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Background and Purpose: Distal medium vessel occlusions (DMVOs) are a significant contributor to acute ischemic stroke (AIS), with collateral status (CS) playing a pivotal role in modulating ischemic damage progression. We aimed to explore baseline characteristics associated with CS in AIS-DMVO., Methods: This retrospective analysis of a prospectively collected database enrolled 130 AIS-DMVO patients from two comprehensive stroke centers. Baseline characteristics, including patient demographics, admission National Institutes of Health Stroke Scale (NIHSS) score, admission Los Angeles Motor Scale (LAMS) score, and co-morbidities, including hypertension, hyperlipidemia, diabetes, coronary artery disease, atrial fibrillation, and history of transient ischemic attack or stroke, were collected. The analysis was dichotomized to good CS, reflected by hypoperfusion index ratio (HIR) <.3, versus poor CS, reflected by HIR ≥.3., Results: Good CS was observed in 34% of the patients. As to the occluded location, 43.8% occurred in proximal M2, 16.9% in mid M2, 35.4% in more distal middle cerebral artery, and 3.8% in distal anterior cerebral artery. In multivariate logistic analysis, a lower NIHSS score and a lower LAMS score were both independently associated with a good CS (odds ratio [OR]: 0.88, 95% confidence interval [CI]: 0.82-0.95, p < .001 and OR: 0.77, 95% CI: 0.62-0.96, p = .018, respectively). Patients with poor CS were more likely to manifest as moderate to severe stroke (29.1% vs. 4.5%, p < .001), while patients with good CS had a significantly higher chance of having a minor stroke clinically (40.9% vs. 12.8%, p < .001)., Conclusions: CS remains an important determinant in the severity of AIS-DMVO. Collateral enhancement strategies may be a worthwhile pursuit in AIS-DMVO patients with more severe initial stroke presentation, which can be swiftly identified by the concise LAMS and serves as a proxy for underlying poor CS., (© 2024 American Society of Neuroimaging.)

Background and Purpose: Transcranial Doppler (TCD) identifies acute stroke patients with arterial occlusion where treatment may not effectively open the blocked vessel. This study aimed to examine the clinical utility and prognostic value of TCD flow findings in patients enrolled in a multicenter prospective study (CLOTBUST-PRO)., Methods: Patients enrolled with intracranial occlusion on computed tomography angiography (CTA) who underwent urgent TCD evaluation before intravenous thrombolysis was included in this analysis. TCD findings were assessed using the mean flow velocity (MFV) ratio, comparing the reciprocal ratios of the middle cerebral artery (MCA) depths bilaterally (affected MCA-to-contralateral MCA MFV [aMCA/cMCA MFV ratio])., Results: A total of 222 patients with intracranial occlusion on CTA were included in the study (mean age: 64 ± 14 years, 62% men). Eighty-eight patients had M1 MCA occlusions; baseline mean National Institutes of Health Stroke Scale (NIHSS) score was 16, and a 24-hour mean NIHSS score was 10 points. An aMCA/cMCA MFV ratio of <.6 had a sensitivity of 99%, specificity of 16%, positive predictive value (PV) of 60%, and negative PV of 94% for identifying large vessel occlusion (LVO) including M1 MCA, terminal internal carotid artery, or tandem ICA/MCA. Thrombolysis in Brain Ischemia scale, with (grade ≥1) compared to without flow (grade 0), showed a sensitivity of 17.1%, specificity of 86.9%, positive PV of 62%, and negative PV of 46% for identifying LVO., Conclusions: TCD is a valuable modality for evaluating arterial circulation in acute ischemic stroke patients, demonstrating significant potential as a screening tool for intravenous/intra-arterial lysis protocols., (© 2024 The Author(s). Journal of Neuroimaging published by Wiley Periodicals LLC on behalf of American Society of Neuroimaging.)

Background and Purpose: The Alberta Stroke Program Early CT Score (ASPECTS) is a widely used scoring system for evaluating ischemic stroke to determine therapeutic strategy. However, there is variation in the interobserver agreement of ASPECTS. This systematic review and meta-analysis aimed to investigate the interobserver agreement of total and regional ASPECTS., Methods: A comprehensive search was conducted in the Web of Sciences, PubMed, and Scopus databases to identify relevant studies. Inclusion criteria were studies of noncontrast CT performed within 24 hours of ischemic stroke in the middle cerebral artery territory., Results: A total of 20 studies, with 3482 patients, reporting interobserver agreement of total and regional ASPECTS were included in the meta-analysis. The interobserver agreement for total ASPECTS in studies using Kappa coefficient (κ) analysis was substantial (κ = .67, 95% confidence interval [CI]: .57-.78). In studies using intraclass correlation coefficient (ICC) analysis, agreement was excellent (ICC = .84, 95% CI: .77-.90). Interobserver agreement was higher in studies in which the observer was unblinded to clinical scenario in both groups (κ = .74, 95% CI: .59-.89, and ICC = .82, 95% CI: .79-.85). Per-region analysis showed that the caudate nucleus had the highest agreement (κ = .68, 95% CI: .60-.76, and ICC = .84, 95% CI: .74-.93), while M2 and internal capsule in Kappa studies (κ = .45, 95% CI: .34-.55 and κ = .47, 95% CI: .28-.66), and M4 and internal capsule in ICC studies (ICC = .54, 95% CI: .43-.64 and ICC = .55, 95% CI: .18-.91) had the lowest agreement., Conclusion: This meta-analysis demonstrates substantial to excellent interobserver agreement for total ASPECTS, which supports using this method for stroke treatment. However, findings emphasize the need to consider interobserver agreement in specific regions of ASPECTS for treatment decisions., (© 2024 American Society of Neuroimaging.)

Background and Purpose: To compare the accuracy of subjective Alberta Stroke Program Early CT Score (sASPECTS) evaluation and that of an automated prototype software (aASPECTS) on nonenhanced CT (NECT) in patients with early anterior territory stroke and controls using side-to-side quantification of hypoattenuated brain areas., Methods: We retrospectively analyzed the NECT scans of 42 consecutive patients with ischemic stroke before reperfusion and 42 controls using first sASPECTS and subsequently aASPECTS. We assessed the differences in Alberta Stroke Program Early CT Score (ASPECTS) and calculated the sensitivity and specificity of NECT with CT perfusion, whereas cerebral blood volume (CBV) served as the reference standard for brain infarction., Results: The clot was located in the middle cerebral artery (MCA) in 47.6% of cases and the internal carotid artery (ICA) in 28.6% of cases. Ten cases presented combined ICA and MCA occlusions. The stroke was right sided in 52.4% of cases and left sided in 47.6%. Reader-based NECT analysis yielded a median sASPECTS of 10. The median CBV-based ASPECTS was 7. Compared to the area of decreased CBV, sASPECTS yielded a sensitivity of 12.5% and specificity of 86.8%. The software prototype (aASPECTS) yielded an overall sensitivity of 65.5% and a specificity of 92.2%. The interreader agreement for ASPECTS evaluation of admission NECT and follow-up CT was almost perfect (κ = .93). The interreader agreement of the CBV color map evaluation was substantial (κ = .77)., Conclusions: aASPECTS of NECT can outperform sASPECTS for stroke detection., (© 2023 The Authors. Journal of Neuroimaging published by Wiley Periodicals LLC on behalf of American Society of Neuroimaging.)

Background and Purpose: Hemorrhagic transformation (HT) has been reported in up to 50% of acute ischemic stroke (AIS) patients with a large vessel occlusion (LVO) treated with endovascular thrombectomy (EVT). HT may be driven by postrecanalization hyperperfusion injury and is independently associated with worse functional outcomes. Strategies to identify patients at risk for HT may assist in developing preventive therapies., Methods: We prospectively included adult AIS patients with an anterior circulation LVO achieving successful recanalization after EVT. Consenting participants received transcranial Doppler ultrasound (TCD) within 18 hours of procedure completion. We compared flow velocities according to the presence of HT on the computed tomography scan performed within the first 24±12 hours from the end of EVT. We also evaluated the association of flow velocities with systemic blood pressure (BP) readings at the time of insonation., Results: A total of 48 patients consented to participate in the study. Six (12%) were excluded due to the absence of temporal windows. HT was detected in 20 participants (48%). Those with HT had higher peak systolic velocities on the middle cerebral arteries compared to those without HT for both the symptomatic (107±42 vs. 82±25 cm/second, p = .024) and asymptomatic (97±21 vs. 81±25 cm/second, p = .040) sides. No correlation of flow velocities on either the symptomatic or asymptomatic side and BP measurements at the time of insonation was detected., Conclusion: TCD can identify patients at risk of HT following successful EVT. TCD could serve as an inexpensive ancillary test to guide participant selection for clinical trials targeting postprocedural reperfusion injury., (© 2023 The Authors. Journal of Neuroimaging published by Wiley Periodicals LLC on behalf of American Society of Neuroimaging.)

Background and Purpose: Predicting functional outcomes after endovascular thrombectomy (EVT) is of interest to patients and families as they navigate hospital and post-acute care decision-making. We evaluated the prognostic ability of several scales to predict good neurological function after EVT., Methods: We retrospectively analyzed records from a health system's code stroke registry, including consecutive successful thrombectomy patients from August 2020 to February 2023 presenting with an anterior circulation large vessel occlusion who were evaluated with pre-EVT CT perfusion. Primary and secondary outcomes were 90-day modified Rankin Scale (mRS) scores 0-2 and 0-1, respectively. Logistic regression was performed to evaluate the ability of each scale to predict the outcomes. Scales were compared by calculating the area under the curve (AUC)., Results: A total of 465 patients (mean age 68.1 [±14.9] years, median National Institutes of Health Stroke Scale [NIHSS] 16 [11-21]) met inclusion criteria. In the logistic regression, the Charlotte Large artery occlusion Endovascular therapy Outcome Score (CLEOS), Totaled Health Risks in Vascular Events, Houston Intra-Arterial Therapy-2, Pittsburgh Response to Endovascular therapy, and Stroke Prognostication using Age and NIHSS were significant in predicting the primary and secondary outcomes. CLEOS was superior to all other scales in predicting 90-day mRS 0-2 (AUC .75, 95% confidence interval [CI] .70-.80) and mRS 0-1 (AUC .74, 95% CI .69-.78). Twenty of 22 patients (90.9%) with CLEOS <315 had 90-day mRS 0-2., Conclusions: CLEOS predicts independent and excellent neurological function after anterior circulation EVT., (© 2023 American Society of Neuroimaging.)

