Patients Requiring Conversion to General Anesthesia during Endovascular Therapy Have Worse Outcomes: A Post Hoc Analysis of Data from the SAGA Collaboration.

BACKGROUND AND PURPOSE: Endovascular therapy for acute ischemic stroke is often performed with the patient under conscious sedation. Emergent conversion from conscious sedation to general anesthesia is sometimes necessary. The aim of this study was to assess the functional outcome in converted patients compared with patients who remained in conscious sedation and to identify predictors associated with the risk of conversion. MATERIALS AND METHODS: Data from 368 patients, included in 3 trials randomizing between conscious sedation and general anesthesia before endovascular therapy (SIESTA, ANSTROKE, and GOLIATH) constituted the study cohort. Twenty-one (11%) of 185 patients randomized to conscious sedation were emergently converted to general anesthesia. RESULTS: Absence of hyperlipidemia seemed to be the strongest predictor of conversion to general anesthesia, albeit a weak predictor (area under curve = 0.62). Sex, hypertension, diabetes, smoking status, atrial fibrillation, blood pressure, size of the infarct, and level and side of the occlusion were not significantly associated with conversion to general anesthesia. Neither age (mean age, 71.3 ± 13.8 years for conscious sedation versus 71.6 ± 12.3 years for converters, P = .58) nor severity of stroke (mean NIHSS score, 17 ± 4 versus 18 ± 4, respectively, P = .27) were significantly different between converters and those who tolerated conscious sedation. The converters had significantly worse outcome with a common odds ratio of 2.67 (P = .015) for a shift toward a higher mRS score compared with the patients remaining in the conscious sedation group. CONCLUSIONS: Patients undergoing conversion had significantly worse outcome compared with patients remaining in conscious sedation. No factor was identified that predicted conversion from conscious sedation to general anesthesia.

Data-efficient deep learning of radiological image data for outcome prediction after endovascular treatment of patients with acute ischemic stroke.

Treatment selection is becoming increasingly more important in acute ischemic stroke patient care. Clinical variables and radiological image biomarkers (old age, pre-stroke mRS, NIHSS, occlusion location, ASPECTS, among others) have an important role in treatment selection and prognosis. Radiological biomarkers require expert annotation and are subject to inter-observer variability. Recently, Deep Learning has been introduced to reproduce these radiological image biomarkers. Instead of reproducing these biomarkers, in this work, we investigated Deep Learning techniques for building models to directly predict good reperfusion after endovascular treatment (EVT) and good functional outcome using CT angiography images. These models do not require image annotation and are fast to compute. We compare the Deep Learning models to Machine Learning models using traditional radiological image biomarkers. We explored Residual Neural Network (ResNet) architectures, adapted them with Structured Receptive Fields (RFNN) and auto-encoders (AE) for network weight initialization. We further included model visualization techniques to provide insight into the network's decision-making process. We applied the methods on the MR CLEAN Registry dataset with 1301 patients. The Deep Learning models outperformed the models using traditional radiological image biomarkers in three out of four cross-validation folds for functional outcome (average AUC of 0.71) and for all folds for reperfusion (average AUC of 0.65). Model visualization showed that the arteries were relevant features for functional outcome prediction. The best results were obtained for the ResNet models with RFNN. Auto-encoder initialization often improved the results. We concluded that, in our dataset, automated image analysis with Deep Learning methods outperforms radiological image biomarkers for stroke outcome prediction and has the potential to improve treatment selection.

Follow-up infarct volume as a mediator of endovascular treatment effect on functional outcome in ischaemic stroke.

