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Intracranial aneurysms (IA) is not-uncommon pathology of cerebral vessels. Vessel wall magnetic resonance imaging can visualize the vascular walls of IAs. In some aneurysms, the wall-adjacent and a luminal hyperintense signal was detected. The signal was attributed to the inflammation and specific hemodynamic features of aneurysms. But, up to now, the studies investigating luminal enhancement combined with flow analysis are limited. Therefore, in this study, investigation of the luminal enhancement is further carried out by comparison to computational fluid dynamics. The latter provides the possibility of calculating hemodynamic parameters, which can give information such as velocity, pressure, and shear stress fields throughout a heart cycle. The data of the IAs is specific to each patient and builds the basis for the enhancement analysis and simulations. Specific hemodynamic parameters like kinetic energy and vortex formation evaluated in the simulations show a dependency to signal suppression recorded with vessel wall magnetic resonance imaging

Purpose Intracranial aneurysm (IA) wall enhancement on post-contrast vessel wall magnetic resonance imaging (VW-MRI) is assumed to be a biomarker for vessel wall inflammation and aneurysm instability. However, the exact factors contributing to enhancement are not yet clarified. This study investigates the relationship between luminal enhancement and intra-aneurysmal flow behaviour to assess the suitability of VW-MRI as a surrogate method for determining quantitative and qualitative flow behaviour in the aneurysm sac. Methods VW-MRI signal is measured in the lumen of three patient-specific IA flow models and compared with the intra-aneurysmal flow fields obtained using phase-contrast magnetic resonance imaging (PC-MRI) and computational fluid dynamics (CFD). The IA flow models were supplied with two different time-varying flow regimes. Results Overall, the velocity fields acquired using PC-MRI or CFD were in good agreement with the VW-MRI enhancement patterns. Generally, the regions with slow-flowing blood show higher VW-MRI signal intensities, whereas high flow leads to a suppression of the signal. For all aneurysm models, a signal value above three was associated with velocity values below three cm/s. Conclusion Regions with lower enhancements have been correlated with the slow and high flow at the same time. Thus, further factors like flow complexity and stability can contribute to flow suppression in addition to the flow magnitude. Nevertheless, VW-MRI can qualitatively assess intra-aneurysmal flow phenomena and estimate the velocity range present in the corresponding region.

To investigate the diagnostic value of dual-layer spectral detector computed tomography (SDCT) in detecting posttraumatic prevertebral hematoma of the cervical spine by including electron density images. 38 patients with post-traumatic imaging of the cervical spine were included in this study and received both SDCT and MRI examinations. MRI was set as the reference and combined conventional/electron density (C + ED) images were compared to conventional CT (CCT) images alone. A total of 18 prevertebral hematomas were identified. Reader 1 identified 14 of 18 and reader 2 15 of 18 prevertebral hematomas by using C + ED reconstructions. Readers 1 and 2 detected 6 and 9 of 18 hematomas on CCT, respectively. CCT showed a sensitivity of 33-50 % and a specificity of 75-80 %, while for C + ED reconstructed images the sensitivity was 77-83 % and the specificity was 85-90 %. Accuracy increased from 55-66 % to 84 % by using C + ED images. The minimum thickness for detecting hematoma on C + ED images was 3 mm. The sizes of prevertebral hematoma on CCT/C + ED were not significantly under- or overestimated compared to the MRI reference. There was a significant difference between the two readers for measuring hematoma sizes on CCT (p = 0.04). Readers showed an excellent inter-rater reliability (kappa = 0.82) for C + ED images and a moderative inter-rater reliability (kappa = 0.44) for CCT. With SDCT, the diagnostic accuracy for detecting post-traumatic prevertebral hematoma is improved by using combined conventional and electron density reconstructions compared to conventional images alone. · SDCT has a high potential for detecting post-traumatic prevertebral hematomas of the cervical spine by using combined conventional and electron density images.. · Prevertebral hematomas with a thickness of less than 3 mm cannot be reliably identified by SDCT.. · There is no discernible value of conventional SDCT images for diagnosing prevertebral hematoma..· Sedaghat S, Langguth P, Larsen N et al. Diagnostic Accuracy of Dual-Layer Spectral CT Using Electron Density Images to Detect Post-Traumatic Prevertebral Hematoma of the Cervical Spine. Fortschr Röntgenstr 2021; 193: 1445 - 1450. Untersuchung der diagnostischen Wertigkeit der Dual-Layer-Spektraldetektor-Computertomografie (SDCT) zur Erkennung von posttraumatischen prävertebralen Hämatomen der Halswirbelsäule unter Verwendung von Elektronendichtebildern. 38 Patienten mit posttraumatischer Bildgebung der Halswirbelsäule wurden in diese Studie eingeschlossen und erhielten sowohl SDCT- als auch MRT-Untersuchungen. Die MRT wurde als Referenz festgelegt. Kombinierte konventionelle und Elektronendichtebilder (C + ED) wurden mit konventionellen Bildern (CCT) verglichen. Insgesamt wurden 18 prävertebrale Hämatome identifiziert. Reader 1 identifizierte 14 von 18 und Reader 2 15 von 18 prävertebrale Hämatome unter Verwendung von C + ED-Bildern. Reader 1 und 2 entdeckten 6 bzw. 9 von 18 Hämatomen mittels CCT. Bei CCT-Bildern zeigte sich eine Sensitivität von 33–50 % und eine Spezifität von 75–80 %, während für C + ED-Bilder eine Sensitivität von 77–83 % und eine Spezifität von 85–90 % ermittelt wurde. Die Genauigkeit wurde unter Verwendung von C + ED-Bildern von 55–66 % auf 84 % erhöht. Die Mindestdicke zum Nachweis von Hämatomen auf C + ED-Bildern betrug 3 mm. Das Ausmaß der prävertebralen Hämatome wurde weder bei CCT- noch bei C + ED-Bildern im Vergleich zur MRT-Referenz signifikant unter- oder überschätzt. Dagegen gab es einen signifikanten Unterschied zwischen den beiden Readern in Bezug auf die Messung der Hämatomgrößen in CCT-Bildern (p = 0,04). Die Reader zeigten eine exzellente Interrater-Übereinstimmung (kappa = 0,82) für C + ED-Bilder und eine moderate Interrater-Übereinstimmung (kappa = 0,44) für CCT-Bilder. Durch die Verwendung von kombinierten konventionellen und Elektronendichtebildern lässt sich bei der SDCT die diagnostische Genauigkeit zur Erkennung von posttraumatischen prävertebralen Hämatomen im Vergleich zu konventionellen Bildern steigern. · SDCT hat ein hohes Potenzial zur Erkennung von posttraumatischen prävertebralen Hämatomen der Halswirbelsäule unter Verwendung von kombinierten konventionellen und Elektronendichtebildern.. · Prävertebrale Hämatome mit einer Dicke von weniger als 3 mm können durch die SDCT nicht sicher identifiziert werden.. · Konventionelle SDCT-Bilder sind für die Diagnose eines prävertebralen Hämatoms ungeeignet..

