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Background and Purpose: The ‘lacunar hypothesis’ has been challenged, since small (diameter <15 mm) subcortical infarcts can be produced by middle cerebral artery disease (MCAD) or cardioembolism (CE), while a larger infarct can occur without evidence of MCAD or CE. We sought to assess whether the lacunar hypothesis based on size is still valid. Methods: We studied 118 patients who were admitted within 72 h after stroke onset and had acute deep subcortical MCA territory infarcts detected by diffusion-weighted MRI, and who had undergone angiography (mostly MR angiography). Stroke mechanisms were arbitrarily categorized regardless of lesion size: (1) MCAD when there was a corresponding MCA lesion; (2) internal carotid artery disease (ICAD) when there was a significant (>50%) ipsilateral ICAD; (3) CE when there was emboligenic heart disease without MCAD or ICAD, and (4) small vessel disease (SVD) when there was neither CE nor MCAD. SVD was further divided into definite SVD (dSVD, longest diameter <15 mm) or probable SVD (pSVD, longest diameter ≥15 mm). Results: Seventy-three patients (62%) had SVD, of which 38 (32%) had pSVD and 35 (30%) dSVD. Thirty-three patients (28%) had MCAD, five (4%) CE, and seven (6%) ICAD. The infarct diameter in MCAD was not larger than in SVD (p = 0.35), and there was no difference in clinical features or risk factors between MCAD and SVD, or between pSVD and dSVD. CE was distinguished from SVD by its larger size and cortical symptoms. Conclusions: There are no clinical and lesion-size differences between MCAD and SVD, suggesting that there seems to be no rationale for the 15 mm size criterion for lacunar or small-vessel infarction. Copyright © 2007 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Background: Posterior reversible encephalopathy syndrome (PRES) is characterized by cerebral blood flow dysregulation and the blood–brain barrier (BBB) disruption. While renal insufficiency has been considered a factor in BBB fragility, the relationship between renal insufficiency and the PRES lesions volume remains unclear. Methods: This observational study was performed retrospectively. PRES patients were categorized into two groups with renal insufficiency, defined as an estimated glomerular filtration rate (eGFR) of less than 60 mL/min/1.73m2 on the day of symptom occurrence. Lesion volume was measured using fluid-attenuated inversion recovery (FLAIR) imaging, and the brain was divided into nine regions. The volume of the parietal-occipital-temporal lobe was considered typical, while the other six regions were labeled as atypical. Results: The study included 200 patients, of whom 94 (47%) had renal insufficiency. Patients with renal insufficiency had a larger lesion volume (144.7 ± 125.2 cc) compared to those without renal insufficiency (110.5 ± 93.2 cc; p = 0.032); particularly in the atypical lesions volume (49.2 ± 65.0 vs. 29.2 ± 44.3 cc; p = 0.013). However, there was no difference in the reversibility of the lesions (35.2 ± 67.5 vs. 18.8 ± 33.4 cc; p = 0.129). Multiple regression analysis revealed that decreases in eGFR (β = -0.34, 95% CI -0.62-0.05, p = 0.020) were positively associated with total lesion volume. Conclusion: Our findings suggest that PRES patients with renal insufficiency experience more severe lesion volumes, likely due to the atypical brain regions involvement. The lesions involving atypical regions may have a similar pathophysiology to typical lesions, as the PRES lesions reversibility was found to be similar between individuals with and without renal insufficiency. [ABSTRACT FROM AUTHOR]

Discusses the case of diffusion-weighted imaging findings in brain stem hypertensive encephalopathy (HE). Neurologic examination; Results of the magnetic resonance imaging; Mechanisms which have been discussed with respect to the high signals in HE.