OBJECTIVE: The putative mechanism for the favourable effect of endovascular treatment (EVT) on functional outcome after acute ischaemic stroke is preventing follow-up infarct volume (FIV) progression. We aimed to assess to what extent difference in FIV explains the effect of EVT on functional outcome in a randomised trial of EVT versus no EVT (MR CLEAN). METHODS: FIV was assessed on non-contrast CT scan 5-7 days after stroke. Functional outcome was the score on the modified Rankin Scale at 3 months. We tested the causal pathway from intervention, via FIV to functional outcome with a mediation model, using linear and ordinal regression, adjusted for relevant baseline covariates, including stroke severity. Explained effect was assessed by taking the ratio of the log odds ratios of treatment with and without adjustment for FIV. RESULTS: Of the 500 patients included in MR CLEAN, 60 died and four patients underwent hemicraniectomy before FIV was assessed, leaving 436 patients for analysis. Patients in the intervention group had better functional outcomes (adjusted common odds ratio (acOR) 2.30 (95% CI 1.62-3.26) than controls and smaller FIV (median 53 vs. 81 ml) (difference 28 ml; 95% CI 13-41). Smaller FIV was associated with better outcome (acOR per 10 ml 0.60, 95% CI 0.52-0.68). After adjustment for FIV the effect of intervention on functional outcome decreased but remained substantial (acOR 2.05, 95% CI 1.44-2.91). This implies that preventing FIV progression explains 14% (95% CI 0-34) of the beneficial effect of EVT on outcome. CONCLUSION: The effect of EVT on FIV explains only part of the treatment effect on functional outcome. KEY POINTS: • Endovascular treatment in acute ischaemic stroke patients prevents progression of follow-up infarct volume on non-contrast CT at 5-7 days. • Follow-up infarct volume was related to functional outcome, but only explained a modest part of the effect of intervention on functional outcome. • A large proportion of treatment effect on functional outcome remains unexplained, suggesting FIV alone cannot be used as an early surrogate imaging marker of functional outcome.

The influence of blood pressure management on neurological outcome in endovascular therapy for acute ischaemic stroke.

BACKGROUND: Observational studies have suggested that low blood pressure and blood pressure variability may partially explain adverse neurological outcome after endovascular therapy with general anaesthesia (GA) for acute ischaemic stroke. The aim of this study was to further examine whether blood pressure related parameters during endovascular therapy are associated with neurological outcome. METHODS: The GOLIATH trial randomised 128 patients to either GA or conscious sedation for endovascular therapy in acute ischaemic stroke. The primary outcome was 90 day modified Rankin Score. The haemodynamic protocol aimed at keeping the systolic blood pressure >140 mm Hg and mean blood pressure >70 mm Hg during the procedure. Blood pressure related parameters of interest included 20% reduction in mean blood pressure; mean blood pressure <70 mm Hg, <80 mm Hg, and <90 mm Hg, respectively; time with systolic blood pressure <140 mm Hg; procedural minimum and maximum mean and systolic blood pressure; mean blood pressure at the time of groin puncture; postreperfusion mean blood pressure; blood pressure variability; and use of vasopressors. Sensitivity analyses were performed in the subgroup of reperfused patients. RESULTS: Procedural average mean and systolic blood pressures were higher in the conscious sedation group (P<0.001). The number of patients with mean blood pressure <70-90 mm Hg and systolic blood pressure <140 mm Hg, blood pressure variability, and use of vasopressors were all higher in the GA group (P<0.001). There was no statistically significant association between any of the examined blood pressure related parameters and the modified Rankin Score in the overall patient population, and in the subgroup of patients with full reperfusion. CONCLUSION: We found no statistically significant association between blood pressure related parameters during endovascular therapy and neurological outcome. CLINICAL TRIAL REGISTRATION: NCT 02317237.

Value of Thrombus CT Characteristics in Patients with Acute Ischemic Stroke.

