Roadmap Guided Direct Percutaneous Vertebral Artery Puncture for Mechanical Thrombectomy of Acute Basilar Artery Occlusion: A Technical Case Report and Review of the Literature

Access techniques for mechanical thrombectomy normally include percutaneous puncture of the common femoral or, more recently, the radial artery. Although target vessel catheterization may frequently not be devoid of difficulties via both routes, the vast majority of mechanical thrombectomy (MT) cases can be successfully managed. However, in a significant minority of cases, a stable target vessel access cannot be reached resulting in futile recanalization procedures and detrimental outcomes for the patients. As such, in analogy to direct carotid puncture for anterior circulation MT, direct vertebral artery (VA) puncture (DVP) is a direct cervical approach, which can constitute the only feasible access to the posterior circulation in highly selected cases. So far, due to the rarity of DVP, only anecdotal evidence from isolated case reports is available and this approach raises concerns with regard to safety issues, feasibility, and technical realization. We present a case in which bail-out access to the posterior circulation was successfully obtained through a roadmap-guided lateral direct puncture of the V2 segment of the cervical VA and give an overview of technical nuances of published DVP approaches for posterior circulation MT

Experimental and numerical investigation of edge tones

We study both, by experimental and numerical means the fluid dynamical phenomenon of so-called edge tones. Of particular interest is the clarification of certain scaling laws relating the frequency ƒ to geometrical quantities, namely 푑, the height of the jet, 푤, the stand-off distance and the velocity of the jet. We conclude that the Strouhal number S푑 is given by S푑 = C · (푑/푤)푛 with 푛 ≈ 1 in our case. Moreover, the constant C of the experiment agrees within 10-15% with the result of the simulation. As for the frequency dependence on the geometry and on the jet velocity there is a very good agreement of experimental and numerical results

A Case-Control Study

Purpose: To evaluate diffusion abnormalities of the retina and optic nerve in patients with central retinal artery occlusion (CRAO) using standard stroke diffusion-weighted magnetic resonance imaging (DWI). Methods: In this case-control study, DWI scans of patients with nonarteritic CRAO were retrospectively assessed for acute ischemia of the retina and optic nerve. Two neuroradiologists, blinded for patient diagnosis, randomly evaluated DWI of CRAO patients and controls (a collective of stroke and transient ischemic attack [TIA] patients) for restrictions of the retina and optic nerve. We calculated statistical quality criteria and analyzed inter-rater reliability using unweighted Kappa statistics. Results: 20 CRAO patients (60,6 ± 17 years) and 20 controls (60,7 ± 17 years) were included in the study. Sensitivity, specificity, positive and negative predictive values for retinal DWI restrictions were 75%/80%/79%/76% (reader 1) and 75%/100%/100%/80% (reader 2), respectively. Unweighted Kappa was κ = 0,70 (95% CI 0,48‑0,92), indicating "substantial" interrater reliability. In comparison, sensitivity, specificity, PPV and NPV (positive and negative predictive values) for restrictions of the optic nerve in CRAO were 55%/70%/65%/61% (reader 1) and 25%/100%/100%/57% (reader 2). Inter-rater reliability was "fair" with unweighted Kappa κ = 0,32 (95% CI 0,09‑0,56). Conclusions: Retinal diffusion restrictions were present in a majority of CRAO patients and detectable with reasonable sensitivity, high specificity and substantial inter-rater reliability. Further studies are necessary to study time dependency of retinal diffusion restrictions, improve image quality and investigate the reliability of retinal DWI to discern CRAO from other causes of acute loss of vision

Determination of Bulk Magnetic Volume Properties by Neutron Dark-Field Imaging

For the production of high-class electrical steel grades a deeper understanding of the magnetic domain interaction with induced mechanical stresses is strongly required. This holds for non-oriented (NO) as well as grain-oriented (GO) steels. In the case of non-oriented steels the magnetic property degeneration after punching or laser cutting is essential for selecting correct obstructing material grades and designing efficient electrical machines. Until now these effects stay undiscovered due to the lack of adequate investigation methods that reveal local bulk information on processed laminations. Here we show how the use of a non-destructive testing method based on a neutron grating interferometry providing the dark-field image contrast delivers spatially-resolved transmission information about the local bulk domain arrangement and domain wall density. With the help of this technique it is possible to visualize magnetization processes within the NO laminations. Different representative manufacturing techniques are compared in terms of magnetic flux density deterioration such as punching, mechanically cutting by guillotine as well as laser fusion cutting using industrial high power laser beam sources. For GO steel laminations the method is applicable on the one hand to visualize the internal domain structure without being hindered by the coating layer. On the other hand, we can show the influence of the coating layer onto the underlying domain structure

Determination of Bulk Magnetic Volume Properties by Neutron Dark-Field Imaging

For the production of high-class electrical steel grades a deeper understanding of the magnetic domain interaction with induced mechanical stresses is strongly required. This holds for non-oriented (NO) as well as grain-oriented (GO) steels. In the case of non-oriented steels the magnetic property degeneration after punching or laser cutting is essential for selecting correct obstructing material grades and designing efficient electrical machines. Until now these effects stay undiscovered due to the lack of adequate investigation methods that reveal local bulk information on processed laminations. Here we show how the use of a non-destructive testing method based on a neutron grating interferometry providing the dark-field image contrast delivers spatially-resolved transmission information about the local bulk domain arrangement and domain wall density. With the help of this technique it is possible to visualize magnetization processes within the NO laminations. Different representative manufacturing techniques are compared in terms of magnetic flux density deterioration such as punching, mechanically cutting by guillotine as well as laser fusion cutting using industrial high power laser beam sources. For GO steel laminations the method is applicable on the one hand to visualize the internal domain structure without being hindered by the coating layer. On the other hand, we can show the influence of the coating layer onto the underlying domain structure

