Automated detection and segmentation of intracranial hemorrhage suspect hyperdensities in non-contrast-enhanced CT scans of acute stroke patients.

OBJECTIVES: Artif icial intelligence (AI)-based image analysis is increasingly applied in the acute stroke field. Its implementation for the detection and quantification of hemorrhage suspect hyperdensities in non-contrast-enhanced head CT (NCCT) scans may facilitate clinical decision-making and accelerate stroke management. METHODS: NCCTs of 160 patients with suspected acute stroke were analyzed regarding the presence or absence of acute intracranial hemorrhages (ICH) using a novel AI-based algorithm. Read was performed by two blinded neuroradiology residents (R1 and R2). Ground truth was established by an expert neuroradiologist. Specificity, sensitivity, and area under the curve were calculated for ICH and intraparenchymal hemorrhage (IPH) detection. IPH-volumes were segmented and quantified automatically by the algorithm and semi-automatically. Intraclass correlation coefficient (ICC) and Dice coefficient (DC) were calculated. RESULTS: In total, 79 of 160 patients showed acute ICH, while 47 had IPH. Sensitivity and specificity for ICH detection were 0.91 and 0.89 for the algorithm; 0.99 and 0.98 for R1; and 1.00 and 0.98 for R2. Sensitivity and specificity for IPH detection were 0.98 and 0.89 for the algorithm; 0.83 and 0.99 for R1; and 0.91 and 0.99 for R2. Interreader reliability for ICH and IPH detection showed strong agreements for the algorithm (0.80 and 0.84), R1 (0.96 and 0.84), and R2 (0.98 and 0.92), respectively. ICC indicated an excellent (0.98) agreement between the algorithm and the reference standard of the IPH-volumes. The mean DC was 0.82. CONCLUSION: The AI-based algorithm reliably assessed the presence or absence of acute ICHs in this dataset and quantified IPH volumes precisely. KEY POINTS: • Artificial intelligence (AI) is able to detect hyperdense volumes on brain CTs reliably. • Sensitivity and specificity are highest for the detection of intraparenchymal hemorrhages. • Interreader reliability for hemorrhage detection shows strong agreement for AI and human readers.

Risk factors associated with progressive lacunar strokes and benefit from dual antiplatelet therapy.

BACKGROUND AND PURPOSE: Early neurological deterioration (END) occurs in 20%-30% of patients with lacunar stroke and challenges their clinical management. This retrospective cohort study analyzed clinical and neuroimaging risk factors predicting the occurrence of END, the functional outcome after END and potential benefit from dual antiplatelet therapy (DAPT) in patients with lacunar strokes. METHODS: Factors associated with END and benefit from DAPT were retrospectively analyzed in 308 patients with lacunar stroke symptoms and detected lacunar infarction by magnetic resonance imaging. END was defined by deterioration of ≥3 total National Institutes of Health Stroke Scale (NIHSS) points, ≥2 NIHSS points for limb paresis or documented deterioration within 5 days after admission. Patients were treated with DAPT according to in-house standards. The primary efficacy end-point for functional outcome was fulfilled if NIHSS at discharge improved after END at least to the score at admission. RESULTS: Male gender [odds ratio (OR) 2.08; 95% confidence interval (CI) 1.09-4.00], higher age (OR = 1.65 per 10 years; 95% CI 1.18-2.31), motor paresis (OR = 18.89, 95% CI 4.66-76.57) and infarction of the internal capsule or basal ganglia (OR = 3.58, 95% CI 1.26-10.14) were associated with an increased risk for END. A larger diameter of infarction (OR = 0.85, 95% CI 0.76-0.95), more microangiopathic lesions (OR = 0.75, 95% CI 0.57-0.99) and pontine localization (OR = 0.29, 95% CI 0.12-0.65) were factors associated with unfavorable functional outcome after END occurred. Localization in the internal capsule or basal ganglia was identified as a significant predictive factor for a benefit from DAPT after END. CONCLUSIONS: Identified clinical and neuroimaging factors predicting END occurrence, functional outcome after END and potential benefit from DAPT might improve the clinical management of patients with lacunar strokes.

Frequency and temporal profile of recanalization after cerebral vein and sinus thrombosis.