BACKGROUND AND PURPOSE: Thrombus CT characteristics might be useful for patient selection for intra-arterial treatment. Our objective was to study the association of thrombus CT characteristics with outcome and treatment effect in patients with acute ischemic stroke. MATERIALS AND METHODS: We included 199 patients for whom thin-section NCCT and CTA within 30 minutes from each other were available in the Multicenter Randomized Clinical Trial of Endovascular Treatment for Acute ischemic stroke in the Netherlands (MR CLEAN) study. We assessed the following thrombus characteristics: location, distance from ICA terminus to thrombus, length, volume, absolute and relative density on NCCT, and perviousness. Associations of thrombus characteristics with outcome were estimated with univariable and multivariable ordinal logistic regression as an OR for a shift toward better outcome on the mRS. Interaction terms were used to investigate treatment-effect modification by thrombus characteristics. RESULTS: In univariate analysis, only the distance from the ICA terminus to the thrombus, length of >8 mm, and perviousness were associated with functional outcome. Relative thrombus density on CTA was independently associated with functional outcome with an adjusted common OR of 1.21 per 10% (95% CI, 1.02-1.43; P = .029). There was no treatment-effect modification by any of the thrombus CT characteristics. CONCLUSIONS: In our study on patients with large-vessel occlusion of the anterior circulation, CT thrombus characteristics appear useful for predicting functional outcome. However, in our study cohort, the effect of intra-arterial treatment was independent of the thrombus CT characteristics. Therefore, no arguments were provided to select patients for intra-arterial treatment using thrombus CT characteristics.

Topographic distribution of cerebral infarct probability in patients with acute ischemic stroke: mapping of intra-arterial treatment effect.

BACKGROUND: Since proof emerged that IA treatment (IAT) is beneficial for patients with acute ischemic stroke, it has become the standard method of care. Despite these positive results, recovery to functional independence is established in only about one-third of treated patients. The effect of IAT is commonly assessed by functional outcome, whereas its effect on brain tissue salvage is considered a secondary outcome measure (at most). Because patient and treatment selection needs to be improved, understanding the treatment effect on brain tissue salvage is of utmost importance. OBJECTIVE: To introduce infarct probability maps to estimate the location and extent of tissue damage based on patient baseline characteristics and treatment type. METHODS: Cerebral infarct probability maps were created by combining automatically segmented infarct distributions using follow-up CT images of 281 patients from the MR CLEAN trial. Comparison of infarct probability maps allows visualization and quantification of probable treatment effects. Treatment impact was calculated for 10 Alberta Stroke Program Early CT Score (ASPECTS) and 27 anatomical regions. RESULTS: The insular cortex had the highest infarct probability in both control and IAT populations (47.2% and 42.6%, respectively). Comparison showed significant lower infarct probability in 4 ASPECTS and 17 anatomical regions in favor of IAT. Most salvaged tissue was found within the ASPECTS M2 region, which was 8.5% less likely to infarct. CONCLUSIONS: Probability maps intuitively visualize the topographic distribution of infarct probability due to treatment, which makes it a promising tool for estimating the effect of treatment.

Comparison of CTA- and DSA-Based Collateral Flow Assessment in Patients with Anterior Circulation Stroke.

BACKGROUND AND PURPOSE: Collateral flow is associated with clinical outcome after acute ischemic stroke and may serve as a parameter for patient selection for intra-arterial therapy. In clinical trials, DSA and CTA are 2 imaging modalities commonly used to assess collateral flow. We aimed to determine the agreement between collateral flow assessment on CTA and DSA and their respective associations with clinical outcome. MATERIALS AND METHODS: Patients randomized in MR CLEAN with middle cerebral artery occlusion and both baseline CTA images and complete DSA runs were included. Collateral flow on CTA and DSA was graded 0 (absent) to 3 (good). Quadratic weighted κ statistics determined agreement between both methods. The association of both modalities with mRS at 90 days was assessed. Also, association between the dichotomized collateral score and mRS 0-2 (functional independence) was ascertained. RESULTS: Of 45 patients with evaluable imaging data, collateral flow was graded on CTA as 0, 1, 2, 3 for 3, 10, 20, and 12 patients, respectively, and on DSA for 12, 17, 10, and 6 patients, respectively. The κ-value was 0.24 (95% CI, 0.16-0.32). The overall proportion of agreement was 24% (95% CI, 0.12-0.38). The adjusted odds ratio for favorable outcome on mRS was 2.27 and 1.29 for CTA and DSA, respectively. The relationship between the dichotomized collateral score and mRS 0-2 was significant for CTA (P = .01), but not for DSA (P = .77). CONCLUSIONS: Commonly applied collateral flow assessment on CTA and DSA showed large differences, indicating that these techniques are not interchangeable. CTA was significantly associated with mRS at 90 days, whereas DSA was not.