BACKGROUND Vessel-wall enhancement (VWE) on black-blood MRI (BB MRI) has been proposed as an imaging marker for a higher risk of rupture and associated with wall inflammation. Whether VWE is causally linked to inflammation or rather induced by flow phenomena has been a subject of debate. PURPOSE To study the effects of slow flow, spatial resolution, and motion-sensitized driven equilibrium (MSDE) preparation on signal intensities in BB MRI of patient-specific aneurysm flow models. STUDY TYPE Prospective. SUBJECTS/FLOW ANEURYSM MODEL/VIRTUAL VESSELS Aneurysm flow models based on 3D rotational angiography datasets of three patients with intracranial aneurysms were 3D printed and perfused at two different flow rates, with and without Gd-containing contrast agent. FIELD STRENGTH/SEQUENCE Variable refocusing flip angle 3D fast-spin echo sequence at 3 T with and without MSDE with three voxel sizes ((0.5 mm)3 , (0.7 mm)3 , and (0.9 mm)3 ); time-resolved with phase-contrast velocity-encoding 3D spoiled gradient echo sequence (4D flow MRI). ASSESSMENT Three independent observers performed a qualitative visual assessment of flow patterns and signal enhancement. Quantitative analysis included voxel-wise evaluation of signal intensities and magnitude velocity distributions in the aneurysm. STATISTICAL TESTS Kruskal-Wallis test, potential regressions. RESULTS A hyperintense signal in the lumen and adjacent to the aneurysm walls on BB MRI was colocalized with slow flow. Signal intensities increased by a factor of 2.56 ± 0.68 (P

Purpose Recurrent stroke is considered to increase the incidence of severe disability and death. For correct risk assessment and patient management it is essential to identify the origin of stroke at an early stage. Transthoracic echocardiography (TTE) is the initial standard of care for evaluating patients in whom a cardioembolic source of stroke (CES) is suspected but its diagnostic capability is limited. Transesophageal echocardiography (TEE) is considered as gold standard; however, this approach is time consuming, semi-invasive and not always feasible. We hypothesized that adding a delayed-phase cardiac computed tomography (cCT) to initial multimodal CT might represent a valid alternative to routine clinical echocardiographic work-up. Material and Methods Patients with suspected acute cardioembolic stroke verified by initial multimodal CT and subsequently examined with cCT were included. The cCT was evaluated for presence of major CES and compared to routine clinical echocardiographic work-up. Results In all, 102 patients with suspected acute CES underwent cCT. Among them 60 patients underwent routine work-up with echocardiography (50 TTE and only 10 TEE). By cCT 10/60 (16.7%) major CES were detected but only 4 (6.7%) were identified by echocardiography. All CES observed by echocardiography were also detected by cCT. In 8 of 36 patients in whom echocardiography was not performed cCT also revealed a major CES. Conclusion These preliminary results show the potential diagnostic yield of delayed-phase cCT to detect major CES and therefore could accelerate decision-making to prevent recurrence stroke. To confirm these results larger studies with TEE as the reference standard and also compared to TTE would be necessary.