BACKGROUND AND PURPOSE: The temporal course of recanalization and its association with clinical outcome were analysed in our patients with cerebral sinus and/or venous thrombosis (CSVT) and follow-up magnetic resonance imaging (MRI). METHODS: Between January 1998 and September 2014 all patients from our institutions with CSVT were systematically analysed. Baseline data, treatment characteristics and follow-up MRI were retrospectively recorded. The status of recanalization was assessed as complete (CRec), partial (PRec) or failed recanalization. Clinical follow-up was measured with the modified Rankin Scale. Excellent outcome was defined as modified Rankin Scale 0-1. RESULTS: Ninety-nine patients were identified; 97% of these patients were treated with oral anticoagulation (OAC) and the median (min-max) time of OAC was 7 months (1-84). CRec was achieved in 57.6% (57/99), PRec in 29.3% (29/99) and only 13 (13.1%) patients did not recanalize. The median (min-max) time to PRec was 4 months (0.25-14) and to CRec 6 months (2-34). Median time to last clinical follow-up was 8 months (1-88); 91.8% (89/99) had an excellent outcome at last clinical follow-up and only 2.1% (2/99) died. Only thrombosis of the superior sagittal sinus was independently associated with successful recanalization (odds ratio 16, 95% confidence interval 2-138). No severe haemorrhagic complications and no recurrence of CSVT occurred within clinical follow-up. No association of outcome and recanalization status was found. CONCLUSIONS: The recanalization rate of CSVT under OAC was high and the median time to CRec was 6 months. Thrombosis of the superior sagittal sinus is a positive predictor of recanalization. Outcome in this cohort was excellent but no significant association of outcome and recanalization status was found.

Effect of thrombus size on recanalization by bridging intravenous thrombolysis.

BACKGROUND AND PURPOSE: Thrombus length has been reported as an important predictor of successful recanalization by intravenous thrombolysis but its influence on bridging thrombolysis has not been investigated yet. The effect of thrombus length on recanalization rates evaluated by catheter angiography early after intravenous bridging thrombolysis was analyzed. METHODS: Ninety-six consecutive patients with acute cerebral artery occlusion were included. Occlusion site and thrombus length on initial computed tomography angiography or magnetic resonance angiography were related to recanalization after intravenous bridging thrombolysis on the initial series of catheter angiography. RESULTS: Eleven of 96 patients (11.5%) showed successful recanalization (TICI 2a, 2b or 3) after intravenous bridging thrombolysis. Mean thrombus length in these patients was 10.8 mm as opposed to 15.6 mm in patients without successful recanalization. No thrombus longer than 16 mm showed complete recanalization. Binary logistic regression demonstrated a significant influence of thrombus length on probability of recanalization (odds ratio 0.78, 95% confidence interval 0.65-0.95; P = 0.014). CONCLUSIONS: Thrombus length is a significant predictor of recanalization rates after bridging thrombolysis. Overall recanalization rate within the time frame until interventional treatment is started was 11.5% after bridging thrombolysis.

The LVIS Jr. microstent to assist coil embolization of wide-neck intracranial aneurysms: clinical study to assess safety and efficacy.

INTRODUCTION: This study was aimed to assess clinical safety and efficacy of the LVIS Jr. microstent in stent-assisted coil embolization of wide-neck intracranial aneurysms. METHODS: IRB approved single-center interventional clinical study in 22 patients (10 females, 12 males, mean age 55, age range 33-74 years) for the endovascular treatment of wide-neck aneurysms. After obtaining informed consent, patients were included according to the following criteria: aneurysm fundus-to-neck ratio < 2 or neck diameter > 4 mm, and a parent vessel diameter of ≤3.5 mm. Primary end point for clinical safety was absence of death, absence of major or minor stroke, and absence of transient ischemic attack. Primary end point for treatment efficacy was complete angiographic occlusion according to the Raymond-Roy Occlusion Classification (RROC) immediately after the procedure and at follow-up after 3 and 6 months on magnetic resonance imaging (MRI). RESULTS: In 20/22 (91 %) of patients, the primary end point of safety was reached; in the two remaining patients, transient ischemic attack, but no permanent deficit was observed; in 16/22 (73 %), efficient occlusion (RROC1) was reached, and in 6/22 (27 %), a residual neck remained (RROC2). Single [seven with antegrade, two in crossover configuration, and four with "first-balloon-then-stent" (FBTS) technique] or double-stent (eight patients with Y configuration and one patient with X configuration) deployment was technically successful in all cases. CONCLUSION: Deployment of the LVIS Jr. microstent in various single- or double-stent configurations is safe and effective to assist the treatment of intracranial wide-neck aneurysms.