Cerebral Angiography for Evaluation of Patients with CT Angiogram-Negative Subarachnoid Hemorrhage: An 11-Year Experience.

BACKGROUND AND PURPOSE: CT angiography is increasingly used to evaluate patients with nontraumatic subarachnoid hemorrhage given its high sensitivity for aneurysms. We investigated the yield of digital subtraction angiography among patients with SAH or intraventricular hemorrhage and a negative CTA. MATERIALS AND METHODS: An 11-year, single-center retrospective review of all consecutive patients with CTA-negative SAH was performed. Noncontrast head CT, CTA, DSA, and MR imaging studies were reviewed by 2 experienced interventional neuroradiologists and 1 neuroradiologist. RESULTS: Two hundred thirty patients (mean age, 54 years; 51% male) with CTA-negative SAH were identified. The pattern of SAH was diffuse (40%), perimesencephalic (31%), sulcal (31%), isolated IVH (6%), or identified by xanthochromia (7%). Initial DSA yield was 13%, including vasculitis/vasculopathy (7%), aneurysm (5%), arteriovenous malformation (0.5%), and dural arteriovenous fistula (0.5%). An additional 6 aneurysms/pseudoaneurysms (4%) were identified by follow-up DSA, and a single cavernous malformation (0.4%) was identified by MRI. No cause of hemorrhage was identified in any patient presenting with isolated intraventricular hemorrhage or xanthochromia. Diffuse SAH was due to aneurysm rupture (17%); perimesencephalic SAH was due to aneurysm rupture (3%) or vasculitis/vasculopathy (1.5%); and sulcal SAH was due to vasculitis/vasculopathy (32%), arteriovenous malformation (3%), or dural arteriovenous fistula (3%). CONCLUSIONS: DSA identifies vascular pathology in 13% of patients with CTA-negative SAH. Aneurysms or pseudoaneurysms are identified in an additional 4% of patients by repeat DSA following an initially negative DSA. All patients with CT-negative SAH should be considered for DSA. The pattern of SAH may suggest the cause of hemorrhage, and aneurysms should specifically be sought with diffuse or perimesencephalic SAH.

Multimodal Diagnostic Imaging for Hyperacute Stroke.

In April 2015, the American Roentgen Ray Society and the American Society of Neuroradiology cosponsored a unique program designed to evaluate the state of the art in the imaging work-up of acute stroke. This topic has grown in importance because of the recent randomized controlled trials demonstrating the clear efficacy of endovascular stroke treatment. The authors, who were participants in that symposium, will highlight the points of emphasis in this article.

Application of a Novel Brain Arteriovenous Malformation Endovascular Grading Scale for Transarterial Embolization.

BACKGROUND AND PURPOSE: The advent of modern neuroendovascular techniques has highlighted the need for a simple, effective, and reliable brain arteriovenous malformation endovascular grading scale. A novel scale of this type has recently been described. It incorporates the number of feeding arteries, eloquence, and the presence of an arteriovenous fistula component. Our aim is to assess the validity of this grading scale. MATERIALS AND METHODS: We retrospectively reviewed all suspected brain arteriovenous malformations at Massachusetts General Hospital from 2005 to 2013, identifying 126 patients who met the inclusion criteria. Spearman correlations between endovascular and Spetzler-Martin grading scales and long-term outcomes were performed. Median endovascular grades were compared between treatment modalities and endovascular outcomes. Binary regression analysis was performed with major endovascular complications as a dichotomized dependent variable. Intraclass correlation coefficients were calculated for interobserver reliability of the endovascular grading scale. RESULTS: A significant Spearman correlation between the endovascular grade and the Spetzler-Martin grade was demonstrated (ρ = 0.5, P < .01). Differences in the median endovascular grades between the endovascular cure (median = 2) and endovascular complication groups (median = 4) (P < .05) and between the endovascular cure and successful multimodal treatment groups (median = 3) (P < .05) were demonstrated. The endovascular grade was the only independent predictor of complications (OR = 0.5, P < .01). The intraclass correlation coefficient of the endovascular grade was 0.71 (P < .01). CONCLUSIONS: Validation of a brain arteriovenous malformation endovascular grading scale demonstrated that endovascular grades of ≤II were associated with endovascular cure, while endovascular grades of ≤III were associated with multimodal cure or significant lesion reduction and favorable outcome. The endovascular grade provides useful information to refine risk stratification for endovascular and multimodal treatment.