Abstract: Although stroke is a leading cause of disability, the quantitative relationship between baseline clinical and imaging characteristics and long‐term disability outcomes has rarely been studied. Prospectively collected clinical data from 405 patients with acute ischemic stroke including brain magnetic resonance images (MRIs) and disability outcomes assessed using the modified Rankin Scale (mRS) 3 month after the onset of disease were analyzed using a proportional odds cumulative logit model implemented in NONMEM. The relationship between the difference in lesion volume (DLV) — lesion volume measured by brain MRI 5 days later — lesion volume at the onset of the disease, and the mRS measured at 3 months (mRS3) was modeled first, and the potential covariates were tested. The Emax model best described the relationship between DLV and the logit probability of each mRS3. DLV, baseline stroke severity, age, and diabetes mellitus were identified as significant predictors of the probabilities of mRS3. The quantitative model constructed in the current analysis will enable us to predict the long‐term disabilities of the patients with acute ischemic stroke using the patient‐specific MRI and other clinical information, which will be useful for individualizing therapies and for making the clinical development of a novel drug more efficient. [ABSTRACT FROM AUTHOR]

Background: The stroke mechanism for anterolateral pontine infarction (ALPI) is poorly understood. We aimed to investigate the perforator arteries relevant to ALPI using highresolution MRI (HR-MRI). Methods: Of 62 patients with ALPI who were admitted to the Asan Medical Center, 13 patients agreed to participate in this study. We used HR-MRI with a 3-Tesla scanner and assessed the perforating branches directly connected with the infarcted area. Results: Perforating arteries penetrating ALPI were identified in all 13 patients. Perforators arising from the basilar artery (BA) were involved in the stroke mechanism in 9 patients, the superior cerebellar artery (SCA) perforator in 1 patient, and the anterior inferior cerebellar artery perforator in 1 patient. In 2 patients, both BA and SCA perforators were involved. Conclusions: Using 3-Tesla HR-MRI may allow visualization of the perforating branches presumably related to ALPI. Identification of the relevant cerebral perforating arteries may help us to understand the stroke mechanism in patients with posterior circulation territory infarction. [ABSTRACT FROM AUTHOR]

Background: Chronic refractory cough significantly impairs the psychological and social aspects of quality of life. Loss of inhibitory control is suggested as a potential central neurobiological mechanism underlying chronic refractory cough.Research Question: Do structural and functional changes related to chronic cough occur in higher cortical brain regions?Study Design and Methods: The structural and resting-state functional alterations in the brains of 15 patients with chronic refractory cough and 15 age- and sex-matched healthy control participants were evaluated. Gray matter volumes of the whole brain were measured using voxel-based morphometry based on T1-weighted MRI. Intrinsic functional connectivity within large-scale brain networks was examined on resting-state functional MRI. Correlation analyses were performed to examine the relationships of these brain changes with duration, severity, and impact of cough.Results: Compared with healthy control participants, patients with chronic refractory cough demonstrated a lower gray matter volume in the left frontal cluster and enhanced functional connectivity within the left frontoparietal network, which were associated with greater cough scores. Furthermore, enhanced functional connectivity within the left frontoparietal network was associated with a greater psychological and social impact of coughing. Lower left frontal gray matter volume was associated with longer cough duration.Interpretation: Structural and functional alterations in the left frontal brain regions may be implicated in the psychological and social impact and disease duration of chronic refractory cough. Our findings provide new perspectives on developing interventional approaches targeting the cognitive modulation of chronic coughing. [ABSTRACT FROM AUTHOR]