Purpose Circumferential enhancement on MR vessel wall imaging has been proposed as a biomarker of a higher risk of rupture in intracranial aneurysms. Focal enhancement is frequently encountered in unruptured aneurysms, but its implication for risk stratification and patient management remains unclear. This study investigates the association of focal wall enhancement with hemodynamic and morphological risk factors and histologic markers of wall inflammation and degeneration. Methods Patients with an unruptured middle cerebral artery aneurysm who underwent 3D rotational angiography and 3T MR vessel wall imaging showing focal wall enhancement were included. Hemodynamic parameters were calculated based on flow simulations and compared between enhanced regions and the entire aneurysm surface. Morphological parameters were semiautomatically extracted and quantitatively associated with wall enhancement. Histological analysis included detection of vasa vasorum, CD34, and myeloperoxidase staining in a subset of patients. Results Twenty-two aneurysms were analyzed. Enhanced regions were significantly associated with lower AWSS, lower maxOSI, and increased LSA. In multivariate analysis, higher ellipticity index was an independent predictor of wall enhancement. Histologic signs of inflammation and degeneration and higher PHASES score were significantly associated with focal enhancement. Conclusion Focal wall enhancement is colocalized with hemodynamic factors that have been related to a higher rupture risk. It is correlated with morphological factors linked to rupture risk, higher PHASES score, and histologic markers of wall destabilization. The results support the hypothesis that focal enhancement could serve as a surrogate marker for aneurysm instability.

Background The key imaging features of cerebral amyloid angiopathy (CAA) are lobar, cortical, or cortico-subcortical microbleeds, macrohaemorrhages and cortical superficial siderosis (cSS). In contrast, hypertensive angiopathy is characterized by (micro) haemorrhages in the basal ganglia, thalami, periventricular white matter or the brain stem. Another distinct form of haemorrhagic microangiopathy is mixed cerebral microbleeds (mixed CMB) with features of both CAA and hypertensive angiopathy. The distinction between the two entities (CAA and mixed CMB) is clinically relevant because the risk of haemorrhage and stroke should be well balanced if oral anticoagulation is indicated in CAA patients. We aimed to comprehensively compare these two entities. Methods Patients with probable CAA according to the modified Boston criteria and mixed CMB without macrohaemorrhage were retrospectively identified from our database. Comprehensive comparison regarding clinical and radiological parameters was performed between the two cohorts. Results Patients with CAA were older (78 ± 8 vs. 74 ± 9 years, p = 0.036) and had a higher prevalence of cSS (19% vs. 4%, p = 0.027) but a lower prevalence of lacunes (73% vs. 50%, p = 0.018) and deep lacunes (23% vs. 51%, p = 0.0003) compared to patients with mixed CMB. Logistic regression revealed an association between the presence of deep lacunes and mixed CMB. The other collected parameters did not reveal a significant difference between the two groups. Conclusions CAA and mixed CMB demonstrate radiological differences in the absence of macrohaemorrhages. However, more clinically available biomarkers are needed to elucidate the contribution of CAA and hypertensive angiopathy in mixed CMB patients.

Background Recently, a novel intrasaccular device (contour neurovascular system, contour) was introduced to treat intracranial aneurysms. Contour is placed at thе aneurysm neck and reduces the intraaneurysmal blood inflow. Contour comes in a range of sizes to target different aneurysms. The efficiency of altering flow with contour and the effect of device size have not yet been investigated. Therefore, we studied the effect of the device size with patient-based aneurysm models using 2D digital subtraction angiography (DSA). Methods Three patient-based aneurysm models with necks ranging from 2.7 to 9.7 mm were produced, providing standardized testing conditions. Contours with diameters of 5, 11, and 14 mm were implanted into the models, four of each size. 2D DSA images were acquired before and after implanting contour (15 frames/s, manual contrast injection). After injecting angiographic contrast agent, the DSA signal was recorded over time to calculate the contrast washout time (WOT), which is a measure of flow diversion efficiency. Results All contour devices caused contrast agent stasis and increased WOT in aneurysm sac ( p-value = 0.0005). The median relative WOT was largest for 5-mm contour (6.6 ± 3.2) and similar for 11-mm contour (3.4 ± 2.6) and 14-mm contour (3.2 ± 3.8). The implantation procedure might affect WOT values even for contours of the same size; the overall relative WOT ranged between 1.5 and 10.89. Conclusion The 5-mm contour showed the longest WOT value in our study, while no apparent difference between 11-mm contour and 14-mm contour was found.

Wall enhancement of intracranial aneurysms in vessel wall magnetic resonance imaging (MRI) has been linked to aneurysm progression. The clinical significance of aneurysm enhancement after embolization has not yet been investigated. The goal of this study was to identify factors associated with aneurysm wall enhancement and reperfusion after embolization. Patients who underwent treatment of intracranial aneurysms with coils or the Woven Endobridge (WEB) and follow-up MR vessel wall imaging were included. Enhancement of the treated aneurysms was separately recorded for the following locations: a) wall at the neck, b) wall at the dome, and c) in the aneurysmal cavity. Reperfusion was determined on follow-up digital subtraction angiography (DSA) and MR time of flight (TOF) angiography. In this study 48 patients with 53 aneurysms were included. Wall enhancement at the neck and the dome of the aneurysm was significantly associated with time between embolization and follow-up MRI under 6 months. Enhancement inside the aneurysmal cavity was significantly associated with a follow-up time longer than 6 months, and with stable aneurysms without reperfusion. Wall enhancement is a regular feature in intracranial aneurysms after embolization and decreases over time. Enhancement inside the aneurysmal cavity is associated with a stable state and could possibly serve as an imaging marker of completed aneurysm healing.