[Clinical course of cerebral sinus venous thrombosis. Data from a monocentric cohort study over 15 years]. / Verlauf der zerebralen Sinus-/Venenthrombose. Daten einer monozentrischen Kohortenstudie über 15 Jahre.

INTRODUCTION: Thrombosis of cerebral veins or sinuses (CVST) is a rare condition. In a monocentric retrospective cohort study the clinical characteristics, risk factors, radiological findings as well as course and prognosis of patients over the past 15 years were examined. METHODS: Between January 1998 and March 2013 all patients who were treated as inpatients for CVST at the department of neurology of the University of Heidelberg were systematically registered in a database. Along with all relevant clinical data the modified Rankin scale (MRS) was used to measure the clinical severity. A follow-up visit was performed at three time points. The odds ratios (OR) were calculated to establish predictors of good outcome (MRS 0-2), mortality at discharge and at follow-up. Significant variables after univariate analysis were tested for independency in a multivariate logistic regression model. RESULTS: A total of 143 patients were included in the study. The median age was 43 years (range 17-74 years) and 67.4 % of patients were female. The most common symptoms were headache (70.6 %), seizures (50.4 %) and paresis (37.8 %). The most prominent clinical risk factor was oral contraception (40.4 %). The two most common localizations of thrombosis were the transversal sinus with the sigmoid sinus (66.4 %) and the sagittal superior sinus (47.6 %). On admission 42.7 % of patients suffered additionally from intracerebral hemorrhage and 12.6 % from congestive infarction. Of the patients 9.5 % (10 out of 105) showed a pathologically reduced activated protein C (APC) resistance and 8.4 % (6 out of 94) a prothrombin mutation. All patients were initially treated with heparin and 88.7 % were switched to cumarin during the course of the disease. The median duration of anticoagulation was 15.75 months (range 1-121 months). On discharge 77.7 % had a good outcome and the in-hospital mortality was 4.7 %. The median time to follow-up in 108 patients was 36 months (range 3-132 months), 74.1 % of patients had a good outcome (MRS 0-2) and 18.5 % died. Independent predictors of in-hospital mortality were MRS on admission (OR 2.2, 95 % CI 1.03-4.7) and of mortality at follow-up the presence of a malignant disease (OR 50.2, 6-423) and intracerebral hemorrhage on admission (OR 10.3, 1.7-62.6). DISCUSSION: The results of this study are in line with previously published data on CVST. The most prominent clinical risk factors for CVST were female gender and oral contraception. At discharge from hospital and 3 years after CVST approximately 75 % of patients achieved a good clinical outcome. A severe clinical syndrome and the presence of an intracerebral hemorrhage on admission were independent predictors of mortality.

Quantitative high-field diffusion tensor imaging of cerebral white matter in asymptomatic high-grade internal carotid artery stenosis.

BACKGROUND: Recently, several studies using diffusion-sensitized MRI reported changes in patients with high-grade internal carotid artery stenosis (ICAS) suggestive of subtle brain tissue damage. We used diffusion tensor imaging (DTI) to investigate the microstructural cerebral white matter integrity in asymptomatic patients with high-grade ICAS. METHODS: In 15 asymptomatic patients with unilateral high grade (>70%) ICAS, we used 3T MRI including DTI. We used a region-of-interest approach comparing quantitative DTI metrics between both hemispheres including the so-called border zones. MR images were also assessed for periventricular white matter lesions (PWML) as well as collaterals via the circle of Willis. RESULTS: There was no significant intraindividual difference of fractional anisotropy or mean diffusivity values between the hemispheres for any region. PWML was graded 0° in 6 patients, I° in 9 and II° in 2. CONCLUSIONS: In clinically asymptomatic patients with high-grade unilateral ICAS, there was no difference between the DTI parameters of the affected and the unaffected hemisphere. These findings contrast with other studies in asymptomatic high-grade ICAS, which is likely due to patient selection. These findings argue against concomitant chronic tissue integrity changes and implicate the benignity of asymptomatic carotid artery disease in individual patients.

RAPID CT Perfusion-Based Relative CBF Identifies Good Collateral Status Better Than Hypoperfusion Intensity Ratio, CBV-Index, and Time-to-Maximum in Anterior Circulation Stroke.