Objectives: To investigate whether clinical condition, imaging session, and locations affect repeatability of amide proton transfer-weighted (APTw) magnetic resonance imaging (MRI) in the brain.Materials and Methods: Three APTw MRI data sets were acquired, involving two intrasession scans and one intersession scan for 19 healthy, 15 glioma, and 12 acute stroke adult participants (mean age 53.8, 54.6, and 68.5, respectively) on a 3T MR scanner. The mean APTw signals from five locations in healthy brain (supratentorial and infratentorial locations) and from entire tumor and stroke lesions (supratentorial location) were calculated. The within-subject coefficient of variation (wCV) and intraclass correlation coefficient (ICC) were calculated for each clinical conditions, image sessions, and anatomic locations. Differences in APTw signals between sessions were analyzed using repeated-measures analysis of variance.Results: The ICC and wCV were 0.96 (95% confidence interval [CI], 0.91-0.99) and 16.1 (12.6-21.3) in glioma, 0.93 (0.82-0.98) and 15.0 (11.4-20.6) in stroke, and 0.84 (0.72-0.91) and 34.0 (28.7-41.0) in healthy brain. There were no significant differences in APTw signal between three sessions, irrespective of disease condition and location. The ICC and wCV were 0.85 (0.68-0.94) and 27.4 (21.8-35.6) in supratentorial, and 0.44 (- 0.18 to 0.76) and 32.7 (25.9 to 42.9) in infratentorial locations. There were significant differences in APTw signal between supra- (mean, 0.49%; 95% CI, 0.38-0.61) and infratentorial locations (1.09%, 0.98-1.20; p < 0.001).Conclusion: The repeatability of APTw signal was excellent in supratentorial locations, while it was poor in infratentorial locations due to severe B0 inhomogeneity and susceptibility which affects MTR asymmetry.Key Points: • In supratentorial locations, APTw MRI showed excellent intrasession and intersession repeatability in brains of healthy controls and patients with glioma, as well as in stroke-affected regions. • APTw MRI showed excellent repeatability in supratentorial locations, but poor repeatability in infratentorial locations. • Considering poor repeatability in the infratentorial locations, the use of APTw MRI in longitudinal assessment in infratentorial locations is not indicated. [ABSTRACT FROM AUTHOR]

Objectives: To determine whether fast scanned MRI using a 1.5-T scanner is a reliable method for the detection and characterization of acute ischemic stroke in comparison with conventional MRI.Methods: From May 2015 to June 2016, 862 patients (FLAIR, n = 482; GRE, n = 380; MRA, n = 190) were prospectively enrolled in the study, with informed consent and under institutional review board approval. The patients underwent both fast (EPI-FLAIR, ETL-FLAIR, TR-FLAIR, EPI-GRE, parallel-GRE, fast CE-MRA) and conventional MRI (FLAIR, GRE, time-of-flight MRA, fast CE-MRA). Two neuroradiologists independently assessed agreements in acute and chronic ischemic hyperintensity, hyperintense vessels (FLAIR), microbleeds, susceptibility vessel signs, hemorrhagic transformation (GRE), stenosis (MRA), and image quality (all MRI), between fast and conventional MRI. Agreements between fast and conventional MRI were evaluated by generalized estimating equations. Z-scores were used for comparisons of the percentage agreement among fast FLAIR sequences and fast GRE sequences and between conventional and fast MRA.Results: Agreements of more than 80% were achieved between fast and conventional MRI (ETL-FLAIR, 96%; TR-FLAIR, 97%; EPI-GRE, 96%; parallel-GRE, 98%; fast CE-MRA, 86%). ETL- and TR-FLAIR were significantly superior to EPI-FLAIR in the detection of acute ischemic hyperintensity and hyperintense vessels, while parallel-GRE was significantly superior to EPI-GRE in the detection of susceptibility vessel sign (p value < 0.05 for all). There were no significant differences in the other scores and image qualities (p value > 0.05).Conclusions: Fast MRI at 1.5 T is a reliable method for the detection and characterization of acute ischemic stroke in comparison with conventional MRI.Key Points: • Fast MRI at 1.5 T may achieve a high intermethod reliability in the detection and characterization of acute ischemic stroke with a reduction in scan time in comparison with conventional MRI. [ABSTRACT FROM AUTHOR]