Background and Purpose: This study was dedicated to investigating the agreement of the calculated results of two CT perfusion (CTP) postprocessing software packages, including parameter maps and ischemic volume, focusing on the infarct core volume (ICV) and penumbra volume (PV)., Methods: A retrospective collection of 235 patients with acute ischemic stroke who underwent CTP examination were enrolled. All images had been analyzed with two software pipelines, RAPID CTP and AccuCTP, and the comparative analysis was based on ICV and PV results calculated by both software packages. The agreement of parameter maps was evaluated by root mean square error and Bland-Altman analysis. The ICV and PV agreement was evaluated by intraclass correlation coefficient (ICC) and Bland-Altman analysis. The accuracy of ICV and PV based on multiple thresholds was also analyzed., Results: The ICV and PV of AccuCTP and RAPID CTP show excellent agreement. The relative differences of the parameter maps were all within 10% and the Bland-Altman analysis also showed a strong agreement. From ordinary least squares fitting results, both ICV and PV had a remarkably high goodness of fit (ICV, R 2 = 0.975 [p<.001]; PV, R 2 = 0.964 [p<.001]). For the ICC analysis, both had high ICC scores (ICV ICC 0.984, 95% CI [confidence interval] 0.973-0.989; PV ICC 0.955, 95% CI 0.947-0.964). Furthermore, multi-threshold analysis on the basis of ICV and PV also achieved reliable analytical accuracy., Conclusions: The image analysis results of AccuCTP are in excellent agreement with RAPID CTP and can be used as an alternative analysis tool to RAPID CTP software in stroke clinical practice., (© 2023 American Society of Neuroimaging.)

Background and Purpose: Malignant cerebral edema (MCE) secondary to ischemic stroke is a highly morbid condition. Decompressive craniectomy (DC) is the only treatment for MCE that has been shown to reduce mortality. We examined whether early infarction and/or hypoperfusion in specific topographic regions was predictive of the need for later DC., Methods: A retrospective database of patients evaluated for large vessel occlusion (LVO) stroke at Stanford between 2010 and 2019 was used. Thirty patients with LVO and baseline perfusion MRI who underwent DC were evaluated. Propensity matching based on age, lesion size, and recanalization status was performed on the remaining cohort. Baseline masks of apparent diffusion coefficient (ADC) + T max  >6 seconds lesions were generated using automated perfusion software. Voxel-based lesion symptom maping was used to perform logistic regression at each voxel to generate statistical maps of lesion location associated with DC. Hemispheres were combined to increase statistical power., Results: Sixty patients were analyzed. After adjusting for age, lesion size, and recanalization status as covariates, scattered cortical regions, predominately within the temporal and frontal lobe, were mildly to moderately predictive of the need for DC (z-scores: 2.4-6.74, p < .01)., Conclusions: Scattered temporal and frontal lobe regions on baseline diffusion and perfusion MRI were found to be mildly to moderately predictive of the need for subsequent DC in patients with LVO stroke., (© 2023 American Society of Neuroimaging.)

Background and Purpose: The relationship between ischemic stroke site and occurrence of poststroke epilepsy (PSE) is incompletely understood. This study intended to evaluate incidence and temporal profiles of seizures and to correlate ischemic lesion sites with PSE using voxel-based lesion symptom mapping (VLSM)., Methods: Patients with imaging-confirmed first-ever ischemic stroke without prior history of epilepsy were prospectively included. Demographic data, cardiovascular risk factors, and National Institute of Health Stroke Scale (NIHSS) scores were assessed. Data on seizures and modified Rankin scale scores were determined within a 90-day period after stroke onset. Ischemic lesion sites were correlated voxel wise with occurrence of PSE using nonparametric permutation test. Age- and sex-matched patients with first-ever ischemic strokes without PSE after 90 days served as controls for the VLSM analysis., Results: The stroke database contained 809 patients (mean age: 68.4 ± 14.2 years) with first-ever imaging-confirmed ischemic strokes without history of epilep. Incidence of PSE after 90-day follow-up was 2.8%. Five additional patients were admitted to the emergency department with a seizure after 90-day follow-up. Fifty percent of the seizures occurred in the acute phase after stroke. PSE patients had higher NIHSS scores and infarct volumes compared to controls without PSE (p < .05). PSE patients had infarcts predominantly involving the cerebral cortex. The hemisphere-specific VLSM analysis shows associations between PSE and damaged voxels in the left-hemispheric temporo-occipital transition zone., Conclusions: The data indicate that PSE occurs in a small proportion of patients with rather large ischemic strokes predominantly involving the cerebral cortex. Especially patients with ischemic lesions in the temporo-occipital cortex are vulnerable to develop PSE., (© 2023 The Authors. Journal of Neuroimaging published by Wiley Periodicals LLC on behalf of American Society of Neuroimaging.)

Background and Purpose: There are limited data regarding safety and effectiveness of concurrent intraarterial thrombolytics as adjunct to mechanical thrombectomy in acute ischemic stroke patients with basilar artery occlusion., Methods: We analyzed data from a prospective multicenter registry to assess the independent effect of intraarterial thrombolysis on (1) favorable outcome (modified Rankin Scale 0-3) at 90 days; (2) symptomatic intracranial hemorrhage (sICH) within 72 hours; and (3) death within 90 days post-enrollment after adjustment for potential confounders., Results: There was no difference in the adjusted odds of achieving favorable outcome at 90 days (odds ratio [OR] = 1.1, 95% confidence interval [CI]: 0.73-1.68) in patients who received intraarterial thrombolysis (n = 126) compared with those who did not receive intraarterial thrombolysis (n = 1546) despite significantly higher use in patients with postprocedure modified Thrombolysis in Cerebral Infarction (mTICI) grade <3. There were no differences in adjusted odds of sICH within 72 hours (OR = 0.8, 95% CI: 0.31-2.08) or death within 90 days (OR = 0.91, 95% CI: 0.60-1.37). In subgroup analyses, intraarterial thrombolysis was associated with (nonsignificantly) higher odds of achieving a favorable outcome at 90 days among patients aged between 65 and 80 years, those with National Institutes of Health Stroke Scale score <10, and those with postprocedure mTICI grade 2b., Conclusions: Our analysis supported the safety of intraarterial thrombolysis as adjunct to mechanical thrombectomy in acute ischemic stroke patients with basilar artery occlusion. Identification of patient subgroups in whom intraarterial thrombolytics appeared to be more beneficial may assist in future clinical trial designs., (© 2023 American Society of Neuroimaging.)

Background and Purpose: Precise evaluation of brain computerized tomography (CT) is a crucial step in acute ischemic stroke evaluation. Electronic Alberta Stroke Program Early CT Score (E-ASPECTS) helps in the selection of patients who may be eligible for thrombolysis. This paper seeks to assess the performance of emergency physicians (EPs) in the evaluation of ASPECTS scores with and without the use of E-ASPECTS and to compare their results with neuroradiologists., Methods: A total of 116 patients were selected. Initially, two EPs and two neuroradiologists evaluated the admission nonenhanced CT without E-ASPECTS. Then, after 30 days, they re-evaluated the images using E-ASPECTS. Sensitivity, specificity, Matthew's correlation coefficients (MCC), and receiver operating characteristic curves were generated for analysis before and after the software use., Results: Eps' performances improved when they used E-ASPECTS, with their results closer to those obtained by neuroradiologists. In the initial evaluation, MCC values for the two EPs were -0.01 and 0.04, respectively. After the software assistance, they obtained 0.38 and 0.43, respectively, which was closer to the scores obtained by the neuroradiologists (0.53 and 0.39, respectively)., Discussion: This is the first study that has specifically compared neuroradiologists' and EPs' performances before and after using E-ASPECTS. E-ASPECTS assisted and improved the evaluation of the images of patients with acute ischemic stroke., Conclusion: Artificial intelligence in the emergency room may increase the number of patients treated with tissue-type plasminogen activators., (© 2022 American Society of Neuroimaging.)

Background and Purpose: Recognizing the location and length of the thrombus responsible for large vessel occlusion in patients with acute ischemic stroke can facilitate effective endovascular recanalization therapy (ERT). We hypothesized that the aliasing or dipole effect produced by filtered-phase susceptibility-weighted imaging (SWI) would facilitate thrombus delineation., Methods: Of the patients with middle cerebral artery occlusion who underwent ERT, we screened those who underwent noncontrast CT (NCCT), multiphase CT angiography (mCTA), and SWI before the endovascular procedure. We used an arbitrary index termed measurement of equivalence in thrombus assessed by digital subtraction angiography (METAD) defined as having the same location as the thrombus observed in the digital subtraction angiography (DSA) and length differing by less than 5 mm. For NCCT, mCTA, SWI&#95;m (magnitude), and SWI&#95;p (phase), the length of the thrombus and METAD were assessed., Results: The mean lengths of the thrombi determined using NCCT, mCTA, SWI&#95;m, SWI&#95;p, and DSA were 14.03, 13.47, 13.89, 9.93, and 8.96 mm, respectively. The absolute agreement for thrombus length was excellent for SWI&#95;p and DSA (intraclass correlation coefficient [ICC] = .96), moderate for SWI&#95;m and DSA (ICC = .53), and poor for mCTA and DSA (ICC = .14). The METADs were 26.7%, 40.0%, 33.3%, and 73.3% for NCCT, mCTA, SWI&#95;m, and SWI&#95;p, respectively. The METADs for NCCT and SWI&#95;p were significantly different (p = .045) and those for mCTA and SWI&#95;m were not (p = .537 and .093, respectively)., Conclusions: The SWI&#95;p was best matched with the DSA for the measurement of the lengths and locations of thrombi. The use of pre-thrombectomy SWI&#95;p imaging for acute ischemic stroke may facilitate a successful ERT strategy., (© 2022 American Society of Neuroimaging.)