A first-pass, direct aspiration technique and stent retrieval with a balloon guide catheter represent advanced thrombectomy techniques that are increasingly being used in the clinical routine. The purpose of this experimental study was to evaluate whether the techniques' effectiveness depended on the clot composition and to visualize the interaction between the devices and the clot. Erythrocyte-rich (red) and fibrin-rich (white) clots were placed into the M1-segment of the middle cerebral artery in a transparent vascular phantom with physiological architecture. Physiological hemodynamic conditions were maintained with a programmable pump. On the one hand direct aspiration with a 5F aspiration catheter (ADAPT) and on the other hand stent retrieval with a balloon guide catheter (flow arrest/reversal) was performed. The experiments were made under direct visual control to observe the interaction between the devices and the clot. The primary end points were the number of passes/maneuvers and the occurrence of distal emboli and emboli in a new territory (anterior cerebral artery), until full recanalization was achieved. The experiment was filmed with a full high-definition camera identifying emboli. Six experiments were conducted for each technique and clot model. Red clots were retrieved by ADAPT with fewer passes and distal emboli, and could usually be aspirated directly at the occlusion site. White clots clogged the tip of the 5F aspiration catheter in every experiment. The catheter had to be pulled back into the long sheath in the cervical internal carotid artery, producing distal emboli. White clots were retrieved by the stent retriever and balloon guide catheter with fewer distal emboli. There was no difference in the number of passes. The stent-thrombus interaction was superficial in both clot models. Successful retrieval was granted by the flow arrest and proximal aspiration/flow reversal. One embolus in a new territory developed when using each technique in white clots. This experimental study showed that the efficacy of advanced thrombectomy techniques might depend on clot composition. Identifying the right technique for the right clot might improve the results of thrombectomy. In a clinical setting the thrombus morphology in non-enhanced CT could be used as a marker for patient selection. · The efficacy of thrombectomy seems to depend on thrombus composition.. · ADAPT might be more effective for rbc-rich clots.. · Thrombectomy with BGC might be more effective for fibrin-rich clots..· Madjidyar J, Pineda Vidal L, Larsen N et al. Influence of Thrombus Composition on Thrombectomy: ADAPT vs. Balloon Guide Catheter and Stent Retriever in a Flow Model. Fortschr Röntgenstr 2020; 192: 257 - 263. Alleinige direkte Aspiration und Stent-Retriever mit Ballon-Führungskathetern stellen erweiterte Thrombektomie-Techniken dar, die ihren festen Bestand in der klinischen Routine haben. In dieser experimentellen Studie sollte untersucht werden, ob die Effektivität dieser Techniken von der Thrombus-Komposition abhängig ist und wie die Interaktion der Thromben mit den einzelnen Devices ist. Erythrozyten-reiche (rot) Thromben und Fibrinthromben (weiß) aus humanem Blut sind in das M1-Segment der A. cerebri media eines transparenten Silikonmodels des vorderen Kreislaufs mit physiologischer Architektur platziert worden. Mittels einer programmierbaren Pumpe wurden physiologische hämodynamische Bedingungen erreicht. Die Thrombektomie erfolgte entweder durch direkte, alleinige Aspiration mittels einem 5F-Aspirationskatheter oder mit einem Stent-Retriever und Ballon-Führungskatheter (Flussarrest/-umkehr). Die Experimente wurden unter Sicht durchgeführt, um die Interaktion zwischen den Thromben und den Devices nachvollziehen zu können. Primäre Endpunkte waren die Anzahl benötigter Thrombektomie-Manöver und das Auftreten von distalen Embolien oder Embolien in neuen Territorien (A. cerebri anterior) bis zur vollständigen Rekanalisation. Die Experimente wurden mit einer Full-HD-Kamera dokumentiert, anhand der Videos wurde das Auftreten von Embolien beurteilt. Pro Thrombus-Art und Thrombektomie-Technik sind jeweils 6 Versuche durchgeführt worden. Rote Thromben konnten mittels alleiniger Aspiration vor Ort geborgen werden, wobei weniger Manöver nötig waren und weniger distale Embolien entstanden. Die weißen Thromben haben die Spitze des Aspirationskatheters in allen Fällen vollständig verstopft, sodass die Thromben ungeschützt bis in die lange Schleuse in der zervikalen A. carotis interna zurückgezogen werden mussten. Weiße Thromben konnten mittels Stent-Retriever und Ballon-Führungskatheter mit distalen Embolien geborgen werden; die Anzahl der Manöver war gleich. Bei beiden Thrombus-Arten war die Interaktion zwischen Stent-Retriever und Thrombus oberflächlich, sodass die Thromben entlang des Stents nach distal rollten. Die erfolgreiche Thrombektomie war vor allem durch den Flussarrest und die Flussumkehr möglich. Embolien in die A.cerebri anterior sind jeweils in 1 Fall mit beiden Techniken bei weißen Thromben aufgetreten. Diese experimentelle Studie zeigt, dass die Effektivität der Thrombektomie-Technik von der Thrombus-Komposition abhängen könnte. Die Identifizierung der richtigen Technik für einen bestimmten Thrombus könnte die Rekanalisationsergebnisse optimieren. Im klinischen Kontext könnte die Morphologie des Thrombus in der dünnschichtigen nativen CT einen Marker für die Auswahl der Technik darstellen. · Die Effektivität der Thrombektomie-Technik scheint von der Thrombus-Komposition abzuhängen.. · Die alleinige Aspiration scheint effektiver für rote Thromben zu sein.. · Stent-Retriever und Ballon-Führungskatheter scheinen effektiver für weiße Thromben zu sein..