Objectives: To compare three-dimensional high-resolution magnetic resonance imaging (3D HR-MRI) and digital subtraction angiography (DSA) for diagnosing and evaluating stenosis in the entire circle of Willis.Methods: The study included 516 intracranial arteries from 43 patients with intracranial artery stenosis (ICAS) who underwent both 3D HR-MRI and DSA within 1 month. Two readers independently diagnosed atherosclerosis, dissection, moyamoya disease and vasculitis, rated their diagnostic confidence for each vessel and measured the luminal diameters. Reference standard was made from clinico-radiologic diagnosis. Diagnostic accuracy, diagnostic confidence, the degree of stenosis and luminal diameter were assessed and compared between both modalities.Results: For atherosclerosis, 3D HR-MRI showed better diagnostic accuracy (P = .03-.003), sensitivity (P = .006-.01) and positive predictive value (P ≤ .001-.006) compared to DSA. Overall, the readers were more confident of their diagnosis of ICAS when using 3D HR-MRI (reader 1, P ≤ .001-.007; reader 2, P ≤ .001-.015). 3D HR-MRI showed similar degree of stenosis (P > .05) and higher luminal diameter (P < .05) compared to DSA.Conclusions: 3D HR-MRI might be useful to evaluate atherosclerosis, with better diagnostic confidence and comparable stenosis measurement compared to DSA in the entire circle of Willis.Key Points: • 3D HR-MRI showed better diagnostic accuracy for atherosclerosiscompared to DSA • 3D HR-MRI showed better overall diagnostic confidence for stenosiscompared to DSA • 3D HR-MRI and DSA showed similar degree of stenosis. [ABSTRACT FROM AUTHOR]

Background: Although high-resolution magnetic resonance imaging (HR-MRI) has been used as a strong imaging method for diagnosing intracranial vertebral artery dissection (IVAD), the diagnosis is sometimes challenging because a dissection has geometric changes in the natural course. The radiologic features may change or disappear over time, which makes the diagnosis confusing. Our study was to present radiological findings according to the stages in spontaneous and unruptured, IVAD on 3T HR-MRI and to guide the age estimation of IVAD with the distinguishing findings according to the stages. Methods: From January 2011 to July 2014, the 41 vertebral arteries (M:F = 18: 12; age range 32-67 years) were retrospectively enrolled. Spontaneous, unruptured IVAD was diagnosed if it had a clear onset based on clinical and radiological findings. The stages were classified as acute (0-3 days), early subacute (3-10 days), late subacute (10-60 days) and chronic stage (>60 days; recovery and nonrecovery groups) according to the time intervals from symptom onset, based on the prior published studies. HR-MR findings were assessed and compared in the intimal flap, double lumen, aneurysmal dilatation (maximal outer diameter, maximal wall thickness, wall thickness index and remodeling index), intramural hematoma (relative signal intensity) and vessel wall enhancement according to the stages with qualitative and quantitative methods. Two radiologists analyzed the HR-MR findings with consensus reading. Results: IVAD was classified into acute (n = 6), early subacute (n = 8), late subacute (n = 16) and chronic (n = 11) stages. HR-MR dissection findings such as intimal flap, double lumen, aneurysmal dilatation and intramural hematoma significantly decreased from the earlier stages to the chronic stage (p < 0.05). The quantitative indices in aneurysmal dilatation and the relative signal intensity of intramural hematoma showed significant higher values in the earlier stages followed by a significant decrease in the chronic stage recovery group (p < 0.05). The degree of vessel wall enhancement was higher in the earlier stage and decreased in the chronic stage (p < 0.05), but mild vessel wall enhancement was identified 900 days after symptom onset. Conclusion: The 3T HR-MRI reveals the vessel wall characteristics and provides distinguishing findings between earlier stages and the chronic stage in spontaneous and unruptured IVAD. Characterization of these radiological findings according to stages may assist with the age estimation of the dissection and may help to understand IVAD as a whole. [ABSTRACT FROM AUTHOR]