Background and Purpose: Treatment of acute ischemic stroke is heavily contingent upon time, as there is a strong relationship between time clock and tissue progression. Work has established imaging biomarker assessments as surrogates for time since stroke (TSS), namely, by comparing signal mismatch between diffusion-weighted imaging (DWI) and fluid-attenuated inversion recovery (FLAIR) imaging. Our goal was to develop an automatic technique for determining TSS from imaging that does not require subspecialist radiology expertise., Methods: Using 772 patients (66 ± 9 years, 319 women), we developed and externally evaluated a deep learning network for classifying TSS from MR images and compared algorithm predictions to neuroradiologist assessments of DWI-FLAIR mismatch. Models were trained to classify TSS within 4.5 hours and performance metrics with confidence intervals were reported on both internal and external evaluation sets., Results: Three board-certified neuroradiologists' DWI-FLAIR mismatch assessments, based on majority vote, yielded a sensitivity of .62, a specificity of .86, and a Fleiss' kappa of .46 when used to classify TSS. The deep learning method performed similarly to radiologists and outperformed previously reported methods, with the best model achieving an average evaluation accuracy, sensitivity, and specificity of .726, .712, and .741, respectively, on an internal cohort and .724, .757, and .679, respectively, on an external cohort., Conclusion: Our model achieved higher generalization performance on external evaluation datasets than the current state-of-the-art for TSS classification. These results demonstrate the potential of automatic assessment of onset time from imaging without the need for expertly trained radiologists., (© 2022 American Society of Neuroimaging.)

Background and Purpose: To determine the prognostic value for ischemic stroke or transitory ischemic attack (TIA) of plaque surface echogenicity alone or combined to degree of stenosis in a Swiss multicenter cohort METHODS: Patients with ≥60% asymptomatic or ≥50% symptomatic carotid stenosis were included. Grey-scale based colour mapping was obtained of the whole plaque and of its surface defined as the regions between the lumen and respectively 0-0.5, 0-1, 0-1.5, and 0-2 mm of the outer border of the plaque. Red, yellow and green colour represented low, intermediate or high echogenicity. Proportion of red color on surface (PRCS) reflecting low echogenictiy was considered alone or combined to degree of stenosis (Risk index, RI)., Results: We included 205 asymptomatic and 54 symptomatic patients. During follow-up (median/mean 24/27.7 months) 27 patients experienced stroke or TIA. In the asymptomatic group, RI ≥0.25 and PRCS ≥79% predicted stroke or TIA with a hazard ratio (HR) of respectively 8.7 p = 0.0001 and 10.2 p &lt; 0.0001. In the symptomatic group RI ≥0.25 and PRCS ≥81% predicted stroke or TIA occurrence with a HR of respectively 6.1 p = 0.006 and 8.9 p = 0.001. The best surface parameter was located at 0-0.5mm. Among variables including age, sex, degree of stenosis, stenosis progression, RI, PRCS, grey median scale values and clinical baseline status, only PRCS independently prognosticated stroke (p = 0.005)., Conclusion: In this pilot study including patients with at least moderate degree of carotid stenosis, PRCS (0-0.5mm) alone or combined to degree of stenosis strongly predicted occurrence of subsequent cerebrovascular events., (© 2022 The Authors. Journal of Neuroimaging published by Wiley Periodicals LLC on behalf of American Society of Neuroimaging.)

Mechanical thrombectomy (MT) for ischemic stroke due to large vessel occlusion is standard of care. Evidence-based guidelines on eligibility for MT have been outlined and evidence to extend the treatment benefit to more patients, particularly those at the extreme ends of a stroke clinical severity spectrum, is currently awaited. As patient selection continues to be explored, there is growing focus on procedure selection including the tools and techniques of thrombectomy and associated outcomes. Artificial intelligence (AI) has been instrumental in the area of patient selection for MT with a role in diagnosis and delivery of acute stroke care. Machine learning algorithms have been developed to detect cerebral ischemia and early infarct core, presence of large vessel occlusion, and perfusion deficit in acute ischemic stroke. Several available deep learning AI applications provide ready visualization and interpretation of cervical and cerebral arteries. Further enhancement of AI techniques to potentially include automated vessel probe tools in suspected large vessel occlusions is proposed. Value of AI may be extended to assist in procedure selection including both the tools and technique of thrombectomy. Delivering personalized medicine is the wave of the future and tailoring the MT treatment to a stroke patient is in line with this trend., (© 2022 American Society of Neuroimaging.)

Background and Purpose: The aim of this multicenter study was to compare the clinical outcome, safety, and efficacy of the full-length radiopaque Aperio Hybrid stent retriever (APH) with the precursor Aperio thrombectomy device (AP)., Methods: Multicentric retrospective analysis of patients with stroke, treated with the APH and AP due to an acute ischemic stroke by large vessel occlusions in the anterior or posterior circulation, was performed. We focused on the comparison of favorable clinical outcome (modified Rankin Scale, 0-2) after 3 months, favorable reperfusion rates (thrombolysis in cerebral infarction scale ≥ 2b), and the complication rate., Results: A total of 51 patients (female: n = 33, 64.7%, mean age 73 ± 16 years) with a median baseline National Institutes of Health Stroke Scale: 15 were treated with the APH or AP. Favorable outcome in patients treated with APH was excellent (44.0%) and comparable to the AP (36.8%). The rate of final favorable reperfusion for both devices was outstanding (APH 31/31 and AP 20/20). The overall complication rate for the APH was slightly higher compared to the AP (32.3%/15.0%). Symptomatic intracranial hemorrhage was recorded in 0 of 51 cases. The all-cause mortality rate at 90 days was 20.0% for the APH and comparable for the AP (21.1%)., Conclusions: Comparable clinical outcome, efficacy, and safety of the AP and the recently introduced APH were demonstrated. Both devices appeared feasible, efficient, and safe with regard to endovascular treatment in large vessel occlusion., (© 2022 American Society of Neuroimaging.)

Background and Purpose: Acute cerebral infarction in the basal ganglia is associated with an increased risk of cognitive impairment, suggesting that cognitive networks might be involved in neural plasticity after ischemic stroke. This study was conducted to explore the abnormalities in functional and causal connectivity of the brain network in patients with acute ischemic stroke (AIS) in the basal ganglia., Methods: Resting-state functional magnetic resonance imaging was performed in 27 patients with AIS in the basal ganglia and 27 healthy controls (HCs). Brain regions with statistically different degree centrality (DC) values between groups were selected as seed points for granger causality analysis (GCA) analysis. The effective connectivity values of GCA were extracted, and the correlation between them and the Montreal Cognitive Assessment (MoCA) score was analyzed., Results: Compared with HCs group, AIS patients displayed increased DC value in the left inferior temporal gyrus (ITG) and hippocampus head, reduced effective connectivity from the left ITG to the left precentral and postcentral gyri, increased effective connectivity from the left precentral and postcentral gyri to the left ITG, and reduced effective connectivity from the left anterior cingulate gyrus to the left ITG. The MoCA score of the AIS group was lower than that of the HCs group (t = -7.33, p < .05)., Conclusion: Alterations of functional and causal connectivity among multiple brain regions suggest that patients with AIS in the basal ganglia have impairment of multifunctional networks in the whole brain., (© 2022 American Society of Neuroimaging.)

Background and Purpose: This study aims to investigate the feasibility of a "real-time" estimate of the optimal CT perfusion (CTP) acquisition time (T op ) in ischemic stroke patients., Methods: The arterial input function, the venous output function (VOF), and the time-attenuation curves of ischemic core and ischemic penumbra of 51 patients with acute ischemic stroke in anterior circulation were obtained. The curves were analyzed to determine for each patient the T op value; additionally, several time parameters were derived from each waveform. The relationship between each of these parameters and T op was investigated., Results: We found a strong linear correlation between each time parameter derived from VOF curve and T op , suggesting that the VOF waveform is rescaled from patient to patient without significant change in shape., Conclusions: The linear correlation between T op and the VOF time to peak is well suited to implement a new technique to automatically customize the patient's CTP acquisition time. The method does not require an additional dose of contrast medium and does not increase the overall study time, so its use would be desirable to decrease the average radiation dose., (© 2022 American Society of Neuroimaging.)

Background and Purpose: The availability of cone-beam CT perfusion (CBCTP) in angiography suites may improve large-vessel occlusion (LVO) triage and reduce reperfusion times for patients presenting during extended time window. We aim to evaluate the perfusion maps correlation and agreement between multidetector CT perfusion (MDCTP) and CBCTP when obtained sequentially in patients undergoing endovascular therapy., Methods: This is a prospective, pilot, single-arm interventional cohort study of consecutive patients with anterior circulation LVO. All patients underwent MDCTP and CBCTP prior to endovascular therapy, generating cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), and time-to-maximum/time to peak contrast concentration maps. We compared the two imaging modalities using three different methods: (1) six regions of interest (ROIs) placed in the anterior circulation territory; (2) ROIs placed in all 10 Alberta Stroke Program Early CT Score regions; and (3) ROI drawn around the entire ischemic area. ROI ratios (unaffected/affected area) were compared for all sequences in each method. We used the intraclass correlation coefficient to calculate the correlation between the studies. Bland-Altman plots were also created to measure the degree of agreement. Finally, a sensitivity analysis was done comparing both modalities in patients with low infarct growth rate., Results: Fourteen patients were included (median age 81 years [74-87], 50% males, median National Institutes of Health Stroke Scale 19 [14-22]). Median time between studies was 42 minutes (interquartile range 29-61). Independently of the method used, we found moderate to excellent correlation in CBF, CBV, and MTT between modalities. CBF correlation further improved in patients with low infarct growth., Conclusion: These results demonstrate promising accuracy of CBCTP in evaluating ischemic tissue in patients presenting with LVO ischemic stroke., (© 2022 The Authors. Journal of Neuroimaging published by Wiley Periodicals LLC on behalf of American Society of Neuroimaging.)