Combining MRI with NIHSS thresholds to predict outcome in acute ischemic stroke: value for patient selection.

BACKGROUND AND PURPOSE: Selecting acute ischemic stroke patients for reperfusion therapy on the basis of a diffusion-perfusion mismatch has not been uniformly proved to predict a beneficial treatment response. In a prior study, we have shown that combining clinical with MR imaging thresholds can predict clinical outcome with high positive predictive value. In this study, we sought to validate this predictive model in a larger patient cohort and evaluate the effects of reperfusion therapy and stroke side. MATERIALS AND METHODS: One hundred twenty-three consecutive patients with anterior circulation acute ischemic stroke underwent MR imaging within 6 hours of stroke onset. DWI and PWI volumes were measured. Lesion volume and NIHSS score thresholds were used in models predicting good 3-month clinical outcome (mRS 0-2). Patients were stratified by treatment and stroke side. RESULTS: Receiver operating characteristic analysis demonstrated 95.6% and 100% specificity for DWI > 70 mL and NIHSS score > 20 to predict poor outcome, and 92.7% and 91.3% specificity for PWI (mean transit time) < 50 mL and NIHSS score < 8 to predict good outcome. Combining clinical and imaging thresholds led to an 88.8% (71/80) positive predictive value with a 65.0% (80/123) prognostic yield. One hundred percent specific thresholds for DWI (103 versus 31 mL) and NIHSS score (20 versus 17) to predict poor outcome were significantly higher in treated (intravenous and/or intra-arterial) versus untreated patients. Prognostic yield was lower in right- versus left-sided strokes for all thresholds (10.4%-20.7% versus 16.9%-40.0%). Patients with right-sided strokes had higher 100% specific DWI (103.1 versus 74.8 mL) thresholds for poor outcome, and the positive predictive value was lower. CONCLUSIONS: Our predictive model is validated in a much larger patient cohort. Outcome may be predicted in up to two-thirds of patients, and thresholds are affected by stroke side and reperfusion therapy.

Safety and effectiveness of sacroplasty: a large single-center experience.

BACKGROUND AND PURPOSE: Sacral insufficiency fractures are a common cause of severe low back pain and immobilization in patients with osteoporosis or cancer. Current practice guideline recommendations range from analgesia and physical therapy to resection with surgical fixation. We sought to assess the safety and effectiveness of sacroplasty, an emerging minimally invasive treatment. MATERIALS AND METHODS: We performed a retrospective review of institutional databases for percutaneous sacroplasty performed between January 2004 and September 2013. Demographic and procedural data and pre- and posttreatment Visual Analog Scale, Functional Mobility Scale, and Analgesic Scale scores were reviewed. Overall response was rated by using a 4-point scale (1, complete resolution of pain; 2, improvement of pain; 3, no change; 4, worsened pain) assessed at short-term follow-up. RESULTS: Fifty-three patients were included; most (83%) were female. Fracture etiology was cancer-related (55%), osteoporotic insufficiency (30%), and minor trauma (15%). No major complication or procedure-related morbidity occurred. There were statistically significant decreases in the Visual Analog Scale (P < .001), Functional Mobility Scale (P < .001), and Analgesic Scale scores (P < .01) in 27 patients with recorded data: pretreatment Visual Analog Scale (median [interquartile range], 9.0 [8.0-10.0]); Functional Mobility Scale, 3.0 (2.0-3.0); and Analgesic Scale scores, 3.0 (3.0-4.0) were reduced to 3.0 (0.0-5.8), 1.0 (0.25-2.8), and 3.0 (2.0-3.8) posttreatment. When we used the overall 4-point score at a mean of 27 days, 93% (n = 45) reported complete resolution or improvement in overall pain. CONCLUSIONS: In this single-center cohort, sacroplasty was a safe and effective procedure. There were significant short-term gains in pain relief, increased mobility, and decreased dependence on pain medication.

