Effects of inverse methods and spike phases on interictal high-density EEG source reconstruction.

OBJECTIVE: To determine the effect of inverse methods and timepoints of interictal epileptic discharges (IEDs) used for high-density electric source imaging (hd-ESI) in pharmacoresistant focal epilepsies. METHODS: We retrospectively evaluated the hd-ESI and [18F]fluorodeoxyglucose positron emission tomography (18FDG-PET) of 21 operated patients with pharmacoresistant focal epilepsy (Engel I). Volumetric hd-ESI was performed with three different inverse methods such as the inverse solution linearly constrained minimum variance (LCMV, a beamformer method), standardized low resolution electromagnetic tomography (sLORETA) and weighted minimum-norm estimation (wMNE) and at different IED phases. Hd-ESI accuracy was determined by volumetric overlap and distance between hd-ESI source maximum, as well as 18FDG-PET hypometabolic region relative to the resection zone (RZ). RESULTS: In our cohort, the shortest distances and greatest volumetric overlaps to the RZ were found in the half-rise and peak-phase for all inverse methods. The distance to the RZ was not different between the centroid of the clinical hypothesis-based cluster and the source maximum in peak-phase. However, the distance of the hypothesis-based cluster was significantly shorter compared to the cluster selected by the smallest p-value. CONCLUSIONS: Hd-ESI provides the greatest accuracy in determining the RZ at the IED half-rise and peak-phase for all applied inverse methods, whereby sLORETA and LCMV were equally accurate. SIGNIFICANCE: Our results offer guidance in selecting inverse methods and IED phases for hd-ESI, compare the performance of hd-ESI and 18FDG-PET and encourage future studies in investigating the relationship between interictal ESI and 18FDG-PET hypometabolism.

Primary Results of the Multicenter ARISE II Study (Analysis of Revascularization in Ischemic Stroke With EmboTrap).

BACKGROUND AND PURPOSE: EmboTrap is a novel stent retriever designed to achieve rapid and substantial flow restoration in acute ischemic stroke secondary to large-vessel occlusions. Here, we evaluated EmboTrap's safety and efficacy compared with established stent retrievers. METHODS: ARISE II (Analysis of Revascularization in Ischemic Stroke With EmboTrap) was a single-arm, prospective, multicenter study, comparing the EmboTrap device to a composite performance goal criterion derived using a Bayesian meta-analysis from the pivotal SWIFT (Solitaire device) and TREVO 2 (Trevo device) trials. Patients at 11 US and 8 European sites were eligible for inclusion if they had large-vessel occlusions and moderate-to-severe neurological deficits within 8 hours of symptom onset. The primary efficacy end point was achievement of modified Thrombolysis in Cerebral Ischemia (mTICI) reperfusion scores of ≥2b within 3 EmboTrap passes as adjudicated by the core laboratory. The primary safety end point was a composite of symptomatic intracerebral hemorrhage and serious adverse device effects. Secondary end points included functional independence (modified Rankin Scale, 0-2) and all-cause mortality at 90 days. RESULTS: Between October 2015 and February 2017, 227 patients were enrolled and treated with the EmboTrap device. The primary efficacy end point (mTICI ≥2b within 3 passes) was achieved in 80.2% (95% confidence interval, 74%-85% versus 56% performance goal criterion; P value, <0.0001), and mTICI 2c/3 was 65%. After all interventions, mTICI 2c/3 was achieved in 76%, and mTICI ≥2b was 92.5%. The rate of first pass (mTICI ≥2b following a single pass) was 51.5%. The primary safety end point composite rate of symptomatic intracerebral hemorrhage or serious adverse device effects was 5.3%. Functional independence and all-cause mortality at 90 days were 67% and 9%, respectively. CONCLUSIONS: The EmboTrap stent-retriever mechanical thrombectomy device demonstrated high rates of substantial reperfusion and functional independence in patients with acute ischemic stroke secondary to large-vessel occlusions. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02488915.

Pathologic validation of clot length determined using thin section non-contrast CT.

BACKGROUND AND PURPOSE: Recent studies have demonstrated that in acute ischemic stroke patients, thin section non-contrast CT (NCCT) can be used to determine the length of the hyperdense intracranial thrombus, and that clot length using this approach predicts the likelihood of vessel recanalization after intravenous tissue plasminogen activator. SUMMARY OF CASE: An acute ischemic stroke patient presented with a left middle cerebral artery occlusion and underwent emergent catheter based therapy. Clot length was determined using pretreatment thin section NCCT and was independently confirmed by the pathologist after whole clot extraction. CONCLUSIONS: The concordance between the NCCT measured clot length and the pathological examination in this case provides additional support for the accuracy of using thin section NCCT data to determine clot length in all patients.

Thin-slice reconstructions of nonenhanced CT images allow for detection of thrombus in acute stroke.