Background and Purpose: Mechanical thrombectomy (MT) is standard care for patients suffering from an ischemic stroke due to a large vessel occlusion. Immediate and follow-up transcranial ultrasound examinations after MT were shown to have a diagnostic benefit. However, it is unclear whether repeated extracranial ultrasound after MT has an additional diagnostic yield, that is, depicts new findings., Methods: Retrospectively, from our prospective database we identified all patients after MT who presented for a follow-up examination between January 2017 and March 2020 and who had received an ultrasound examination after MT and at follow-up. Clinical data were extracted from our database. Ultrasound images of all patients were revisited to identify new findings at follow-up compared to examination after MT., Results: Ninety-one patients were identified appropriate for further analysis, with a mean age of 67.8 ± 16 years. Median National Institute of Health Stroke Scale at admission was 11 ± 8.5 points. At baseline ultrasound, 18 patients (19.8%) had no atherosclerotic alterations and 73 patients (82.2%) had a plaque burden of ≥1 plaque. During follow-up, in 5 patients (5.5%) a pathological finding presented in first examination evolved dynamically, that is, normalized. Vessel status of all other patients was stable, especially, in no patient a new relevant pathological finding occurred., Conclusions: Although sonographic normalization of pathologic findings was observed, pathologic new findings were not detected during follow-up. This study provides first data for a discussion of the role of ultrasound in a structured stroke care after MT. However, larger studies are required to improve the understanding., (© 2021 The Authors. Journal of Neuroimaging published by Wiley Periodicals LLC on behalf of American Society of Neuroimaging.)

Background and Purpose: White matter hyperintensities (WMHs) are associated with the presence of left ventricular hypertrophy (LVH). It is unclear if periventricular WMH (PV-WMH) and or deep WMH (D-WMH) are associated with LVH. We evaluated the association of PV-WMH and D-WMH with common transthoracic echocardiogram abnormalities, including LVH in acute ischemic stroke., Methods: PV-WMH and D-WMH were graded on a 0-3 score based on the Fazekas scale. Patients were categorized into clinically significant PV-WMH and D-WMH (score 2-3) and controls (score 0-1). Multivariate logistic regression analysis was performed to determine abnormalities on echocardiogram associated with PV-WMH and D-WMH., Results: Among 272 patients, 137 patients had PV-WMH and 93 patients had D-WMH with a score of 2-3 on Fazekas scale. Compared to controls, patients with PV-WMH (mean age±standard deviation: 60.8±14.4 vs. 73.8±11.2 years) and D-WMH (63.4±14.4 vs. 75.0±11.1 years) were older. Compared to controls, PV-WMH was associated with history of stroke (22 [16%] vs. 37 [27%], p = .03) and valvular calcification (33 [24%] vs. 61 [45%], p = .0005); D-WMH was associated with history of atrial fibrillation (25 [14%] vs. 22 [24%], p = .04), valvular calcification (50 [28%] vs. 44 [47%], p = .001), and LVH (30 [17%] vs. 25 [27%], p = .049). In multivariate analysis, PV-WMH was associated with age (odds ratio [OR] = 1.09; 95% confidence interval [CI] = 1.06-1.12) and stroke history (OR = 2.1; 95% CI = 1.1-4.1), and D-WMH was associated with age (OR = 1.07; 95% CI = 1.05-1.10) and LVH (OR = 2.0; 95% CI = 1.0-4.0)., Conclusion: LVH is associated with D-WMH but not with PV-WMH. Although valvular calcification is common, it is likely age related than due to WMH., (© 2021 American Society of Neuroimaging.)

Background and Purpose: Patent foramen ovale (PFO)is associated with cryptogenic stroke, especially in young adults. Transcranial Doppler (TCD) ultrasound is used as a screening tool before transesophageal echocardiography (TEE). However, the use of Valsalva maneuver (VM) to identify a right-to-left-shunt underlies interindividual variability. Here, we aimed to assess whether a pressure-controlled standardization of VM is useful to estimate PFO size., Methods: We included patients aged 18-80 years with a PFO according to TEE. Subjects underwent TCD with microembolic signals (MES) counted under four pressure conditions (i.e., at rest, 15 mbar, 40 mbar, and maximum expiratory pressure). Findings were correlated with TEE-based PFO size. The predictive value of TCD at rest and VM-based TCD for PFO size estimation was assessed by stepwise multivariate linear regression models and multiple cross-tab-analyses., Results: We screened 203 subjects after a cerebrovascular event, of which 78 (48 males [61.5%], median age 55 years [22-80]) with PFO were included. We found an association between MES count and expiratory pressure (p < .001). Predefined MES count categories at TCD pressure conditions correlated significantly with PFO size measured by TEE. We propose a PFO size estimation model based on TCD at rest and under VM, which classified PFO size correctly in 64.1% with the highest accuracy for small PFOs., Conclusion: Our data provide evidence that TCD with step-wise barometric standardization allows an estimation of PFO size with good accuracy. Though TCD will not replace TEE in future, this might be of clinical value in circumstances where TEE cannot be easily performed., (© 2021 The Authors. Journal of Neuroimaging published by Wiley Periodicals LLC on behalf of American Society of Neuroimaging.)

Background and Purpose: Ischemic diffusion-weighted imaging-fluid-attenuated inversion recovery (DWI-FLAIR) mismatch may be useful in guiding acute stroke treatment decisions given its relationship to onset time and parenchymal viability; however, it relies on subjective grading. Radiomics is an emerging image quantification methodology that may objectively represent continuous image characteristics. We propose a novel radiomics approach to characterize DWI-FLAIR mismatch., Methods: Ischemic lesions were visually graded for FLAIR positivity (absent, subtle, obvious) among consecutive large vessel occlusion stroke patients who underwent hyperacute MRI. Radiomic features were extracted from within the lesions on DWI and FLAIR. The DWI-FLAIR mismatch radiomics signature was built with features systematically selected by a cross-validated ElasticNet linear regression model of mismatch., Results: We identified 103 patients with mean age 68 ± 16 years; 63% were female. FLAIR hyperintensity was absent in 25%, subtle in 55%, and obvious in 20%. Inter-rater agreement for visual grading was moderate (Κ = .58). The radiomics signature of DWI-FLAIR mismatch included native FLAIR histogram kurtosis and local binary pattern-filtered FLAIR gray-level cluster shade; both correlated with visual grading (ρ = -.42, p < .001 and ρ = .40, p < .001, respectively)., Conclusions: Radiomics can describe DWI-FLAIR mismatch and may provide objective, continuous biomarkers for infarct evolution using clinical-grade images. These novel biomarkers may prove useful for treatment decisions and future research., (© 2021 American Society of Neuroimaging.)

Background and Purpose: Patients with acute ischemic stroke due to a large vessel occlusion (AIS-LVO) undergo emergent neuroimaging triage for thrombectomy treatment. MRI is often utilized for this evaluation, and cerebral magnetic resonance perfusion (MRP) imaging is used to identify the presence of the salvageable penumbra. To determine if dose reduction is feasible, we assessed whether a half-dose reduction in gadobenate provided sufficient MRP quality in AIS-LVO patients., Methods: A prospective observational study of all patients presenting to our neurovascular referral center with AIS-LVO was performed. MRP was done with a half-dose of gadolinium (0.1 ml/kg body weight) over a period of 10 months. MRP images were compared to a consecutive historical cohort of full-dose gadolinium (0.2 ml/kg body weight) MRP studies and rated for image quality (poor, borderline, or good) that determined thrombectomy eligibility., Results: Fifty-four half-dose and 127 full-dose patients were included. No differences in patient demographics or stroke presentation details were identified. MRP quality differed between half- and full-dose scans (p < 0.001), which were rated as poor (40.7% vs. 6.3%), borderline (18.5% vs. 26.8%), and good quality (40.7% vs. 66.9%), respectively. MRP image quality was then dichotomized into poor and sufficient (borderline and good) quality groups; half-dose studies were more likely to have poor quality compared to full-dose studies (40.7% vs. 6.3%; p < 0.001)., Conclusions: Half-dose gadolinium administration for MRP in AIS-LVO patients results in poor image quality in a substantial number of studies. MR cerebral perfusion performed with half-dose gadolinium may adversely affect stroke patient triage for thrombectomy., (© 2021 American Society of Neuroimaging.)