A direct aspiration first pass technique (ADAPT) is an effective thrombectomy option in patients with acute ischemic stroke. Balloon guide catheters (BGC) seem to improve the efficacy of stent retrievers and ADAPT. The last generation 6F aspiration catheters require 9F BGCs, which are rigid devices that are challenging to position in a tortuous anatomy. In this experimental study the efficacy of 6F ADAPT alone and 5F ADAPT combined with 8F BGC was evaluated. Either a fibrin rich (white) clot or an RBC rich (red) clot was placed in the M1 segment of a transparent silicon phantom. Physiological hemodynamic conditions were maintained. The clots were retrieved by 6F aspiration catheter via 8F long sheath or 5F aspiration catheter via a flexible 8F BGC. Thrombectomy was performed under direct visual control. The primary endpoints were the number of passes and the number of distal emboli. Ten experiments were made with each clot model and thrombectomy technique (n = 40). Full recanalization could be achieved in every experiment. First pass mTICI 3 could be achieved by 6F ADAPT in 80 % of red clots and 90 % of white clots. Distal emboli were caused in 10 % and 20 %, respectively. When using 5F ADAPT combined with BGC, a first pass mTICI 3 rate of 90 % in red clots and 100 % in white clots could be achieved. A 10 % rate of distal emboli occurred in both groups. In almost all experiments (both techniques), the thrombi clogged the aspiration catheter. No statistically significant differences could be found between the techniques and clot models. 6F ADAPT without BGC was as effective as 5F ADAPT combined with a flexible 8F BGC, with both techniques showing high first-pass recanalization rates and low distal emboli rates. Especially in the case of a tortuous anatomy, these setups should be considered as alternatives to a rigid 9F BGC. The thrombus compositions seemed to be irrelevant in this setting. · 6F ADAPT with no BGC and 5F ADAPT with BGC were very effective and performed equally.. · Both techniques should be considered in tortuous anatomy.. · In this setting the clot composition showed no effect on the recanalization rate..· Madjidyar J, Nerkada L, Larsen N et al. Choosing an Effective and Safe Direct Aspiration Setup for Tortuous Anatomy in Acute Ischemic Stroke: In vitro Study in a Physiological Flow Model. Fortschr Röntgenstr 2021; 193: 544 - 550.ZIEL: Die direkte Kontaktaspiration (ADAPT) ist eine effektive Thrombektomieoption bei Patienten mit akutem ischämischem Schlaganfall. Ballon-Führungskatheter (BGC) scheinen die Effektivität von Stent-Retrievern und ADAPT zu verbessern. Die letzte Generation der 6F-Aspirationskatheter passt nur durch 9F-BGC. Diese sind rigide und in elongierter Anatomie schwierig zu positionieren. In dieser experimentellen Studie wurde die Effektivität von 6F-ADAPT ohne BGC mit der von 5F-ADAPT mit einem flexiblen 8F-BGC verglichen. Ein fibrinreicher (weißer) oder ein Erythrozyten-reicher (roter) Thrombus wurde in das M1-Segment eines transparenten Silikonphantoms mit physiologischer Architektur platziert. Physiologische hämodynamische Bedingungen sind eingestellt worden. Die Thrombektomie wurde mit einem 6F-Aspirationskatheter über eine lange 8F-Schleuse oder mit einem 5F-Aspirationskatheter über einen flexiblen 8F-BGC unter direkter visueller Kontrolle durchgeführt. Primäre Endpunkte waren die Anzahl von Rekanalisationsmanövern und die Anzahl distaler Embolien. Es sind 10 Experimente pro Thrombusart und Thrombektomietechnik durchgeführt worden (n = 40). mTICI 3 nach einem Manöver mittels 6F-ADAPT wurde zu 80 % in roten Thromben und 90 % in weißen Thromben erreicht; es traten distale Embolien in 10 % bzw. 20 % der Fälle auf. Mittels 5F-ADAPT kombiniert mit BGC wurde mTICI 3 nach einem Manöver zu 90 % in roten Thromben und 100 % in weißen Thromben erreicht; es traten distale Embolien in jeweils 10 % der Fälle auf. In fast allen Experimenten (beide Techniken) verstopften die Thromben den Aspirationskatheter. Es konnten keine statistisch signifikanten Unterschiede abhängig von der Thrombuskomposition oder der Thrombektomietechnik festgestellt werden. 6F-ADAPT ohne BGC war genauso effektiv wie 5F-ADAPT kombiniert mit BGC, jeweils mit hohen Rekanalisationsraten nach einem Manöver und geringer Rate an distalen Embolien. Insbesondere bei schwieriger Anatomie sollten diese Techniken als Alternative zu einem rigiden 9F-BGC in Betracht gezogen werden. Die Thrombuskomposition schien nicht relevant zu sein. · 6F-ADAPT ohne BGC und 5F-ADAPT mit BGC waren sehr effektiv und gleichwertig.. · Beide Techniken sollten für schwierige Gefäßanatomien erwogen werden.. · Die Thrombuskomposition zeigte in diesem Aufbau keinen Effekt auf die Rekanalisationsrate..