BACKGROUND AND PURPOSE: Information of collateral flow may help to determine eligibility for thrombectomy. Our aim was to identify CT perfusion-based surrogate parameters of good collateral status in acute anterior circulation ischemic stroke. MATERIALS AND METHODS: In this retrospective study, we assessed the collateral status of 214 patients who presented with acute ischemic stroke due to occlusion of the MCA M1 segment or the carotid terminus. Collaterals were assessed on dynamic CTA images analogous to the multiphase CTA score by Menon et al. CT perfusion parameters (time-to-maximum, relative CBF, hypoperfusion intensity ratio, and CBV-index) were assessed with RAPID software. The Spearman rank correlation and receiver operating characteristic analyses were performed to identify the parameters that correlate with collateral scores and good collateral supply (defined as a collateral score of ≥4). RESULTS: The Spearman rank correlation was highest for a relative CBF < 38% volume (ρ = -0.66, P < .001), followed by the hypoperfusion intensity ratio (ρ = -0.49, P < .001), CBV-index (ρ = 0.51, P < .001), and time-to-maximum > 8 seconds (ρ = -0.54, P < .001). Good collateral status was better identified by a relative CBF < 38% at a lesion size <27 mL (sensitivity of 75%, specificity of 80%) compared with a hypoperfusion intensity ratio of <0.4 (sensitivity of 75%, specificity of 62%), CBV-index of >0.8 (sensitivity of 60%, specificity of 78%), and time-to-maximum > 8 seconds (sensitivity of 68%, specificity of 76%). CONCLUSIONS: Automated CT perfusion analysis allows accurate identification of collateral status in acute ischemic stroke. A relative CBF < 38% may be a better perfusion-based indicator of good collateral supply compared with time-to-maximum, the hypoperfusion intensity ratio, and the CBV-index.

Accuracy and Prognostic Role of NCCT-ASPECTS Depend on Time from Acute Stroke Symptom-onset for both Human and Machine-learning Based Evaluation.

PURPOSE: We hypothesize that the detectability of early ischemic changes on non-contrast computed tomography (NCCT) is limited in hyperacute stroke for both human and machine-learning based evaluation. In short onset-time-to-imaging (OTI), the CT angiography collateral status may identify fast stroke progressors better than early ischemic changes quantified by ASPECTS. METHODS: In this retrospective, monocenter study, CT angiography collaterals (Tan score) and ASPECTS on acute and follow-up NCCT were evaluated by two raters. Additionally, a machine-learning algorithm evaluated the ASPECTS scale on the NCCT (e-ASPECTS). In this study 136 patients from 03/2015 to 12/2019 with occlusion of the main segment of the middle cerebral artery, with a defined symptom-onset-time and successful mechanical thrombectomy (MT) (modified treatment in cerebral infarction score mTICI = 2c or 3) were evaluated. RESULTS: Agreement between acute and follow-up ASPECTS were found to depend on OTI for both human (Intraclass correlation coefficient, ICC = 0.43 for OTI < 100 min, ICC = 0.57 for OTI 100-200 min, ICC = 0.81 for OTI ≥ 200 min) and machine-learning based ASPECTS evaluation (ICC = 0.24 for OTI < 100 min, ICC = 0.61 for OTI 100-200 min, ICC = 0.63 for OTI ≥ 200 min). The same applied to the interrater reliability. Collaterals were predictors of a favorable clinical outcome especially in hyperacute stroke with OTI < 100 min (collaterals: OR = 5.67 CI = 2.38-17.8, p < 0.001; ASPECTS: OR = 1.44, CI = 0.91-2.65, p = 0.15) while ASPECTS was in prolonged OTI ≥ 200 min (collaterals OR = 4.21,CI = 1.36-21.9, p = 0.03; ASPECTS: OR = 2.85, CI = 1.46-7.46, p = 0.01). CONCLUSION: The accuracy and reliability of NCCT-ASPECTS are time dependent for both human and machine-learning based evaluation, indicating reduced detectability of fast stroke progressors by NCCT. In hyperacute stroke, collateral status from CT-angiography may help for a better prognosis on clinical outcome and explain the occurrence of futile recanalization.

[Intensive care management [corrected] of patients with intracerebral hemorrhage]. / Intensivmedizinische Versorgung von Patienten mit intrazerebraler Blutung.