Background and Purpose: The significance of a bright vessel sign (BVS) at the site of a large vessel occlusion (LVO) on MR arterial spin labeling (ASL) sequence is not widely reported. We compared the utility of the ASL BVS to the gradient echo (GRE) susceptibility vessel sign (SVS) in heralding and localizing LVOs in a large cohort; most underwent digital subtraction angiography (DSA) and endovascular therapy for acute stroke., Methods: A total of 171 patients with large hemispheric stroke symptoms had baseline and follow-up MRIs with ASL, GRE, and MR angiogram (MRA). Scans were evaluated for (1) presence versus absence and (2) location of ASL BVS and GRE SVS. For patients who underwent DSA, data comparing presence and location of ASL BVS and GRE SVS to occlusions found on angiography, as well as resolution of the signs after successful recanalization, were also evaluated., Results: Compared to MRA, the sensitivity of the ASL BVS for an LVO was .83, significantly better than .67 for GRE SVS (p = .001). Localization of vessel occlusion was correct 60.4% of the time by ASL compared to 64.4% by GRE (p = .502). For the 107 patients who underwent DSA, the sensitivity of ASL BVS was .80 compared to .64 for GRE SVS (p = .009). Localization of LVO found on DSA was correct 63.5% of the time by ASL BVS compared to 72.9% by GRE SVS (p = .251)., Conclusion: ASL BVS is significantly more sensitive than GRE SVS for identification of LVO on both MRA and DSA., (© 2021 American Society of Neuroimaging.)

Background and Purpose: Complete reperfusion (TICI 3) after the first thrombectomy attempt or first pass effect (FPE) is associated with best clinical outcomes in large-vessel occlusion (LVO) acute ischemic stroke. While endovascular therapy techniques have improved substantially, FPE remains low (24-30%), and new methods to improve reperfusion efficiency are needed., Methods: In a prospective observational cohort study, 40 consecutive patients underwent cyclical aspiration thrombectomy using CLEAR TM Aspiration System (Insera Therapeutics Inc., Dallas, TX). Primary outcome included FPE with complete/near-complete reperfusion (TICI 2c/3 FPE). Secondary outcomes included early neurological improvement measured by the National Institute of Health Stroke Scale (NIHSS), safety outcomes, and functional outcomes using modified Rankin Scale (mRS). Outcomes were compared against published historical controls., Results: Among 38 patients who met criteria for LVO, median age was 75 (range 31-96). FPE was high (TICI 3: 26/38 [68%], TICI 2c/3: 29/38 [76%]). Among anterior circulation strokes, core lab-adjudicated FPE remained high (TICI 3: 17/29 [59%], TICI 2c/3: 20/29 [69%]), with excellent final successful revascularization results (Final TICI 3: 24/29 [83%], Final TICI 2c/3: 27/29 [93%]). FPE in the CLEAR-1 cohort was significantly higher compared to FPE using existing devices (meta-analysis) from historical controls (TICI 2c/3: 76% vs. 28%, p = 0.0001). High rates of early neurological improvement were observed (delta NIHSS≥4: 35/38 [92.1%]; delta NIHSS≥10: 27/38 [71%]). Similarly, high rates of good functional outcomes (mRS 0-2: 32/38 [84%]) and low mortality (2/38 [5%]) were observed., Conclusion: Cyclical aspiration using the CLEAR TM Aspiration System is safe, effective, and achieved a high TICI 3 FPE for large-vessel strokes., (© 2021 The Authors. Journal of Neuroimaging published by Wiley Periodicals LLC on behalf of American Society of Neuroimaging.)

Background and Purpose: The first pass effect has been reported as a mechanical thrombectomy (MT) success metric in patients with large vessel occlusive stroke. We aimed to compare the clinical and neuroimagign outcomes of patients who had favorable recanalization (mTICI 2c or mTICI 3) achieved in one pass versus those requiring multiple passes., Methods: In this "real-world" multicenter study, patients with mTICI 2c or 3 recanalization were identified from three prospectively collected stroke databases from January 2016 to December 2019. Clinical outcomes were a favorable functional outcome at 90 days (modified Rankin Scale score 0-2), and the rate of symptomatic intracranial hemorrhage (ICH) any ICH, and 90-day mortality., Results: Favorable recanalization was achieved in 390/664 (59%) of consecutive patients who underwent MT (age 71.2 ± 13.2 years, 188 [48.2%] women). This was achieved after a single thrombectomy pass (n = 290) or multiple thrombectomy passes (n = 100). The rate of favorable clinical outcome was higher (41% vs. 28 %, p = .02) in the first pass group with a continued trend on multivariate analysis that did not reaching statistical significance (OR 1.68 95% confidence interval [CI] 1.0-2.95, p = .07). Similarly, the odds of any ICH were significantly lower (OR 0.56 CI 0.32-0.97, p = .03). A similar trend of favorable clinical outcomes was noticed on subgroup analysis of patients with M1 occlusion (OR 1.81 CI 1.01-3.61, p = .08)., Conclusion: The first-pass reperfusion was associated with a trend toward favorable clinical outcome and lower rates of ICH. These data suggest that the first-pass effect should be the mechanical thrombectomy procedure goal., (© 2021 American Society of Neuroimaging.)

Background and Purpose: A prior study found a link between post-stroke blood-brain barrier disruption and functional outcomes. The current study aimed to replicate this finding in a cohort of patients recruited in the context of a randomized clinical trial., Methods: The ACTION trial was a study of natalizumab in acute stroke patients. Patients with MRI-perfusion weighted imaging (PWI) were included in this post-hoc analysis. Blood-brain permeability images (BBPI) were calculated from the PWI source images. Mean BBPI values from the 24 h time point were compared with modified Rankin scores (mRS) at 5, 30, and 90-day assessments using linear regression. Good functional outcome (mRS< = 1) was compared with mean BBPI using logistic regression., Results: One hundred and nineteen patients were included in the analysis (median age = 74, 43% female). Higher mean BBPI was associated with worse mRS at 5 days (p = 0.002; r 2 = 0.078) and 30 days (p = 0.036; r 2 = 0.039) but did not reach statistical significance at 90 days (p = 0.30; r 2 = 0.010). When removing high-value outliers, all outcome measures showed a stronger relationship with mean BBPI. Logistic regression found that with every 1% increase in mean BBPI measured 24 h after the stroke, the likelihood of achieving a good functional outcome at 90 days is decreased by half (OR = 0.53; CI = 0.30:0.95; p = 0.032)., Conclusions: With sufficient image quality, elevated BBPI measured in the days after an ischemic event is predictive of worse functional outcome and may serve as a biomarker for post-stroke inflammation., (© 2021 American Society of Neuroimaging.)

Background and Purpose: Intracranial vessel imaging by time-of-flight MR angiography (TOF-MRA) is one of the most frequently performed investigations in clinical neuroradiology. Particularly in the acute setting, fast imaging is needed for diagnostics, with a sequence ideally depicting even small vessels. The purpose of this study was to compare image and diagnostic quality of a novel ultrashort TOF-MRA sequence accelerated by spiral imaging (TOF-Spiral-short) to a standard TOF-MRA sequence accelerated by compressed sensing (TOF-CS) and to CT angiography (CTA)., Methods: Forty-one patients (36.6% showing vessel pathologies) who had undergone TOF-CS (acquisition duration: 4 minutes 8 seconds), TOF-Spiral-short (acquisition duration: 51 seconds; spiral imaging [accelerating factor 1.3], decreased field of view [accelerating factor 1.2], and increased voxel size [accelerating factor 3.3]), and CTA were retrospectively evaluated. Assessment of image quality, diagnostic confidence, and quantification of stenosis or aneurysm diameter were performed by two readers., Results: Image quality at the skull base was slightly reduced with TOF-Spiral-short compared to CTA and TOF-CS (P < .05). Delineation of small intracranial vessels was improved by TOF-Spiral-short compared to CTA (P < .0001). In TOF-Spiral-short, diagnostic confidence was not reduced compared to TOF-CS in patients with vessel pathologies. We observed no significant difference in quantitative pathology assessment between TOF-Spiral-short and the other two modalities. TOF-Spiral-short enabled the correct identification of all vessel pathologies., Conclusions: Accelerating TOF-MRA of brain-feeding arteries by a novel ultrashort spiral imaging sequence shows adequate image quality and sufficient diagnostic performance. Thus, TOF-Spiral-short holds potential for fast and reliable diagnostics of vessel pathologies, particularly in the acute setting., (© 2020 The Authors. Journal of Neuroimaging published by Wiley Periodicals LLC on behalf of American Society of Neuroimaging.)

Background and Purpose: Although transcranial Doppler detects microembolic signals (MES) in numerous settings, the practical significance of such findings remains unclear., Methods: Clinical information from ischemic stroke or transient ischemic attack patients (n = 248) who underwent embolic monitoring from January 2015 to December 2018 was obtained., Results: MES were found in 15% of studies and ischemic recurrence was seen in 11% of patients (over 7 ± 6 days). Patients with MES had more lacunes than those without MES (1 ± 3 vs. 1 ± 2, P = .016), were more likely to have ischemic recurrence (37% vs. 6%, P < .001), undergo a future revascularization procedure (26% vs. 10%, P = .005), have a longer length of stay (9 vs. 4 days, P = .043), and have worse functional disability at discharge (modified Rankin Scale 3-6, 66% vs. 34%, P < .001). After controlling for several relevant cofactors, patients with MES were more likely to have ischemic recurrence (HR 4.90, 95% CI 2.16-11.09, P < .001), worse functional disability (OR 3.31, 95% CI 1.22-8.99, P = .019), and longer length of stays (β = .202, P < .001)., Conclusions: MES may help to risk stratify patients as their presence is associated with ischemic recurrence and worse outcomes., (© 2020 American Society of Neuroimaging.)