Transarterial onyx embolization of cranial dural arteriovenous fistulas: long-term follow-up.

BACKGROUND AND PURPOSE: Endovascular therapy with liquid embolic agents is a common treatment strategy for cranial dural arteriovenous fistulas. This study evaluated the long-term effectiveness of transarterial Onyx as the single embolic agent for curative embolization of noncavernous cranial dural arteriovenous fistulas. MATERIALS AND METHODS: We performed a retrospective review of 40 consecutive patients with 41 cranial dural arteriovenous fistulas treated between March 2006 and June 2012 by using transarterial Onyx embolization with intent to cure. The mean age was 57 years; one-third presented with intracranial hemorrhage. Most (85%) had cortical venous drainage. Once angiographic cure was achieved, long-term treatment effectiveness was assessed with DSA and clinical follow-up. RESULTS: Forty-nine embolization sessions were performed; 85% of cranial dural arteriovenous fistulas were treated in a single session. The immediate angiographic cure rate was 95%. The permanent neurologic complication rate was 2% (mild facial palsy). Thirty-five of the 38 patients with initial cure underwent short-term follow-up DSA (median, 4 months). The short-term recurrence rate was only 6% (2/35). All patients with occlusion at short-term DSA undergoing long-term DSA (median, 28 months) had durable occlusion. No patient with long-term clinical follow-up (total, 117 patient-years; median, 45 months) experienced hemorrhage. CONCLUSIONS: Transarterial embolization with Onyx as the single embolic agent results in durable long-term cure of noncavernous cranial dural arteriovenous fistulas. Recurrence rates are low on short-term follow-up, and all patients with angiographic occlusion on short-term DSA follow-up have experienced a durable long-term cure. Thus, angiographic cure should be defined at short-term follow-up angiography instead of at the end of the final embolization session. Finally, long-term DSA follow-up may not be necessary if occlusion is demonstrated on short-term angiographic follow-up.

Temporal evolution of intraparenchymal hyperdensity after intra-arterial therapy in patients with ischemic stroke: optimal discrimination between hemorrhage and iodinated contrast.

PURPOSE: CT hyperattenuation arising from iodinated contrast has a different temporal evolution than that arising due to hemorrhage. This paper presents a method for optimal discrimination between hemorrhage and iodinated contrast in a postintervention CT in stroke patients. METHODS: We analyzed the brain computed tomography (CT) scans of consecutive patients with intraparenchymal hyperattenuation due to hemorrhage (n=41), those due to iodinated contrast alone (n=24), and those due to contrast mixed with hemorrhage after reperfusion therapy (n=14) in stroke patients. The difference between the maximum enhancement in hyperattenuation in the affected area and the corresponding contralateral area, dubbed Relative Maximum Enhancement (RME), was tracked over time. We fitted regression models to the RME changes due to hemorrhage and contrast to describe their temporal decay, and then derived the optimal discriminant curve that distinguishes the two. A computer algorithm coregistered the baseline and follow-up CT scans and performed pixel-by-pixel comparison to determine hemorrhage and iodinated contrast based on the RME changes with respect to the discriminant curve. RESULTS: For both hemorrhage (k= -0.004, R (2) =0.7) and iodinated contrast (k= -0.064, R (2) =0.9), the temporal evolution of RMEs were best fitted by exponential decay curves, with respective half-lives of 192.3 and 10.7 h. An exponential decay model (k= -0.026) for optimal discrimination of hemorrhage vs. contrast was fitted. The computer algorithm implementing this model was successful in predicting the presence of hemorrhage in a hyperdense lesion with sensitivity =93% and specificity =91%. CONCLUSION: Intraparenchymal hemorrhage and contrast have markedly different decay half-lives that can be used to assess hemorrhage in a hyperdense lesion on a CT scan after intra-arterial therapy.