Approximately 10-15% of acute strokes are caused by non-aneurysmatic intracerebral hemorrhage (ICH) and incidences are expected to increase due to an aging population. Studies from the 1990s estimated mortality of ICH to be as high as 50%. However, these figures may partly be attributed to the fact that patients suffering from ICH frequently received only supportive therapy and the poor prognosis may therefore be more a self-fulfilling prophecy. Recently it has been shown that treatment in a specialized neurological intensive care unit alone was associated with better outcomes after ICH. In recent years considerable efforts have been undertaken in order to develop new therapies for ICH and to assess them in randomized controlled trials. Apart from admission status, hemorrhage volume is considered to be the main prognostic factor and impeding the spread of the hematoma is thus a basic therapeutic principle. The use of activated factor VIIa (aFVIIa) to stop hematoma enlargement has been assessed in two large randomized controlled trials, however the promising results of the dose-finding study could not be confirmed in a phase III trial. Although hemostatic therapy with aFVIIa reduced growth of the hematoma it failed to improve clinical outcome. Similar results were found in a randomized controlled trial on blood pressure management in acute ICH. The link between reduction of hematoma growth and improved outcome is therefore still lacking. Likewise the value of surgical hematoma evacuation remains uncertain. In the largest randomized controlled trial on surgical treatment in ICH so far, only a small subgroup of patients with superficial hemorrhages seemed to benefit from hematoma evacuation. Whether improved intensive care can contribute to improved outcome after ICH will be shown by data obtained in the coming years.

Vasogenic Brain Edema During Maintenance Hemodialysis : Preliminary Results from Tract-based Spatial Statistics and Voxel-based Morphometry.

BACKGROUND: Hemodialysis (HD), especially when first initiated, can cause neurological deterioration. Presumably this is due to transient cerebral edema, which has been observed using diffusion weighted magnetic resonance imaging (MRI) in experimental and human studies; however, this has not been investigated under maintenance hemodialysis (mHD). Moreover, there are no studies to date investigating regional effects of mHD on grey and white matter volumes. METHODS: In this study eight patients with end stage renal disease (ESRD) were examined immediately before and after mHD sessions with multimodal MRI, including diffusion tensor imaging (DTI) and high-resolution structural imaging. Additionally, eight healthy, age-matched and sex-matched controls were examined for comparison. Data were analyzed using tract-based spatial statistics and voxel-based morphometry. RESULTS: At baseline, ESRD patients had significantly reduced values of fractional anisotropy (FA) and axial diffusivity as well as bilaterally reduced grey matter volume in the insula, compared with controls. After the mHD session, FA further decreased while axial, radial, and mean diffusivity significantly increased ubiquitously throughout the white matter. Voxel-based morphometry revealed a corresponding significant increase in white matter volume in the central right hemisphere and splenium, as well as in cortical grey matter in the anterior medial frontal and cingulate cortex. None of the patients showed neurological deterioration. CONCLUSION: In this study ESRD patients showed white matter changes indicative of chronic microstructural damage when compared with healthy controls, as previously reported. In addition, patients showed signs of a transient extracellular cerebral edema, which has not yet been observed in the absence of neurological symptoms.

Periprocedural Safety and Feasibility of the New LVIS EVO Device for Stent-Assisted Coiling of Intracranial Aneurysms: An Observational Multicenter Study.

BACKGROUND AND PURPOSE: Stent-assisted treatment techniques can be an effective treatment option for intracranial aneurysms. The aim of this study was to evaluate the periprocedural feasibility and safety of the new LVIS EVO stent for the treatment of intracranial aneurysms. MATERIALS AND METHODS: Patients with intracranial aneurysms treated with the LVIS EVO in 11 European neurovascular centers were retrospectively reviewed. Patient and aneurysm characteristics, procedural parameters, immediate grade of occlusion, and technical and clinical complications were assessed. RESULTS: Fifty-seven patients with 59 aneurysms were treated with the LVIS EVO device; 57.6% of the aneurysms were incidental; 15.3% were acutely ruptured; 15.3% were recanalized or residual aneurysms; and 11.9% were treated for symptoms other than acute hemorrhage. The most frequent aneurysm locations were the middle cerebral artery (25.4%) and the anterior communicating artery (22.0%). The rate of immediate successful deployment was 93.2%. In 6.8% (n = 4) of cases, additional in-stent angioplasty was needed. The immediate complete occlusion rate was 54.2%, while there was a residual aneurysm in 35.6% and a residual neck in 10.2%. Periprocedural technical complications occurred in 7/59 treatments (11.9%; the most frequent technical complication [n = 3] was thrombus formation), which all resolved completely without clinical sequelae. Postprocedural neurologic complications occurred after 4/59 treatments (6.8%; 2 transient ischemic attacks, 1 minor stroke, 1 major stroke), of which only 1 persistent complication was directly related to the procedure (minor stroke in the vascular territory distal to the stent). CONCLUSIONS: The LVIS EVO stent is a safe, feasible device for the treatment of intracranial aneurysms.