Sickle cell disease is the most common hereditary hemoglobinopathy, which results in abnormally shaped and rigid red blood cells. These sickle-shaped red blood cells cause vaso-occlusion and ischemic phenomena that can affect any organ in the body. As a common cause of disability, the neurological manifestations of sickle cell disease are particularly important. Neuroimaging has a crucial role in the diagnosis, management, and prevention of the complications of sickle cell disease. These complications can affect the brain parenchyma, vasculature, and skull and can be ascribed directly or indirectly to a vasculopathy of small and large vessels. Vaso-occlusion can cause ischemic stroke. Ischemic damage in the absence of an acute neurological deficit, and therefore only apparent on neuroimaging, is termed silent cerebral ischemia. Weakening of the arterial walls can cause aneurysms. In its most severe form, a vasculopathy of the terminal internal carotid arteries can progress to moyamoya syndrome, characterized by steno-occlusive disease and the formation of friable collateral arteries. Rupture of aneurysms or friable collateral arteries is a potential cause of intracranial hemorrhage. The skull and vertebrae may be affected by extra-medullary hematopoiesis, due to severe anemia, or iron deposition, due to chronic red blood cell transfusion. Impaired blood supply to bone is associated with osteomyelitis and osteonecrosis. Fat embolization syndrome is a rare complication of osteonecrosis, which may cause devastating neurological impairment. Awareness and early recognition of the diverse manifestations of sickle cell disease on neuroimaging is crucial to ensure optimal treatment in a complex patient cohort., (© 2020 The Authors. Journal of Neuroimaging published by Wiley Periodicals LLC on behalf of American Society of Neuroimaging.)

Background and Purpose: The brainstem plays a key role in the control of respiration. Strokes involving the lateral medulla can rarely produce a central hypoventilation syndrome (CHS) characterized by loss of automatic respiration called Ondine's curse. In this study, we investigated the neuroanatomical correlates of CHS in patients with lateral medullary infarction (LMI)., Methods: Cases of CHS following LMI were identified from searching our medical records and literature. Voxel-based lesion-symptom mapping and lesion network-symptom-mapping (LNSM) analysis was performed to identify the regions connected to the lesion sites based on normative functional connectome data., Results: Sixteen patients with CHS and 32 controls were included. The ventro-lateral region of the rostral medulla showed a significant association with CHS. LNSM analysis showed connections of this region to the rostral ventro-lateral medulla and caudal pons., Conclusions: In patients with LMI, disruption of the respiratory control network, at the level of ventro-lateral region of the rostral medulla, could result in CHS., (© 2020 American Society of Neuroimaging.)

Background and Purpose: The changing MRI signal accompanying brain maturation in fetal brains can be quantified on apparent diffusion coefficient (ADC) maps. Deviations from the natural course of ADC values may reflect structural pathology. The purpose of this study was to determine the influence of fetal pathologies on the ADC values in different regions of the fetal brain and their evolution with increasing gestational age., Methods: This was a retrospective study of 291 fetuses evaluated between the 14th and the 40th week of gestation using diffusion-weighted imaging (DWI). Fetuses with normal MRI findings but sonographically suspected pathology or fetuses with abnormalities not affecting the brain were analyzed in the control group and compared to fetuses suffering from different pathologies like hydrocephalus/ventriculomegaly, brain malformations, infections, ischemia/hemorrhage, diaphragmatic hernias, and congenital heart disease. Pairwise ADC measurements in each side of the white matter (WM) of the frontal, parietal, and occipital lobes, in the basal ganglia and the cerebellum, as well as a single measurement in the pons were performed and were plotted against gestational age., Results: In the control group, brain maturation followed a defined gradient, resulting in lower ADC values in the most mature regions. Each disorder group experienced abnormal patterns of evolution of the ADC values over time deviating from the expected course., Conclusions: The ADC values in different regions of the fetal brain and their evolution with increasing gestational age are influenced by pathologies compromising the cerebral maturation., (© 2020 The Authors. Journal of Neuroimaging published by Wiley Periodicals LLC on behalf of American Society of Neuroimaging.)

Background and Purpose: Recent trials have shown benefit of thrombectomy in patients selected by penumbral imaging in the late (>6 hours) window. However, the role penumbral imaging is not clear in the early (0-6 hours) window. We sought to evaluate if time to treatment modifies the effect of endovascular reperfusion in stroke patients with evidence of salvageable tissue on CT perfusion (CTP)., Methods: We retrospectively analyzed consecutive patients who underwent thrombectomy in a single center. Demographics, comorbidities, National Institute of Health Stroke Scale (NIHSS), rtPA administration, ASPECTS, core infarct volume, onset to skin puncture time, recanalization (mTICI IIb/III), final infarct volume were compared between patients with good and poor 90-day outcomes (mRS 0-2 vs. 3-6). Multivariable logistic regression analyses were used to identify independent predictors of a good (mRS 0-2) 90-day outcome., Results: A total of 235 patients were studied, out of which 52.3% were female. Univariate analysis showed that the groups (early vs. late) were balanced for age (P = .23), NIHSS (P = .63), vessel occlusion location (P = .78), initial core infarct volume (P = .15), and recanalization (mTICI IIb/III) rates (P = .22). Favorable outcome (mRS 0-2) at 90 days (P = .30) were similar. There was a significant difference in final infarct volume (P = .04). Shift analysis did not reveal any significant difference in 90-day outcome (P = .14). After adjustment; age (P < .001), NIHSS (P = .01), recanalization (P = .008), and final infarct volume (P < .001) were predictive of favorable outcome., Conclusions: Penumbral imaging-based selection of patients for thrombectomy is effective regardless of onset time and yields similar functional outcomes in early and late window patients., (© 2020 by the American Society of Neuroimaging.)

Background and Purpose: The 2018 AHA guidelines recommend perfusion imaging to select patients with acute large vessel occlusion (LVO) for thrombectomy in the extended window. However, the relationship between noncontrast CT and CT perfusion imaging has not been sufficiently characterized >6 hours after last known normal (LKN)., Methods: From a multicenter prospective cohort of consecutive adults who underwent thrombectomy for anterior LVO 0-24 hours after LKN, we correlated baseline core volume (rCBF < 30%) and the Alberta Stroke Program Early CT Scale (ASPECTS) score. We compared perfusion findings between patients with an unfavorable ASPECTS (<6) against those with a favorable ASPECTS (≥6), and assessed findings over time., Results: Of 485 enrolled patients, 177 met inclusion criteria (median age: 69 years, interquartile range [IQR: 57-81], 49% female, median ASPECTS 8 [IQR: 6-9], median core 10 cc [IQR: 0-30]). ASPECTS and core volume moderately correlated (r = -.37). A 0 cc core was observed in 54 (31%) patients, 70% of whom had ASPECTS <10. Of the 28 patients with ASPECTS <6, 3 (11%) had a 0 cc core. After adjustment for age and stroke severity, there was a lower ASPECTS for every 1 hour delay from LKN (cOR: 0.95, 95% confidence of interval [CI]: 0.91-1.00, P = .04). There was no difference in core (P = .51) or penumbra volumes (P = .87) across patients over time., Conclusions: In this multicenter prospective cohort of patients who underwent thrombectomy, one-third of patients had normal CTP core volumes despite nearly three quarters of patients showing ischemic changes on CT. This finding emphasizes the need to carefully assess both noncontrast and perfusion imaging when considering thrombectomy eligibility., (© 2019 by the American Society of Neuroimaging.)

Background and Purpose: In the setting of an extended time window for endovascular treatment (EVT) for acute stroke patients, computed tomography perfusion (CTP) has become a major tool in patient selection. However, there are some data suggesting that the initial ischemic core may be overestimated by CTP depending on stroke onset time. This study aims to evaluate possible predictors of overestimation of infarct core by CTP., Methods: We studied all consecutive stroke patients undergoing EVT during 1 year who underwent CTP at admission and had a successful recanalization. Admission infarct core was measured on cerebral blood volume maps generated using the Intellispace Portal (Philips Healthcare, Best, the Netherlands) and final infarct was measured on noncontrast follow-up computed tomography at 24 hours. We defined overestimation of the infarct core as initial core minus final infarct >10 mL., Results: Out of 107 patients undergoing EVT in the study period, 60 were anterior circulation and had CTP done at our institute, and of them 31 were compatible with the inclusion criteria (known time of onset, no hemorrhagic conversion, and good recanalization). Median National Institute of Health Stroke Scale on admission was 13. Median time from symptoms to CTP was 148 minutes. Seventeen patients were found to have overestimation of the infarct core. Logistic regression analyses showed time from symptom onset to CTP to be inversely related to overestimation with a cutoff of 170 minutes (sensitivity 94% and specificity 43%)., Conclusion: Over estimation of the infarct core by CTP in patients undergoing EVT is time dependent and so CTP results among early arrivers should be interpreted cautiously., (© 2020 by the American Society of Neuroimaging.)

Disability and effectiveness of physical therapy are highly variable following ischemic stroke due to different brain regions being affected. Functional magnetic resonance imaging (fMRI) studies of patients in the months and years following stroke have given some insight into how the brain recovers lost functions. Initially, new pathways are recruited to compensate for the lost region, showing as a brighter blood oxygen-level-dependent (BOLD) signal over a larger area during a task than in healthy controls. Subsequently, activity is reduced to baseline levels as pathways become more efficient, mimicking the process of learning typically seen during development. Preclinical models of ischemic stroke aim to enhance understanding of the biology underlying recovery following stroke. However, the pattern of recruitment and focusing seen in humans has not been observed in preclinical fMRI studies that are highly variable methodologically. Resting-state fMRI studies show more consistency; however, there are still confounding factors to address. Anesthesia and method of stroke induction are the two main sources of variability in preclinical studies; improvements here can reduce variability and increase the intensity and reproducibility of the BOLD response detected by fMRI. Differences in task or stimulus and differences in analysis method also present a source of variability. This review compares clinical and preclinical fMRI studies of recovery following stroke and focuses on how refinement of preclinical models and MRI methods may obtain more representative fMRI data in relation to human studies., (© 2019 The Authors. Journal of Neuroimaging published by Wiley Periodicals, Inc. on behalf of American Society of Neuroimaging.)