BACKGROUND AND PURPOSE: Recent studies have suggested that wall enhancement of unruptured intracranial aneurysms in high-resolution MR imaging might serve as an imaging biomarker for higher risk of rupture. Histologic studies have revealed a possible association among inflammatory processes, degeneration, and destabilization of the aneurysm wall preceding rupture. Understanding the histologic condition underlying aneurysm wall enhancement could be an important step toward assessing the value of this method for risk stratification. We present our observations of aneurysm wall enhancement in MR vessel wall imaging and underlying histologic changes. MATERIALS AND METHODS: We reviewed records of patients with an unruptured middle cerebral artery aneurysm who underwent MR vessel wall imaging before aneurysm clipping. Contrast enhancement of the aneurysm wall was dichotomized into either none/faint or strong. Histologic analysis included myeloperoxidase stain for detection of inflammatory cell invasion and CD34 stain for assessment of neovascularization and vasa vasorum. RESULTS: Thirteen aneurysms were included. Five aneurysms showed strong wall enhancement. Among these, myeloperoxidase staining revealed inflammatory cell infiltration in 4. Three showed neovascularization. In 2 aneurysms, vasa vasorum were present. Seven aneurysms did not show wall enhancement; 1 had only mild enhancement. None of these bore evidence of inflammatory cell invasion or neovascularization, and they all lacked vasa vasorum. CONCLUSIONS: Wall enhancement in MR vessel wall imaging is associated with inflammatory cell invasion, neovascularization, and the presence of vasa vasorum. Enhancement does not occur when histologic signs of inflammation are absent. Our results support the hypothesis that MR vessel wall imaging could provide valuable information for risk stratification.

BACKGROUND AND PURPOSE: Non-contrast-enhanced MRA techniques have experienced a renaissance due to the known correlation between the use of gadolinium-based contrast agents and the development of nephrogenic systemic fibrosis and the deposition of gadolinium in some brain regions. The purpose of this study was to assess the diagnostic performance of ungated non-contrast-enhanced radial quiescent-interval slice-selective MRA of the extracranial supra-aortic arteries in comparison with conventional contrast-enhanced MRA in patients with clinical suspicion of carotid stenosis. MATERIALS AND METHODS: In this prospective study, both MRA pulse sequences were performed in 31 consecutive patients (median age, 68.8 years; 19 men). For the evaluation, the cervical arterial system was divided into 35 segments (right and left side). Three blinded reviewers separately evaluated these segments. An ordinal scoring system was used to assess the image quality of arterial segments and the stenosis grading of carotid arteries. RESULTS: Overall venous contamination in quiescent-interval slice-selective MRA was rated as “none” by all readers in 84.9% of cases and in 8.1% of cases in contrast-enhanced MRA (P < .0001). The visualization quality of arterial segments was considered good to excellent in 40.2% for the quiescent-interval slice-selective MRA and in 52.2% for the contrast-enhanced MRA (P < .0001). The diagnostic accuracy of ungated quiescent-interval slice-selective MRA concerning the stenosis grading showed a total sensitivity and specificity of 85.7% and 90.0%, respectively. CONCLUSIONS: Ungated quiescent-interval slice-selective MRA can be used clinically as an alternative to contrast-enhanced MRA without a significantly different image quality or diagnostic accuracy for the detection of carotid stenosis at 1.5T.

Purpose In various cerebrovascular diseases the visualization of individual arteries and knowledge about their hemodynamic properties, like flow velocity and direction, can become important for an accurate diagnosis. Magnetic resonance angiography methods are intended to acquire this information, but often a single acquisition is not sufficient to retrieve all of this desired information. Methods Using selective arterial spin labeling (ASL) methods, a single artery of interest can be tagged and visualized, whereas quantitative information about hemodynamics can be retrieved using phase-contrast techniques that are often limited regarding their selectivity. In this study, a method that allows for velocity mapping of individual arteries by incorporating phase-contrast preparation into selective ASL angiography measurements is presented. Several postprocessing steps are required to generate velocity and directional-encoded maps of selected arteries from the data acquired in a single scan. Results The method was successfully evaluated in healthy volunteers, and a first application in two selected patients is presented. In one patient, an aneurysm of the middle cerebral artery is investigated, and in the second patient it is used to visualize an arterio-venous malformation. Conclusion Selective ASL imaging in conjunction with phase-contrast acquisition allows for investigating hemodynamic properties of individual arteries. Magn Reson Med, 2016. © 2016 International Society for Magnetic Resonance in Medicine.

To accelerate super-selective arterial spin labeling (ASL) angiography by using a single control condition denoted as cycled super-selective arterial spin labeling. A single non-selective control image is acquired that is shared by selective label images. Artery-selective imaging is possible by geometrically changing the position of the labeling focus to more than one artery of interest during measurement. The presented approach is compared to conventional super-selective imaging in terms of its labeling efficiency inside and outside the labeling focus using numerical simulations and in vivo measurements. Additionally, the signal-to-noise ratios of the images are compared to non-selective ASL angiography and analyzed using a two-way ANOVA test and calculating the Pearson’s correlation coefficients. The results indicate that the labeling efficiency is not reduced within the labeled artery, but can increase as a function of distance to the artery of interest when compared to conventional super-selective ASL. In the final images, no statistically significant difference of image quality can be observed while the acquisition duration could be reduced when the major brain feeding arteries are being tagged. Using super-selective arterial spin labeling, a single non-selective control acquisition suffices for reconstructing selective angiograms of the cerebral vasculature, thereby accelerating image acquisition of the major intracranial arteries without notable loss of information.