Malignant CTA collateral profile is highly specific for large admission DWI infarct core and poor outcome in acute stroke.

BACKGROUND AND PURPOSE: Large admission DWI lesion volumes are associated with poor outcomes despite acute stroke treatment. The primary aims of our study were to determine whether CTA collaterals correlate with admission DWI lesion volumes in patients with AIS with proximal occlusions, and whether a CTA collateral profile could identify large DWI volumes with high specificity. MATERIALS AND METHODS: We studied 197 patients with AIS with M1 and/or intracranial ICA occlusions. We segmented admission and follow-up DWI lesion volumes, and categorized CTA collaterals by using a 5-point CS system. ROC analysis was used to determine CS accuracy in predicting DWI lesion volumes >100 mL. Patients were dichotomized into 2 categories: CS = 0 (malignant profile) or CS>0. Univariate and multivariate analyses were performed to compare imaging and clinical variables between these 2 groups. RESULTS: There was a negative correlation between CS and admission DWI lesion volume (ρ = -0.54, P < .0001). ROC analysis revealed that CTA CS was a good discriminator of DWI lesion volume >100 mL (AUC = 0.84, P < .001). CS = 0 had 97.6% specificity and 54.5% sensitivity for DWI volume >100 mL. CS = 0 patients had larger mean admission DWI volumes (165.8 mL versus 32.7 mL, P < .001), higher median NIHSS scores (21 versus 15, P < .001), and were more likely to become functionally dependent at 3 months (95.5% versus 64.0%, P = .003). Admission NIHSS score was the only independent predictor of a malignant CS (P = .007). CONCLUSIONS: In patients with AIS with PAOs, CTA collaterals correlate with admission DWI infarct size. A malignant collateral profile is highly specific for large admission DWI lesion size and poor functional outcome.

Interobserver reliability of baseline noncontrast CT Alberta Stroke Program Early CT Score for intra-arterial stroke treatment selection.

BACKGROUND AND PURPOSE: Early ischemic changes on pretreatment NCCT quantified using ASPECTS have been demonstrated to predict outcomes after IAT. We sought to determine the interobserver reliability of ASPECTS for patients with AIS with PAO and to determine whether pretreatment ASPECTS dichotomized at 7 would demonstrate at least substantial κ agreement. MATERIALS AND METHODS: From our prospective IAT data base, we identified consecutive patients with anterior circulation PAO who underwent IAT over a 6-year period. Only those with an evaluable pretreatment NCCT were included. ASPECTS was graded independently by 2 experienced readers. Interrater agreement was assessed for total ASPECTS, dichotomized ASPECTS (≤ 7 versus >7), and each ASPECTS region. Statistical analysis included determination of Cohen κ coefficients and concordance correlation coefficients. PABAK coefficients were also calculated. RESULTS: One hundred fifty-five patients met our study criteria. Median pretreatment ASPECTS was 8 (interquartile range 7-9). Interrater agreement for total ASPECTS was substantial (concordance correlation coefficient = 0.77). The mean ASPECTS difference between readers was 0.2 (95% confidence interval, -2.8 to 2.4). For dichotomized ASPECTS, there was a 76.8% (119/155) observed rate of agreement, with a moderate κ = 0.53 (PABAK = 0.54). By region, agreement was worst in the internal capsule and the cortical areas, ranging from fair to moderate. After adjusting for prevalence and bias, agreement improved to substantial or near perfect in most regions. CONCLUSIONS: Interobserver reliability is substantial for total ASPECTS but is only moderate for ASPECTS dichotomized at 7. This may limit the utility of dichotomized ASPECTS for IAT selection.