Background and Purpose: Evidence suggests that cardioembolism represents the underlying mechanism in the minority of embolic strokes of undetermined source (ESUS). In this population-based study, we sought to compare the clinical and imaging characteristics as well as outcomes in patients with ESUS and cardioembolic stroke (CE)., Methods: We included consecutive patients with first-ever ischemic stroke (IS) from the previously published population-based Evros-Stroke-Registry identified as ESUS or CE according to standardized criteria. Baseline characteristics, admission NIHSS scores, cerebral edema, hemorrhagic transformation, stroke recurrence, functional outcomes (determined by modified Rankin Scale [mRS] scores), and mortality rates were recorded during the 1-year follow-up period., Results: We identified 21 ESUS (3.7% of IS) and 211 CE (37.1% of IS) cases. Patients with ESUS were younger (median age: 68 years [interquartile range [IQR]: 61-75] vs 80 years [IQR: 75-84]; P < .001), had lower median admission NIHSS scores (4 points [IQR: 2-8] vs 10 points [IQR: 5-17]; P < .001), and lower prevalence of cerebral edema on neuroimaging studies (0 vs. 33.3%, P = .002). Functional outcomes were more favorable in ESUS at 28 (median mRS score: 2 [IQR: 1-3] vs 4 [IQR: 4-5]; P < .001), 90 (median mRS score: 1 [IQR: 0-2] vs 4 [IQR: 3-5]; P < .001), and 365 days (median mRS score: 1 [IQR: 0-2] vs 4 [IQR: 2-4]; P < 0.001). At 1-year, the mortality rate was lower in ESUS (0% [95% confidence interval [CI]: 0-13.5%] vs 34.6% [95% CI: 28.2-41.0%]; P < .001); the 1-year recurrent rate was also lower numerically (0% [95% CI: 0-13.5%] vs 9.5% [95% CI: 5.5-13.4%]; P = .140) but this difference failed to reach statistical significance due to the small study population., Conclusions: The clinical and neuroimaging profiles as well as clinical outcomes vary substantially between ESUS and CE indicating different underlying mechanisms., (© 2019 by the American Society of Neuroimaging.)

Background and Purpose: Studies have shown an association between infarct patterns and recurrent stroke in patients with symptomatic intracranial stenosis (sICAS) but there are limited data on associations with perfusion imaging mismatch profile. We aim to determine the association between infarct pattern, optimal mismatch profile definition, and recurrent cerebrovascular events (RCVE) in patients with anterior circulation sICAS., Methods: This is a retrospective study of consecutive patients with acutely sICAS admitted to a comprehensive stroke center over 18 month's period. Patients with sICAS underwent magnetic resonance perfusion (MRP) imaging within 24 hours from admission. Infarct patterns (internal BZ [IBZ], cortical BZ [CBZ], and core/perforator [C/P]) and RCVE within 90 days, were independently adjudicated by two reviewers. We compared mismatch profiles and recurrent event rates across infarct patterns., Results: Twenty-five patients met inclusion criteria; 28% had IBZ infarcts and overall RCVE rate was 32.0%. When compared to patients without IBZ infarcts, those with IBZ infarcts were more likely to have a target mismatch profile using T max > 6 seconds (60% vs. 6.7%, P = .007) and RCVE (62.5% vs. 11.8%, P = .01). There were no associations between CBZ and C/P infarcts and target mismatch profiles and RCVE., Conclusion: IBZ infarcts may be a surrogate marker of distal perfusion status and RCVE risk. Larger multicenter, prospective, core-lab blindly adjudicated studies are needed to confirm our findings., (© 2019 by the American Society of Neuroimaging.)

Background and Purpose: Automated computed tomography perfusion (CTP) is recommended to inform selection of stroke patients for thrombectomy >6 hours from last known normal (LKN). However, artifacts on automated perfusion output may overestimate the tissue at risk leading to misclassification of thrombectomy eligibility in some patients., Methods: We conducted a retrospective multisite study of consecutive patients with anterior large vessel occlusion (LVO) undergoing CTP (6/2017-12/2017). The primary outcome was the RAPID automated T max  > 6 seconds volume that was discordant with clinical symptoms and vessel imaging, manually assessed by two independent readers. The discordant penumbral volume was compared to the automated output and corrected mismatch ratios were generated., Results: Of 410 consecutive patients who underwent CTP for suspected stroke, 60 (15%) had acute anterior circulation LVO. Of these, 26 (43%) had T max > 6 seconds abnormalities discordant with clinical symptoms and vessel imaging. There was strong interrater agreement on artifact volume (r 2 = 0.927). Among patients with discordant T max imaging, the median artifactual volume was 12cc (IQR 3-21cc), accounting for a median of 8% of the automated T max > 6 seconds volume (IQR 3-16%, range 1-64%). Recalculation of the T max > 6 seconds volume resulted in 1 patient being reclassified as having an "unfavorable" mismatch ratio (2.04-1.40)., Conclusion: Nearly half of patients had evidence of artifactual penumbral imaging on automated CTP, which rarely lead to misclassification of thrombectomy eligibility. Although artifactual findings are reliably identified by trained raters, our results emphasize the need to evaluate CTP results with knowledge of the patient's clinical symptoms and vascular imaging., (© 2019 by the American Society of Neuroimaging.)

Background and Purpose: There is evidence suggesting that Los Angeles Motor Scale (LAMS) ≥ 4 predicts large vessel occlusion (LVO). We aim to determine whether atrial fibrillation (AF) can improve the ability of LAMS in predicting LVO., Methods: We included consecutive patients with a discharge diagnosis of ischemic stroke admitted within 24 hours from last known normal time who underwent emergent vascular imaging using a computerized tomography angiography (CTA) of the head and neck. LVO was defined as intracranial internal carotid artery, proximal middle cerebral artery (M1 or proximal M2 segment), or basilar occlusion. LAMS was determined in the emergency department upon arrival. Univariate and multivariable models were performed to identify predictors of LVO and to determine whether AF improves the ability of LAMS to predict LVO., Results: Among 1,234 patients admitted with ischemic stroke, 862 underwent emergent vascular imaging (69.8%) out of which 374 (43.4%) had evidence of LVO and 207 (24%) underwent mechanical thrombectomy. In multivariable models, predictors of LVO were LAMS (OR 1.42 per one point increase 95% CI 1.29-1.57) and AF (OR 1.95 95% CI 1.26-3.02, P < .001). We developed the LAMS-AF that includes the LAMS score and adds two points if AF is present. In this analysis, LAMS-AF (AUC .78) had improved prediction over LAMS (AUC .76) in predicting LVO and lead to reclassification of 8/68 patients (11.8%) with LAMS = 3 group into the high-risk LVO group., Conclusion: In patients with LAMS = 3, using the LAMS-AF score may improve the ability of LAMS in predicting LVO. Larger studies are needed to confirm our findings., (© 2019 by the American Society of Neuroimaging.)

Background and Purpose: Identifying a last known well (LKW) time surrogate for acute stroke is vital to increase stroke treatment. Diffusion-weighted imaging (DWI) signal intensity initially increases from onset of stroke but mapping a reliable time course to the signal intensity has not been demonstrated., Methods: We retrospectively reviewed stroke code patients between 1/2016 and 6/2017 from the prospective; Institutional review board (IRB) approved University of California San Diego Stroke Registry. Patients who had magnetic resonance imaging of brain from onset, with or without intervention, are included. All ischemic strokes were confirmed and timing from onset to imaging was calculated. Raw DWI intensity is measured using IMPAX software and compared to contralateral side for control for a relative DWI intensity (rDWI). LKW and magnetic resonance imaging (MRI) time were collected by chart review. Correlation is assessed using Pearson correlation coefficient between DWI intensity, rDWI, and time to MRI imaging. 1.5T, 3T, and combined modalities were examined., Results: Seventy-eight patients were included in this analysis. Overall, there was statistically significant positive correlation (.53, P < .001) between DWI intensity and LKW time irrespective of scanner strength. Using 1.5T analyses, there was good correlation (.46, P < .001). 3T MRI analysis further showed comparatively stronger positive correlation (.66, P < .001)., Conclusions: There is good correlation between DWI intensity and minutes from onset to MRI. This suggests a time-dependent DWI intensity response and supports the potential use of DWI intensity measurements to extrapolate an LKW time. Further studies are being pursued to increase both experience and generalizability., (© 2019 by the American Society of Neuroimaging.)

Background and Purpose: Hemodynamic and metabolic impairment in intracranial atherosclerotic stenosis (ICAS) may promote stroke vulnerability particularly in borderzone areas. Perfusion and oxygen mapping magnetic resonance imaging (MRI) may provide useful information in this setting., Methods: In this pilot study, patients with symptomatic atherosclerotic anterior circulation stenosis ≥60%, without other sources of ischemic stroke, were included. High-resolution vessel wall MRI quantified the stenosis degree, and hemodynamic and metabolic impairment was assessed at baseline using dynamic susceptibility contrast perfusion and multiparametric quantitative blood-oxygen-level-dependent (mqBOLD) oxygenation MRI. All parameters were assessed within both hemispheres and in borderzone areas., Results: Forty-three subjects with intracranial artery narrowing were screened from November 2014 to January 2016. Eleven patients met the study criteria (mean ± standard deviation age = 64.4 ± 10.6 years, the mean degree of stenosis was 76.9 ± 23.4%). No interhemispheric differences were observed across oxygen (cerebral metabolic rate of oxygen and tissular saturation of oxygen) or perfusion (mean transit time, time to maximum, T max , normalized cerebral blood volume [nCBV], and normalized cerebral blood flow) parameters. A positive correlation was observed between the stenosis degree and ipsilateral nCBV (R = .77, P = .008). In addition, a significant increase in CBV was observed in anterior cortical borderzones ipsilateral to stenosis (nCBV = 7.20 ± 1.81 vs. 5.45 ± 1.40 mL/100 g, P = .02)., Conclusion: Symptomatic ICAS had no global impact on perfusion and oxygen mapping MRI at resting state. A significant increase in nCBV was found within anterior borderzone areas., (© 2019 by the American Society of Neuroimaging.)