Background and purpose Although cervicocranial artery dissections (CADs) are common causes of ischemic stroke in young individuals, anatomical locations and mechanisms of ischemic strokes are still unclear. We evaluate the prevalence, location, and pathogenic mechanisms of ischemic stroke caused by CADs. Methods We reviewed CAD patients who presented with acute (< 7 days) ischemic events and who had undergone diffusion weighted magnetic resonance imaging (MRI) and appropriate vascular imagings (MR angiography, computed tomography angiography, digital subtraction angiography, and high-resolution MRI). Stroke mechanisms were categorized as artery-to-artery (AA) embolism, local branch occlusion, in situ thrombotic occlusion and hemodynamic impairment. Results One hundred and thirty-five patients with cerebral infarcts (n = 125) or transient ischemic attacks (n = 10) were included. The locations of 159 dissected vessels were: 77 vertebral, 29 internal carotid, 24 middle cerebral, 12 basilar, eight posterior inferior cerebellar, five anterior cerebral, and four posterior cerebral arteries. Among stroke mechanisms, A–A embolism (n = 70, 55.5%) was the most common followed by local branch occlusions (n = 40, 31.7%) and in situ thrombotic occlusions (n = 8, 6.3%). Intracranial CADs were more common (89 vs. 44), less often associated with trauma (21.3% vs. 40.9%, p = 0.018) and A–A embolism (32.9% vs. 97.6%, p < 0.001), and more often treated with intravenous thrombolysis (15.7% vs. 2.3%. p = 0.021) than extracranial CADs. Conclusions In our cohort, intracranial CADs are more common than extracranial CADs, and the vertebral artery is the most frequently involved site. Although A–A embolism is the main stroke mechanism, local branch occlusion is another important stroke mechanism. [ABSTRACT FROM AUTHOR]

Summary: Background: Many patients with stroke are precluded from thrombolysis treatment because the time from onset of their symptoms is unknown. We aimed to test whether a mismatch in visibility of an acute ischaemic lesion between diffusion-weighted MRI (DWI) and fluid-attenuated inversion recovery (FLAIR) MRI (DWI-FLAIR mismatch) can be used to detect patients within the recommended time window for thrombolysis. Methods: In this multicentre observational study, we analysed clinical and MRI data from patients presenting between Jan 1, 2001, and May 31, 2009, with acute stroke for whom DWI and FLAIR were done within 12 h of observed symptom onset. Two neurologists masked to clinical data judged the visibility of acute ischaemic lesions on DWI and FLAIR imaging, and DWI-FLAIR mismatch was diagnosed by consensus. We calculated predictive values of DWI-FLAIR mismatch for the identification of patients with symptom onset within 4·5 h and within 6 h and did multivariate regression analysis to identify potential confounding covariates. This study is registered with ClinicalTrials.gov, number NCT01021319. Findings: The final analysis included 543 patients. Mean age was 66·0 years (95% CI 64·7–67·3) and median National Institutes of Health Stroke Scale score was 8 (IQR 4–15). Acute ischaemic lesions were identified on DWI in 516 patients (95%) and on FLAIR in 271 patients (50%). Interobserver agreement for acute ischaemic lesion visibility on FLAIR imaging was moderate (κ=0·569, 95% CI 0·504–0·634). DWI-FLAIR mismatch identified patients within 4·5 h of symptom onset with 62% (95% CI 57–67) sensitivity, 78% (72–84) specificity, 83% (79–88) positive predictive value, and 54% (48–60) negative predictive value. Multivariate regression analysis identified a longer time to MRI (p<0·0001), a lower age (p=0·0009), and a larger DWI lesion volume (p=0·0226) as independent predictors of lesion visibility on FLAIR imaging. Interpretation: Patients with an acute ischaemic lesion detected with DWI but not with FLAIR imaging are likely to be within a time window for which thrombolysis is safe and effective. These findings lend support to the use of DWI-FLAIR mismatch for selection of patients in a future randomised trial of thrombolysis in patients with unknown time of symptom onset. Funding: Else Kröner-Fresenius-Stiftung, National Institutes of Health. [Copyright &y& Elsevier]