Differentiation of hemorrhage from iodinated contrast in different intracranial compartments using dual-energy head CT.

BACKGROUND AND PURPOSE: Identification of ICH, particularly after ischemic stroke therapy, is important for guiding subsequent antithrombotic management and is often confounded by contrast staining or extravasations within intracerebral or extra-axial compartments. This study evaluates the accuracy of DECT in distinguishing ICH from iodinated contrast in patients who received contrast via IA or IV delivery. MATERIALS AND METHODS: Forty patients who had received IA or IV contrast were evaluated using a DECT scanner at 80kV and 140kV to distinguish hyperdensities secondary to contrast staining or extravasation from those representing ICH. A 3-material decomposition algorithm was used to obtain virtual noncontrast images and iodine overlay images. Sensitivity, specificity, and accuracy of DECT in prospectively distinguishing intracranial contrast from hemorrhage within parenchymal, subarachnoid, extra-axial, intraventricular, and intra-arterial compartments were computed using routine clinical follow-up imaging as the standard of reference. RESULTS: A total of 148 foci of intracranial hyperattenuation were identified. Of these, 142 were correctly classified for the presence of hemorrhage by DECT. The sensitivity, specificity, and accuracy for identifying hemorrhage, depending on the compartment being considered, were 100%, 84.4%-100%, and 87.2%-100%, respectively. The only instances where DECT failed to correctly identify the source of hyperattenuation was in the presence of diffuse parenchymal calcification (n = 5) and a metallic streak artifact (n = 1). CONCLUSION: After IA and/or IV contrast administration, DECT can accurately differentiate all types of ICH from iodinated contrast without employing any additional radiation.

Cerebral blood flow thresholds for tissue infarction in patients with acute ischemic stroke treated with intra-arterial revascularization therapy depend on timing of reperfusion.

BACKGROUND AND PURPOSE: MR perfusion CBF values can distinguish hypoperfused penumbral tissue likely to infarct from that which is likely to recover. Our aim was to determine if CBF thresholds for tissue infarction depend on the timing of recanalization in patients with acute stroke treated with IAT. MATERIALS AND METHODS: Twenty-six patients with acute proximal anterior circulation strokes underwent DWI and PWI before IAT. rCBF was obtained in the following areas: 1) C with abnormal DWI, reduced CBF, follow-up infarction; 2) PI with normal DWI, reduced CBF, follow-up infarction and 3) PNI with normal DWI, reduced CBF, normal follow-up. rCBF in tissue reperfused at <6 hours (early recanalizers), in tissue reperfused at >6 hours (late RC), and in NRC was compared. RESULTS: For C, mean rCBF was 0.13 (SEM, 0.002), 0.29 (0.007), and 0.21 (0.004) for early recanalizers, late recanalizers, and nonrecanalizers, respectively (P < .001, for all comparisons). For PI, mean rCBF was 0.34 (0.006), 0.38 (0.008), and 0.39 (0.005) for early recanalizers, late recanalizers, and nonrecanalizers, respectively (P < .001 for early-versus-late recanalizers and versus nonrecanalizers; P > .05 for late recanalizers versus nonrecanalizers). For PNI, the mean rCBF was 0.38 (0.002), 0.48 (0.003), and 0.48 (0.004) for early recanalizers, late recanalizers, and nonrecanalizers, respectively (P < .001 for early-versus-late recanalizers and nonrecanalizers; P > .05 for late recanalizers versus nonrecanalizers). ROC analyzis demonstrated optimal rCBF thresholds for tissue infarction of 0.27 (sensitivity, 80%; specificity, 87%), 0.44 (sensitivity, 77%; specificity, 75%), and 0.41 (sensitivity, 78%; specificity, 77%) for early recanalizers, late recanalizers, and nonrecanalizers, respectively. CONCLUSIONS: CBF thresholds for tissue infarction in patients with acute stroke are lower in tissue that is reperfused at earlier time points. This information may be important in selecting patients who might benefit from reperfusion therapy.