DTI of commissural fibers in patients with Chiari II-malformation.

Chiari II-malformation is a complex congenital deformity of the brain which is frequently associated with hydrocephalus. Abnormalities of the corpus callosum are known to occur in the majority of patients. The objective of the present study was to study the microstructure of the corpus callosum (CC) and the anterior commissure (AC) to differentiate between different mechanisms of damage to these structures. We investigated 6 patients with Chiari II-malformation and 6 well-matched healthy volunteers employing T1-weighted 3D imaging and diffusion tensor imaging (DTI) to determine the fractional anisotropy (FA) and cross-sectional area of the CC and AC, as well as with neuropsychological testing. Four patients showed hydrocephalus, two patients had callosal dysplasia and four had a hypoplastic CC. The callosal FA in the patients was significantly reduced which was less pronounced for the genu alone. The area of CC was also reduced in Chiari II-patients. There was a strong correlation between the size and FA of the CC in the patients. In contrast, the thickness of the AC was significantly increased and was associated with higher FA in the patients. In psychological tests all patients showed reduced verbal memory; all but one patient showed reduced IQ as well as impaired visuo-spatial performance, indicating deficits in tasks requiring parieto-occipital integration. The existence of callosal dysplasia in two patients, the diminished FA reduction in the genu and the correlation of the cross-sectional area and FA in the patients point to a developmental white matter damage beside that exerted by hydrocephalus alone.

Clinical Outcome after Thrombectomy in Patients with Stroke with Premorbid Modified Rankin Scale Scores of 3 and 4: A Cohort Study with 136 Patients.

BACKGROUND AND PURPOSE: We aimed to analyze the clinical outcome after mechanical thrombectomy in patients with premorbid mRS 3 and 4 because there are currently no data on this patient group. MATERIALS AND METHODS: Between January 2009 and November 2017, all patients with premorbid mRS 3 or 4 undergoing mechanical thrombectomy due to anterior circulation stroke were selected. Good outcome was defined as a clinical recovery to the status before stroke onset (ie, equal premorbid mRS and mRS at 90 days). In addition, mortality at discharge and at 90 days was analyzed. RESULTS: One hundred thirty-six patients were included, of whom 81.6% presented with premorbid mRS 3; and 18.4%, with premorbid mRS 4; 24.0% of patients with premorbid mRS 4 achieved clinical recovery compared with 20.7% of patients with premorbid mRS 3 (P = .788). However, the proportion of hospital mortality and mortality at 90 days was nonsignificant, but markedly higher in patients with premorbid mRS 4. Multivariate analysis identified low NIHSS scores (OR, 0.92; 95% CI, 0.85-0.99; P = .040), high ASPECTS (OR, 1.45; 95% CI, 1.02-2.16; P = .049), and TICI 2b-3 (OR, 7.11; 95% CI, 1.73-49.90; P = .017) as independent predictors of good outcome. CONCLUSIONS: Good outcome in patients with premorbid mRS 3 and 4 is less frequent compared with premorbid mRS 0-2. Nevertheless, about 20% of the patients return to their premorbid mRS, which may justify endovascular treatment. The most important predictor of good outcome is successful recanalization.

The Influence of Angioarchitectural Features on the Success of Endovascular Embolization of Cranial Dural Arteriovenous Fistulas with Onyx.