Abstract: Background and purpose: Although MRI may provide much information on brain pathology to aid in patient selection for thrombolysis, the concern remains that MRI screening may increase time-to-treatment. We hypothesized that CT-plus-MRI screening might be a valuable time-efficient alternative for selection of patients requiring thrombolysis. Methods: We reviewed acute stroke patients who received intravenous tissue plasminogen activator (tPA) (with or without intra-arterial urokinase) initiated within 3h of stroke between March 2004 and March 2007. MRI was the routine screening imaging employed until November 2005. Thereafter, CT-plus-MRI screening was performed; tPA of 0.6mg/kg was infused intravenously after exclusion of hemorrhage by CT screening, and subsequently a further decision on thrombolysis (i.e., intravenous tPA of 0.3mg/kg, or intra-arterial urokinase) was made after MRI screening. We compared times-to-treatment and clinical outcomes between MRI screening and CT-plus-MRI-screening groups, and identified factors associated with good clinical outcome (modified Rankin Scale ≤2 at 3months). Results: Eighty-nine patients were included in the analysis; 43 were MRI-screened, and 46 were CT-plus-MRI-screened. Although the MRI-screening group had a longer door-to-needle time (p <0.001), these patients showed better 3-month outcomes compared to CT-plus-MRI-screening group (p =0.01). Multivariate analysis showed that MRI screening (odds ratio 3.97, 95% confidence interval 1.30–12.17, p =0.02) was independently associated with a good outcome at 3months. In CT-plus-MRI-screening group, although time-to-initial imaging and time-to-tPA were shorter, time-to-MRI and time-to-additional thrombolysis were delayed. Conclusion: These results suggest that early patient selection using MRI may be more effective than reduction of times-to-treatment in improvement of thrombolytic outcomes. [Copyright &y& Elsevier]

Background: The effect of biochemical aspirin resistance (BAR) on ischemic stroke has not been well established. Early recurrent ischemic lesions (ERILs) on diffusion-weighted imaging (DWI) are proposed as potential surrogate markers of clinically recurrent stroke. Methods: We included 117 consecutive patients who (1) were admitted within 24 h of symptom onset; (2) had an ischemic stroke confirmed by DWI; (3) underwent follow-up DWI within seven days after onset, and (4) received aspirin treatment. BAR was measured using the VerifyNow® Aspirin Assay. We analyzed the associations between BAR and any ERILs (overall ERILs), and between BAR and ERILs occurring outside the vascular territories of index stroke (distant ERILs). Results: BAR was observed in 16 (13.7%) patients. Overall ERILs were detected in 34 (29.1%), and distant ERILs in 10 (8.5%) patients. Patients with BAR were more likely to develop ERILs, but the association was not significant (OR 2.13; 95% CI 0.72–6.29; p = 0.234). However, BAR was independently related to distant ERILs by logistic regression analysis (OR 6.01; 95% CI 1.29–28.09; p = 0.023). Conclusions: BAR was associated with distant ERILs but not with overall ERILs during the first week after ischemic stroke. Copyright © 2010 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Abstract: Background: An acute perfusion–diffusion mismatch is known to be the strongest predictor of infarct growth. However, the differential patterns of clinical and radiological evolution according to stroke mechanism are unknown. Methods: The study retrospectively reviewed consecutive patients who had 1) acute middle cerebral artery (MCA) territory infarction, 2) diffusion- and perfusion-weighted imaging (DWI and PWI) and MR angiography within 24 h of onset, and follow-up DWI 5 days later, 3) stenosis (≥50%) or occlusion of MCA on baseline imaging, 4) a baseline PWI–DWI mismatch >20%, and 5) either atherosclerotic MCA disease (MCAD) or cardioembolism (CE). National Institutes of Health Stroke Scale (NIHSS) scores and infarct volume at baseline and 5 days were obtained. Results: Of 90 patients, 52 had MCAD and 38 had CE. At baseline, CE group had more severe stroke (median NIHSS, 9 vs. 5; p =0.001) and larger infarct volume (median 8.32 cc vs. 3.0 cc; p =0.034) than MCAD group. During the 1-week period, CE group had larger infarct volume growth (median 12.85 cc vs. 3.02 cc; p =0.004) than MCAD group, although clinical improvement based on NIHSS (baseline minus 5-day) tended to be higher for CE than MCAD group (median 3 vs. 1; p =0.08). The correlation between infarct volume and NIHSS score was stronger in CE (r =0.841) compared to MCAD (r =0.582) group at 5-day. Conclusions: Substantial differences in the clinico-radiological evolution of acute ischemic stroke exist according to stroke mechanism. These data emphasize the importance of the stroke mechanism in the design of MRI-based acute stroke trials. [Copyright &y& Elsevier]