTANCE: This case highlights the effectiveness of endovascular balloon dilatation (percutaneous transluminal angioplasty (PTA)) for treating vasospasm in a radial artery (RA) bypass graft from the internal carotid artery to the M2 branch of the middle cerebral artery in a patient with severe subarachnoid hemorrhage. CLINICAL PRESENTATION: A 69-year-old woman with severe subarachnoid hemorrhage due to a ruptured giant aneurysm in the ophthalmic segment of the right internal carotid artery underwent an extracranial-intracranial high-flow bypass with a RA graft, followed by trapping of the aneurysm. During her intensive care unit stay, vasospasms developed primarily in the intracranial radial graft and M2 branches. These spasms showed only minimal improvement after standard care and intra-arterial vasospasmolysis with nimodipine. Thus, after systemic anticoagulation, balloon PTA was performed, treating both the intracranial and extracranial sections of the graft, including areas near the anastomosis. The procedure was complication-free, with immediate morphological success and significant improvement in perfusion to the middle cerebral artery territory. CONCLUSION: Endovascular balloon PTA should be considered a rescue measure for vasospasm in extracranial-intracranial bypasses, particularly with RA grafts post-SAH. Owing to its muscular structure, the RA graft is especially prone to spasm, potentially compromising graft patency. When pharmacological treatments fail, balloon PTA offers a targeted intervention to restore vessel caliber, stabilizing blood flow and preventing ischemic complications, thus supporting the bypass's long-term success.

This atlas-based network correspondence analysis assessed how ASPECTS regions routinely assessed in clinical acute stroke imaging are related to functional brain networks. Cortical ASPECTS regions exhibit patterns of predominant overlap with functional brain networks, albeit with limited correspondence of ASPECTS region boundaries and network boundaries. Examples are associations of the left M1 mainly with the language and fronto-parietal cognitive control networks and the M2 regions with an auditory network.

Background and Purpose: Stentretrievers are key devices for endovascular treatment of acute ischemic stroke. Aim of this post market clinical follow-up study was to asses safety and outcomes of interventions using the APERIO® Hybrid/Hybrid ^17|21 thrombectomy device (AHD) in routine clinical use. Materials and Methods: Prospective monitored multicentric national registry of patients with acute intracranial vessel occlusion treated with the AHD in Germany between 11/2020 and 06/2023. Inclusion of patients (n = 173) with low pre-stroke morbidity (mRS <= 2). Assessment of technical recanalization success (mTICI >= 2b), periprocedural symptomatic intracranial hemorrhages (sICH), good clinical outcome (mRS <= 2) at 90 days, and secondary outcomes. Results: Recanalization mTICI ≥ 2b was achieved in 97.1 % of the patients, 84.4 % with the AHD only, including 47.4 % first pass success. Good clinical outcome at 90 days (mRS ≤ 2) was observed in 68.8 %. Good primary safety outcome (no periprocedural sICH) was observed, notably even despite a high rate (79.8 %) of stentretriever oversizing. Conclusions: The AHD is effective and safe. Technical success, primary safety and clinical outcomes surpassed earlier registries on different stentretrievers of the same and earlier generations. However, further studies are warranted to clarify whether these outcomes reflect true advantages of the device, improvements in thrombectomy setups and techniques, or selection biases. Key messages: The most important instruments for endovascular stroke treatment, the stent retrievers, differ significantly in design and knowledge about the effects of these differences is limited. The APERIO® Hybrid/Hybrid ^17|21 thrombectomy device (AHD) is effective and safe. Further studies are warranted to clarify, whether the superior outcomes identified in this registry study reflect true advantages of the AHD.