Pediatric arteriopathies are increasingly recognized in school-aged children with a variety of presenting symptoms ranging from headache, seizures, encephalopathy, and neuropsychiatric symptoms as well as focal neurologic deficits due to acute ischemic strokes. However, unlike the adult stroke population, there are differences in the clinical manifestations, the stroke mechanism, and risk factors in pediatric ischemic stroke. There has been increasing awareness and recognition of pediatric cerebral arteriopathies as a predominant stroke etiology. Prompt diagnosis of arteriopathies is essential to limit injury and prevent recurrent stroke. Based on predominant vessels involved and clinical symptoms, these arteriopathies can be broadly divided into two categories: large-medium size arteriopathies and small vessel arteriopathies. Each category can be further divided into inflammatory and noninflammatory according to their etiologies. The ability to distinguish between inflammatory and noninflammatory etiologies carries major prognostic implications for acute management and secondary stroke prevention as well as screening for systemic complications and counseling., (© 2019 by the American Society of Neuroimaging.)

Background and Purpose: Mechanical thrombectomy has been shown to be effective for acute stroke treatment, but lesions of cerebral vessels can develop thereafter. Such lesions of recanalized vessels and altered cerebral hemodynamics after mechanical thrombectomy are poorly investigated. In particular for neurosonography, data are sparse. We aimed to describe hemodynamic changes and incidence of de-novo stenosis after mechanical thrombectomy with neurosonography., Methods: Retrospective analysis of patients after successful mechanical thrombectomy for acute stroke therapy who received one neurosonography at baseline and during follow up. Peak systolic velocity (PSV) of all intracranial recanalized and reference vessels was extracted for analysis. Patients with an isolated increase or decrease of PSV (50% or 50 cm/second for anterior and 30% or 30 cm/second for posterior circulation) were identified and characterized., Results: Eighty-eight patients (mean age 64.4; 34.1% female) were included in this study. In 9 (10.2%) patients, the vessel occlusion was located in the posterior, and in 79 (89.9%) patients the vessel occlusion was located in the anterior circulation. With predominance to the recanalized vessel, mean PSV decreased at both, the recanalized and the reference vessel during follow up. In 3 (3.4%) patients, an isolated increase of PSV was observed in the recanalized vessel, and in 6 (6.8%) patients an isolated decrease of PSV was observed in the recanalized vessel., Conclusion: Sonographic incidence of de-novo stenosis following mechanical thrombectomy seems to be low, in line with prior angiographic studies. However, as measured by neurosonography, cerebral hemodynamic in the recanalized vessel is dynamic after thrombectomy. This result is of interest for further prospective analysis., (© 2019 by the American Society of Neuroimaging.)

Background and Purpose: The validity of CT perfusion (CTP) predictions of expected infarction volume ("at risk" tissue) without rapid recanalization remains poorly characterized., Methods: From the MR CLEAN trial, we included patients who underwent CTP without successful recanalization. "At risk" volume was defined as T max > 6 seconds and ischemic core as relative CBF < 30 (Olea Sphere). Coprimary outcomes were follow-up infarct volume (FIV) on CT at 1-5 days and 90-day mRS. Data are presented as median [IQR] or OR [95% CI] unless otherwise specified., Results: Among 37 patients who met criteria, 14 (38%) were women, median age was 61 years [52-69], NIHSS was 19 [15-21], ASPECTS was 8 [7-9], and onset to imaging was 160 minutes [39-200]. Occlusion location was M1 for 22 (59%), ICA-T in 10 (27%), and M2 in 4 (11%). In univariable analysis, "at risk" volume correlated poorly with FIV (r = .06, P = .77). Among patients with predicted "at risk" volume < 100 mL, 36% had FIV > 200 mL. In adjusted linear regression, NIHSS but not "at risk" volume was associated with FIV (Coef 12, P = .045; Coef -.15, P = .8). In adjusted logistic regression, NIHSS but not "at risk" volume was associated with mRS 0-2 at 90 days (OR .7 [.5-.99]; OR 1.0 [.99-1.04])., Conclusion: Predictions of "at-risk" tissue using CTP may underestimate the natural history of infarction from acute large vessel occlusions. NIHSS may perform better as a predictor of clinical outcomes in patients without rapid recanalization., (© 2019 by the American Society of Neuroimaging.)

Background and Purpose: Infarct core assessment on presentation is important to evaluate salvageable tissue to select patients for thrombectomy. Our study aims to evaluate the correlation between infarct core volume measured by computed tomography (CT) perfusion (CTP) and magnetic resonance diffusion-weighted imaging (MR-DWI) in patients with acute large-vessel occlusion., Methods: We studied patients who underwent CTP on presentation to the emergency department for stroke symptoms. National Institute of Health Stroke Scale (NIHSS), collateral status, symptomatic vessels, and modified Rankin scale (mRS) at 90 days were collected. Admission infarct core volume was measured on initial relative cerebral blood volume and final infarct core volume on follow-up DWI. The correlation between two measures was assessed using Pearson's correlation coefficient., Results: Seventy-four patients were studied of which 41.9% were female. Median NIHSS was 13 (2-30). Middle cerebral artery occlusion was present in 53 (71.6%) patients and 54 (72.9%) had good collaterals. Good functional outcome of mRS 0-2 was achieved by 60.8% at 90 days. There was a strong correlation between CTP and MR-DWI (r = .94). There was no significant difference between volume (in milliliters) on CTP (54.1 ± 69.8) and volume on DWI (50.3 ± 59.7; P = .18) using the paired t-test., Conclusion: CTP provides a good estimation of the core infarct volume. It performs well within the clinically relevant thresholds for patient selection for thrombectomy., (© 2019 by the American Society of Neuroimaging.)

Acute multi-territory, embolic cerebral infarctions are often associated with serious underlying clinical conditions including the presence of highly "active" emboligenic sources causing that in turn may result in high early recurrence rates. Prompt diagnosis, risk stratification, and treatment are substantial for the prevention of subsequent embolization that would result in further clinical deterioration. Among other clinical investigations, transcranial Doppler (TCD) monitoring is highly efficacious for the detection of microembolic signals (MES) that correspond to microthrombi entering the intracranial circulation. The presence and burden of MES, especially in multiple intracranial arteries, is clearly associated with an increased risk of symptomatic, recurrent embolization, and thus can justify a more aggressive treatment approach (clopidogrel load followed by dual antiplatelet therapy or alternatively therapeutic dose of low-molecular-weight heparin). In this narrative review, we discuss the most important causes of multi-territory embolic ischemic strokes and also underscore the utility of TCD as a noninvasive tool for the diagnosis, risk stratification, and treatment., (© 2019 by the American Society of Neuroimaging.)

Background and Purpose: This study aims to investigate the significance of regional hyperperfusion (RH) detected by arterial spin labeling (ASL) in a group of untreated stroke patients, within 24-36 hours after symptom onset. The relationship between RH volume and infarcted volume (DIV) as defined on diffusion weighted images (DWIs) was evaluated., Methods: Of the 346 consecutive acute stroke patients who attended our center, we retrospectively reviewed MRI studies of 47 patients who were ineligible for standard treatment with intravenous tissue plasminogen activator. The MRI study included ASL and DWI. The ASL-derived cerebral blood flow (CBF) maps were coregistered on the DWI images. RH volume and DIV were calculated and compared. Patient NIHSS scores were also evaluated at admission, discharge, and after 1 and 6-month follow-up., Results: Twenty-two patients showed RH with CBF twice than baseline. In all 22 patients, RH overlaps with DWI infarcted area. No significant difference (P = .94) between RH volume and DIV was found (7.2 ± 9.6 and 9.0 ± 11.9 cm 3 ). The Pearson's correlation coefficient between RH and DIV was .93. On univariate analysis, a significant difference was found between patient's groups on NIHSS at any time points, after covariates adjustment NIHSS difference was significant only at admission., Conclusions: The study showed that ASL perfusion could be an integral part of the MRI examination in the assessment of 24-36 hours not-treated stroke patients as sustained RH group had improved outcomes. More importantly, ASL perfusion may provide evidence of beneficial effects of reperfusion induced by recanalization treatment., (© 2018 by the American Society of Neuroimaging.)

Background and Purpose: Transient ischemic attack may rarely reveal an intracranial artery occlusion. We analyzed acute magnetic resonance imaging (MRI) patterns and early outcome after reperfusion therapy in these cases., Method: Clinical and imaging data were taken retrospectively from our comprehensive stroke center registry. Two MRI patterns were determined. Pattern A: full mismatch with negative diffusion-weighted imaging (DWI) and perfusion defect. Pattern B: large mismatch with positive DWI and perfusion defect. MRI-derived collateral flow maps were automatically generated from the raw of dynamic susceptibility contrast MRI. Patients were treated either by recombinant tissue plasminogen activator (rtPA) alone or in combination with mechanical thrombectomy., Results: From October 1, 2010 to May 15, 2016, 1,019 patients were admitted and treated by t-PA within 4.5 hours of stroke onset of them; 14 had a transient ischemic attack (TIA) within the 6 hours preceding MRI. Perfusion imaging was performed in 11 patients. An arterial occlusion was found in all of them, 11 patients had a distal anterior circulation occlusion, whereas 3 patients (21%) had a proximal occlusion. According to MRI, 6 patients showed pattern A, whereas 5 patients had pattern B. Good collaterals were observed in 10 patients (6 patients with grade 3 and 4 patients with grade 4), whereas 1 patient had poor collaterals (grade 2). The day 1 National Institutes of Health Stroke Scale median was 0. Modified Rankin Scale median at 3 months was 0., Conclusion: TIAs may reveal acute intracranial artery occlusion. Acute MRI may able to assist in therapeutic decision., (© 2018 by the American Society of Neuroimaging.)