We present the first case report describing a craniotomy for a glioblastoma in a patient with hemihydranencephaly (HHE). Ten years ago our patient had average cognitive and language functions, indicating very good adaption of his single right hemisphere. Due to the tumour he developed a deceleration, deficits in language functions and mild impairments of basic cognitive functions. Further neuroplastic reorganisations of his right hemisphere in response to the tumour growth are discussed. The favourable postoperative outcome supported the decision for careful tumour resection in this patient with HHE.

The purpose of our study was to compare the agreement of both the total Alberta Stroke Program Early CT Score (ASPECTS) and region-based scores from two automated ASPECTS software packages and an expert consensus (EC) reading with final ASPECTS in a selected cohort of patients who had prompt reperfusion from endovascular thrombectomy (EVT). ASPECTS were retrospectively and blindly assessed by two software packages and EC on baseline non-contrast-enhanced computed tomography (NCCT) images. All patients had multimodal CT imaging including NCCT, CT angiography, and CT perfusion which demonstrated an acute anterior circulation ischemic stroke with a large vessel occlusion. Final ASPECTS on follow-up scans in patients who had EVT and achieved complete reperfusion within 100 min from NCCT served as ground truth and were compared to total and region-based scores. Fifty-two patients met our study criteria. Moderate agreement was obtained between both software packages and EC for total ASPECTS and there was no significant difference in overall performance. However, the software packages differed with respect to regional contribution. In this cohort, the majority of infarcted regions were deep structures. Package A was more sensitive in cortical areas than the other methods, but at a cost of specificity. EC and software package B had greater sensitivity, but lower specificity for deep brain structures. In this cohort, using the final ASPECTS as ground truth, no clinically significant difference was observed for total ASPECT score between human or automated packages, but there were differences in the characteristics of the regions scored. • Some national stroke guidelines have incorporated ASPECTS in their recommendations for selecting patients for endovascular therapy. • Computer-aided diagnosis is a promising tool to aid the evaluation of early ischemic changes identified on CT. • Software packages for automated ASPECTS assessment differed significantly with respect to regional contribution without any significant difference in the overall ASPECT score.

Various stent retrievers differing in stent design and mechanical properties are currently available for the treatment of ischemic stroke. We conducted this in vitro study to compare the efficacy, embolism rate, and safety of commercially available stent retrievers and prototypes. Whole blood thrombi were produced in a Chandler loop. The thrombi were inserted into the curved M1 segment of a silicone model of the anterior cerebral circulation. Thrombectomy maneuvers were performed with six commercially available stent retrievers and 2 prototypes with different strut thickness. Wall-stent apposition, first pass recanalization rate, retraction force, and embolism rate were compared. Devices with complete wall-stent apposition had the highest first pass recanalization rate and lowest embolism rate, but showed the highest retraction force. The prototype with thinner struts had a comparable recanalization and embolism rate, while a lower retraction force had to be applied compared to the prototype with thicker struts. Complete wall-stent apposition facilitates a higher recanalization rate and lower embolism rate but also correlates to a higher necessary retraction force and thus possibly higher risk of endothelium damage. Stent modifications leading to a reduced retraction force do not compromise efficacy and embolism rate. · Complete wall-stent apposition facilitates an effective thrombectomy. · Complete wall-stent apposition leads to higher retraction force and possibly greater endothelium damage. · Modifications of strut thickness do not compromise recanalization and embolism rate. · Thinner struts correlate with a lower retraction force.· Larsen N, Oberbeck K, Lima de Miranda R et al. Comparison of Efficacy, Embolism Rate and Safety of Thrombectomy with Stent Retrievers in an Anterior Circulation Stroke Model. Fortschr Röntgenstr 2018; 190: 1053 - 1058.ZIEL: In der Therapie des ischämischen Schlaganfalles kommen verschiedene Stentretriever zum Einsatz, die sich in Stentdesign und mechanischen Eigenschaften unterscheiden. Wir führten diese in vitro-Studie durch, um Effektivität, Embolisationsrate und notwendige Retraktionskraft von kommerziell erhältlichen Stentretrievern und zwei Prototypen zu vergleichen. In einem Chandler loop generierte Vollblutthromben wurden in das bogig verlaufende M1-Segment eines Silikonmodells der vorderen intrakraniellen Zirkulation eingebracht. Thrombektomiemanöver wurden mit 6 kommerziell erhältlichen Stentretrievern und 2 Prototypen, die sich in der Stärke der Stentstreben unterschieden, durchgeführt. Die Adaptation des Stentretrievers an die Gefäßwand, first pass-Rekanalisierungsrate, Retraktionskraft und Embolisationsrate wurden verglichen. Die Stentretriever, die eine vollständige Adaptation an die Gefäßwand zeigten, wiesen eine höhere first pass-Rekanalisierungsrate und geringere Embolisationsrate auf als Stentretriever, die sich nicht in voller Länge an die Gefäßwand anlegten. Andererseits war bei ersteren eine höhere Retraktionskraft notwendig. Der Prototyp mit dünneren Stentstreben erreichte eine vergleichbare Rekanalisations- und Embolierate bei geringerer aufzuwendender Retraktionskraft im Vergleich zum Prototypen mit stärkeren Stentstreben. Eine vollständige Adaptation des Stentretrievers an die Gefäßwand ermöglicht eine effektive Thrombektomie mit geringer Embolierate, ist jedoch mit einer höheren notwendigen Retraktionskraft und damit potentiell höheren Gefahr einer Endothelverletzung verbunden. Veränderungen des Stentdesigns in den Prototypen mit Verminderung der Stärke der Stentstreben führen zu einer geringeren Retraktionskraft, beeinträchtigten jedoch nicht die Rekanalisierungs- und Embolierate. · Die vollständige Adaptation des Stentretrievers an die Gefäßwand ermöglicht eine effektive Thrombektomie. · Diese ist mit einer höheren Retraktionskraft und möglicherweise Gefahr der Endothelverletzung verbunden. · Durch Verringerung der Strebendicke wird die Rekanalisations- und Embolierate nicht beeinträchtigt. · Die Retraktionskraft kann hierdurch vermindert werden.