BACKGROUND AND PURPOSE: Endovascular embolization can be an effective treatment for cranial dural arteriovenous fistulas. However, a considerable number of dural arteriovenous fistulas still cannot be treated sufficiently. The purpose of this study was to report our single-center experience of endovascular embolization of dural arteriovenous fistulas with Onyx, including the investigation of the influence of angioarchitectural features on the treatment success. MATERIALS AND METHODS: Clinical data, angioarchitectural features, complications, treatment success (defined as complete symptom remission for low-grade dural arteriovenous fistulas and complete occlusion for high-grade dural arteriovenous fistulas), and occlusion rates were assessed. The influence of various angioarchitectural features (including location, pattern of venous drainage, and quantity and origin of feeding arteries) was investigated using multivariable backward logistic regression. RESULTS: One hundred four patients with 110 dural arteriovenous fistulas were treated in 132 treatment procedures. Treatment success and complete occlusion rates were 81.8% and 90.9%, respectively. After a mean follow-up of 23.6 months, 95.5% of the patients showed complete symptom remission or symptom relief. The overall complication rate was 8.3% (4.5% asymptomatic, 2.3% transient, and 1.5% permanent complications). Logistic regression showed that ≥10 feeding arteries (P = .041) and involvement of the ascending pharyngeal artery (P = .039) significantly lowered the probability of treatment success. Treatment success tended to be lower for low-grade dural arteriovenous fistulas, Cognard type I dural arteriovenous fistulas, and dural arteriovenous fistulas with involvement of dural branches of the internal carotid artery, however without reaching statistical significance in the multivariable model. CONCLUSIONS: The presence of multiple feeding arteries and involvement of the pharyngeal artery negatively influence the treatment success of endovascular embolization of cranial dural arteriovenous fistulas with Onyx.

Fiber tracking of human brain using fourth-order tensor and high angular resolution diffusion imaging.

The accuracy of fiber tracking on the basis of diffusion tensor magnetic resonance imaging (DTI) is affected by many parameters. To increase accuracy of the tracking algorithm, we introduce DTI with a fourth-order tensor. Tensor elements comprise information obtained by high angular resolution diffusion imaging (HARDI). We further developed the flattened high rank tensor (FLAHRT) method and applied it to the measured fourth-order tensor. We then compared FLAHRT with: 1) the standard tracking algorithm using a second-order tensor; and 2) existing techniques involving the representation of conventional second-order tensor components as a weighted average of fourth-order tensor elements. Such techniques have been formulated in recent DT studies to link high-rank to low-rank Cartesian diffusion tensors (DTs). Diagonalization of the second-order tensor decomposes the tensor into three eigenvalues and three eigenvectors, which in turn are used to describe the diffusivity profile of a particular voxel. Diagonalization after application of the FLAHRT method reveals six eigenvalues and six eigentensors, resulting in a more accurate description of the anisotropy. We performed fiber tracking based on the eigenvalues and eigentensors calculated with the FLAHRT and standard methods. We could show that the FLAHRT technique gives more consistent and more accurate results even with a data set acquired in 15 directions only. The decomposition of the fourth-order tensor into six eigentensors has the potential to describe six different fiber orientations within a voxel.

Value of Contrast-Enhanced MRA versus Time-of-Flight MRA in Acute Ischemic Stroke MRI.

BACKGROUND AND PURPOSE: Vessel imaging in acute ischemic stroke is essential to select patients with large-vessel occlusion for mechanical thrombectomy. Our aim was to compare the diagnostic accuracy of time-of-flight MR angiography and contrast-enhanced MR angiography for identification of vessel occlusion and collateral status in acute ischemic stroke. MATERIALS AND METHODS: One hundred twenty-three patients with stroke with large-vessel occlusion before thrombectomy were included in this retrospective study. Before thrombectomy, 3T MR imaging, including conventional 3D TOF-MRA of the intracranial arteries and contrast-enhanced MRA of intra- and extracranial arteries, was performed. Both techniques were assessed independently by 2 neuroradiologists for location of the occlusion, imaging quality, and collateral status. Findings were compared, with subsequent DSA as the reference standard. RESULTS: Both techniques had good interrater agreement of κ = 0.74 (95% CI, 0.66-0.83) for TOF-MRA and κ = 0.72 (95% CI, 0.63-0.80) for contrast-enhanced MRA. Occlusion localization differed significantly on TOF-MRA compared with DSA (P < .001), while no significant difference was observed between DSA and contrast-enhanced MRA (P = .75). Assessment of collaterals showed very good agreement between contrast-enhanced MRA and DSA (94.9% with P = .25), but only fair agreement between TOF-MRA and DSA (23.2% with P < .001). CONCLUSIONS: Contrast-enhanced MRA offers better diagnostic accuracy than TOF-MRA in acute ischemic stroke. Contrast-enhanced MRA was superior in localizing vessel occlusion within a shorter acquisition time while providing a larger coverage, including extracranial vessels, and a more accurate assessment of collateral status. These results support inclusion of contrast-enhanced MRA in acute stroke MR imaging, perhaps making TOF-MRA superfluous.