Quantitative biparametric analysis of hybrid 18F-FET PET/MR-neuroimaging for differentiation between treatment response and recurrent glioma

We investigated the diagnostic potential of simultaneous 18F-FET PET/MR-imaging for differentiation between recurrent glioma and post-treatment related effects (PTRE) using quantitative volumetric (3D-VOI) lesion analysis. In this retrospective study, a total of 42 patients including 32 patients with histologically proven glioma relapse and 10 patients with PTRE (histopathologic follow-up, n = 4, serial imaging follow-up, n = 6) were evaluated regarding recurrence. PET/MR-imaging was semi-automatically analysed based on FET tracer uptake using conservative SUV thresholding (isocontour 80%) with emphasis on the metabolically most active regions. Mean (relative) apparent diffusion coefficient (ADCmean, rADCmean), standardised-uptake-value (SUV) including target-to-background (TBR) ratio were determined. Glioma relapse presented higher ADCmean (MD ± SE, 284 ± 91, p = 0.003) and TBRmax (MD ± SE, 1.10 ± 0.45, p = 0.02) values than treatment-related changes. Both ADCmean (AUC ± SE = 0.82 ± 0.07, p-value < 0.001) and TBRmax (AUC ± SE = 0.81 ± 0.08, p-value < 0.001) achieved reliable diagnostic performance in differentiating glioma recurrence from PTRE. Bivariate analysis based on a combination of ADCmean and TBRmax demonstrated highest diagnostic accuracy (AUC ± SE = 0.90 ± 0.05, p-value < 0.001), improving clinical (false negative and false positive) classification. In conclusion, biparametric analysis using DWI and FET PET, both providing distinct information regarding the underlying pathophysiology, presented best diagnostic accuracy and clinical benefit in differentiating recurrent glioma from treatment-related changes

Retinal diffusion restrictions in acute branch retinal arteriolar occlusion

This study sought to investigate the occurrence of retinal diffusion restrictions (RDR) in branch retinal arteriolar occlusion (BRAO) using standard brain diffusion-weighted imaging (DWI). Two radiologists assessed DWI MRI scans of BRAO patients for RDR in a retrospective cohort study. Inter- and intrarater reliability were calculated using Kappa statistics. Detection rates of RDR were compared among MRI scans with varying field strength, sequence type and onset-to-DWI time intervals. 85 BRAO patients (63.1 +/- 16.5 years) and 89 DWI scans were evaluated. Overall sensitivity of RDR in BRAO was 46.1% with visually correlating low ADC signal in 56.1% of cases. Localization of RDR matched distribution of fundoscopic retinal edema in 85% of patients. Inter- and intra-rater agreement for RDR in BRAO was kappa(inter) = 0.64 (95% CI 0.48-0.80) and kappa(intra) = 0.87 (95% CI 0.76-0.96), respectively. RDR detection rate tended to be higher for 3T, when compared to 1.5T MRI scans (53.7% vs. 34.3%%; p = 0.07). RDR were identified within 24 h up to 2 weeks after onset of visual impairment. RDR in BRAO can be observed by means of standard stroke DWI in a substantial proportion of cases, although sensitivity and interrater reliability were lower than previously reported for complete central retinal artery occlusion

Author Correction: Quantitative biparametric analysis of hybrid 18F-FET PET/MR-neuroimaging for differentiation between treatment response and recurrent glioma

An amendment to this paper has been published and can be accessed via a link at the top of the paper

Direct puncture of the carotid artery as a bailout vascular access technique for mechanical thrombectomy in acute ischemic stroke—the revival of an old technique in a modern setting

Purpose: To describe our single-center experience of mechanical thrombectomy (MTE) via a direct carotid puncture (DCP) with regard to indication, time metrics, procedural details, as well as safety and efficacy aspects. Methods: DCP thrombectomy cases performed at our center were retrospectively identified from a prospectively maintained institutional MTE database. Various patient (age, sex, stroke cause, comorbidities), clinical (NIHSS, mRS), imaging (occlusion site, ASPECT score), procedural (indication for DCP, time from DCP to reperfusion, materials used, technical nuances), and outcome data (NIHSS, mRS) were tabulated. Results: Among 715 anterior circulation MTEs, 12 DCP-MTEs were identified and analyzed. Nine were left-sided M1 occlusions, one right-sided M1 occlusion, and two right-sided M2 occlusions. DCP was successfully carried out in 91.7%; TICI 2b/3-recanalization was achieved in 83.3% via direct lesional aspiration and/or stent-retrieval techniques. Median time from DCP to reperfusion was 23 min. Indications included futile transfemoral catheterization attempts of the cervical target vessels as well as iliac occlusive disease. Neck hematoma occurred in 2 patients, none of which required further therapy. Conclusion: MTE via DCP in these highly selected patients was reasonably safe, fast, and efficient. It thus represents a valuable technical extension of MTE, especially in patients with difficult access