Magnetic resonance imaging (MRI) is a sensitive imaging tool which lacks the burden of ionizing radiation. It is not established as primary diagnostic tool in traumatic brain injury (TBI). The purpose of this study was to evaluate the usefulness of MRI as initial imaging modality in the emergency management of mild pediatric TBI. Children (0–18 years, sub-divided in four age-groups) with mild TBI who received MRI in the emergency department were identified. Clinical characteristics and trauma mechanisms were evaluated retrospectively. Univariate and multivariate logistic regression analyses were used to identify clinical factors that might be indicative for trauma sequelae on MRI scans. An institutional case series of 569 patients (322 male/247 female; age

I denne masterutredningen er formålet å verdsette egenkapitalverdien til Netflix, Inc. Vi benytter fundamental verdsettelse som verdsettelsesteknikk, og det blir dermed tatt utgangspunkt i underliggende økonomiske forhold for å estimere fremtidige kontantstrømmer. Disse diskonteres så med utledede avkastningskrav for å komme frem til et verdiestimat per aksje. For å analysere de underliggende økonomiske forholdene er det gjennomført en kvalitativ analyse basert på bransje- og selskapsspesifikke forhold. Hovedfunnene fra analysen er at videounderholdningsbransjen har opplevd høy vekst i senere år og konkurranseintensiteten klassifiseres som moderat. Herunder utgjør høye inngangsbarrierer en viktig faktor for å holde konkurransen på dette nivået, og for at dette skal vedvare er bransjen avhengig av å etterfølge den teknologiske utviklingen. Trusselen fra substitutter må også overkommes, og da særlig piratkopiering, ved å blant annet tilby et bedre kost/nytte-forhold. Vi argumenterer videre for at Netflix sitt mangfoldige innholdsbibliotek og unike innovasjonskultur kan gi opphav til varige, beholdte konkurransefortrinn og dermed danne en strategisk fordel på lang sikt. Den strategiske analysen er videre kombinert med en kvantitativ analyse som tar utgangspunkt i offentliggjorte regnskapstall. I regnskapsanalysen omgrupperes Netflix sitt regnskap. Dette settes så opp mot videounderholdningsbransjens regnskap, gjennom en risiko- og lønnsomhetsanalyse. Vi finner at Netflix har god likviditet, men at soliditeten er noe presset sett i forhold til bransjen. Videre finner vi at Netflix har en driftsfordel på 2,5% basert på et tidsvektet gjennomsnitt, men grunnet en negativ finansieringsfordel har imidlertid selskapet en svak strategisk ulempe på 1,4%. Med utgangspunkt i den strategiske analysen og regnskapsanalysen utarbeides et fremtidsregnskap. Basert på dette estimeres Netflix sin egenkapitalverdi ved å diskontere kontantstrømmene med avkastningskravet. Ved å deretter gjennomføre en simulerings- og sensitivitetsanalyse reflekteres usikkerheten i verdiestimatet. For å foreta en rimelighetsvurdering av verdiestimatet gjennomfører vi avslutningsvis en komparativ verdsettelse som baserer seg på sammenlignbare selskaper. Det endelige verdiestimatet til Netflix estimeres til 134,9 USD per aksje per 24.04.17, mens aksjekursen er på 143,8 USD. Handelsstrategien vår tilsier således en holdanbefaling. nhhmas

Background In aneurysmal subarachnoid haemorrhage cerebral vasospasm leads to clinical worsening and poor outcome. Interventional treatment with nimodipine might be a therapeutic option. Objective To evaluate the clinical course of patients with different interventional treatment types. Methods A retrospective, observational analysis was performed. Inclusion criteria were aneurysmal subarachnoid haemorrhage, clinical and/or radiologic evidence of vasospasm and interventional intra-arterial treatment. Patients were divided into 3 groups: continuous nimodipine infusion, repetitive nimodipine infusions, and singular nimodipine infusion. Pre- and postinterventional parameters were analyzed to evaluate the efficacy of the procedure in terms of responder status. Outcome was determined using the modified Rankin scale. Results A total of 163 interventions (97 patients) were examined. Patients with continuous treatment showed a greater World Federation of Neurological Surgeons grade. Response to intra-arterial nimodipine in the continuous group was comparatively worse. Transcranial Doppler monitoring as well as brain tissue oxygenation measuring showed good correlation with imaging results. The rate of intraprocedural complications in the continuous treatment group was significantly greater. We observed a worse clinical outcome in the patients who underwent continuous treatment. None of the patients in the continuous group achieved favorable outcome after 3 months. Conclusions Facing the poor clinical outcome and the greater complication rate, continuous intra-arterial infusion of nimodipine in patients with angiographically refractory cerebral vasospasm has to be indicated strictly. Transcranial Doppler and brain tissue oxygenation monitoring seem to be reliable tools for evaluation of the clinical postinterventional course.