BACKGROUND AND PURPOSE: The purpose of this study was to investigate whether thin-slice image reconstructions of cranial nonenhanced CT scans could be used to significantly increase sensitivity for detecting intraluminal thrombus in patients with acute ischemic stroke due to proximal occlusion of the middle cerebral artery. METHODS: In a prospective case series, the raw data of nonenhanced CT scans from 54 patients presenting with acute ischemic stroke and proven vascular obliteration of the middle cerebral artery were collected along with the same data from patients not having a stroke but the same sex and age. All raw data were reconstructed with a slice thickness of 5 mm and as thin slices with a thickness of 0.625 mm. Three observers independently evaluated the 5-mm nonenhanced CT reconstructions and 5-mm maximum intensity projections of the thin slices and rated the likelihood of a clot obliterating the middle cerebral artery trunk or first-order branches using a 5-point scale. The results were evaluated in comparison with base data using receiver operating curve analysis. Interobserver agreement was measured using Cohen κ for every pair of observers. RESULTS: The area under the curve for the receiver operating curve analysis for the thick slices ranged from 0.63 to 0.67, whereas for the maximum intensity projection images of the thin slice reconstructions, receiver operating curve analysis revealed areas under the curve between 0.94 and 0.97. Interobserver agreement was higher for thin-slice (κ, 0.69-0.83) versus thick-slice nonenhanced CT reconstructions (κ, 0.38-0.45). CONCLUSIONS: Thin-slice reconstructions of standard cranial nonenhanced CT raw data allow for more sensitive and reliable detection of clots occluding the proximal middle cerebral artery.

The importance of size: successful recanalization by intravenous thrombolysis in acute anterior stroke depends on thrombus length.

BACKGROUND AND PURPOSE: We hypothesize that in acute middle cerebral artery stroke, thrombus lengths measured in thin-slice nonenhanced CT images define a limit beyond which systemic thrombolysis will fail to recanalize occluded arteries. METHODS: In 138 patients who presented with acute middle cerebral artery stroke and who were treated with intravenous thrombolysis (IVT), we measured lengths of thrombotic clots depicted as arterial hyperdensities in admission nonenhanced CT images with 2.5-mm slice width. Vascular recanalization was investigated after thrombolysis and recanalization results were related to thrombus lengths by logistic regression. RESULTS: In 62 patients, IVT resulted in recanalization; among these patients, no thrombus length exceeded 8 mm. The median modified Rankin scale score at hospital discharge was 2. In the remaining 76 patients, thrombus lengths mostly exceeded 8 mm and IVT failed in recanalization. These patients were discharged with a median modified Rankin scale score of 5. CONCLUSIONS: This study shows that in acute middle cerebral artery stroke, IVT has nearly no potential to recanalize occluded vessels if thrombus length exceeds 8 mm.

Assessment of thrombus in acute middle cerebral artery occlusion using thin-slice nonenhanced Computed Tomography reconstructions.

BACKGROUND AND PURPOSE: We sought to evaluate how accurately length and volume of thrombotic clots occluding cerebral arteries of patients with acute ischemic stroke can be assessed from nonenhanced CT (NECT) scans reconstructed with different slice widths. METHODS: NECT image data of 58 patients with acute ischemic stroke with vascular occlusion proven by CT angiography were reconstructed with slice widths of 1.25 mm, 2.5 mm, 3.75 mm, and 5 mm. Thrombus lengths and volumes were quantified based on these NECT images by detecting and segmenting intra-arterial hyperdensities. The results were compared with reference values of thrombus length and volume obtained from CT angiography images using Bland-Altman analysis and predefined levels or tolerance to find NECT slice thicknesses that allow for sufficiently accurate thrombus quantification. RESULTS: Thrombus length can be measured with high accuracy using the hyperdense middle cerebral artery sign detected in NECT images with slice thicknesses of 1.25 mm and 2.5 mm. We found mean deviations from the reference values and limits of agreement of -0.1 mm+/-0.6 mm with slice widths of 1.25 mm and 0.1 mm+/-0.7 mm for slice widths of 2.5 mm. Thrombus length measurements in NECT images with higher slice width and all evaluated thrombus volume measurements exhibited severe dependence on the level and did not match the accuracy criteria. CONCLUSIONS: The length of the hyperdense middle cerebral artery sign as detected on thin-slice NECT reconstructions in patients with acute ischemic stroke can be used to quantify thrombotic burden accurately. Thus, it might qualify as a new diagnostic parameter in acute stroke management that indicates and quantifies the extent of vascular obliteration.

Subacute stent thrombosis in intracranial stenting.

BACKGROUND AND PURPOSE: We sought to determine the safety of intracranial stenting with respect to subacute stent thrombosis in patients being treated with standardized antiplatelet therapy. METHODS: We retrospectively evaluated the outcome of primary intracranial stenting of atherosclerotic stenoses and of stenting in coil embolization procedures in 67 patients. We focused on those cases that led to subacute stent thrombosis even though the patients had been treated with standardized antiplatelet therapy before, during, and after stent placement. Patient age ranged from 19 to 78 years. In 33 patients, stents were placed for treatment of atherosclerotic stenoses; in the remaining 34 patients, stents were placed to assist coiling of aneurysms. The patients in this study were treated between January 2003 and August 2007. RESULTS: Of the total 67 patients initially treated successfully by intracranial stenting, 7 patients developed subacute stent thrombosis. Of these 7 patients, 3 received stent placement into the basilar artery because of an underlying stenosis; in 1 patient, a stenosis of the M1 segment of the middle cerebral artery was treated. In 3 patients, aneurysms of the anterior cerebral artery, the posterior inferior cerebellar artery, and the basilar artery were treated by stent-assisted coil embolization. In 4 of the 7 patients with subacute thrombosis, recanalization of stents by local application of recombinant tissue-type plasminogen activator was successful. CONCLUSIONS: Intracranial stenting can lead to subacute stent thrombosis, even in patients who are treated with standardized antiplatelet therapy. Such complications have been described for patients after coronary artery stenting, but to our knowledge, no one has reported on a comparable number of cases of intracranial stenting procedures. In certain clinical scenarios, local thrombolysis with recombinant tissue-type plasminogen activator is an important treatment option to deal with subacute stent thrombosis.