The pCONus Device in Treatment of Wide-necked Aneurysms : Technical and Midterm Clinical and Angiographic Results.

PURPOSE: A variety of devices for treatment of wide-necked bifurcation aneurysms are emerging. Here we report our results using the new pCONus device with special emphasis on the morphological and anatomical requirements for successful implantation. METHODS: In this study we treated 21 patients with 22 aneurysms by endovascular interventions. After providing informed consent, patients were included according to the following criteria: aneurysm dome to neck ratio <2 or neck diameter >4 mm. The primary end points for clinical safety were the absence of death, absence of major or minor stroke and absence of transient ischemic attack. RESULTS: A total of 22 aneurysms in 21 patients were treated with pCONus-assisted coiling. In 19 patients harboring 20 aneurysms the implantation of the device was successful and these aneurysms showed an adequate occlusion after 6 months in 95 %. The complication rate was low (5 %) with one case of minor neurological stroke. Analysis of the data showed that the difference in aneurysm angulation between successful (mean 45°) and failed implantations (mean 71.5°) was highly significant. CONCLUSION: Use of the pCONus device and coiling in wide-necked bifurcation aneurysms is safe and provides good occlusion rates but might be limited by the angulation between the aneurysm and the parent vessel.

First Experiences with the New Enterprise2® Stent.

INTRODUCTION: Stent-assisted coiling of wide-necked intracranial aneurysms has become an established treatment and has significantly benefited from the introduction of compliant, self-expanding devices, such as the Enterprise VRD (EP-VRD). We report our experiences with the successor model, the Enterprise2 (EP2) stent in stent-assisted coiling as well as in the treatment of atherosclerotic stenosis. MATERIALS AND METHODS: In 11 consecutive patients 12 EP2 were used to treat 9 intracranial aneurysms and 2 stenoses. RESULTS: All stents could easily be delivered including partial or complete recapturing when necessary. In two cases with sharp angled curves in the carotid siphon there was kinking and flattening of the stent resulting in incomplete wall apposition of the stent. Moreover, when vascular anatomy showed curves with angles >50° it was regularly observed that the proximal stent markers were asymmetrically arranged along the vessel circumference without influence on the stent apposition. Both findings could be reproduced in a silicone flow model. CONCLUSION: The EP2 performed well in our small patient cohort; however, above a critical acute angle there may be incomplete wall apposition of the stent.

Endovascular Treatment of Dural Arteriovenous Fistulas Using Transarterial Liquid Embolization in Combination with Transvenous Balloon-Assisted Protection of the Venous Sinus.

BACKGROUND AND PURPOSE: Sinus-preserving endovascular embolization was described as a promising treatment technique for dural arteriovenous fistulas. Our aim was to report our single-center experience in patients with dural arteriovenous fistulas who were treated with transarterial liquid embolization in combination with transvenous balloon-assisted protection of the affected venous sinus. MATERIALS AND METHODS: A retrospective analysis of a prospectively collected data base was performed. Demographic and clinical data, angiographic features of the dural arteriovenous fistulas, procedural parameters, complications, treatment success, follow-up imaging, and clinical outcome were assessed. RESULTS: Twenty-two patients were treated in 25 procedures. All patients were symptomatic, of whom 81.8% presented with tinnitus; 9.1%, with ocular symptoms; and 9.1%, with headache. Most fistulas were located at the transverse and/or sigmoid sinus. The most frequent fistula type was Cognard IIa+b (40.9%), followed by Cognard I (31.8%) and Cognard IIa (27.3%)/Borden I (59.1%), followed by Borden II (40.9%). The affected sinus could be preserved in all except for 1 patient in whom it was sacrificed in a second treatment procedure by coil embolization. The overall complete occlusion rate was 86.4%. The overall complication rate was 20%, with transient and permanent morbidity and mortality of 8%, 0%, and 0%, respectively. After a mean follow-up of 18 months, most patients (68.2%) achieved complete symptom remission, 27.3% showed symptom relief, and 4.6% had stable symptoms. CONCLUSIONS: Transarterial liquid embolization of dural arteriovenous fistulas in combination with transvenous balloon-assisted protection of the venous sinus is feasible and safe and offers high rates of occlusion and of symptom remission.