Initial Diffusion-weighted Imaging Lesion Research Articles

Delayed Lesions on Diffusion-Weighted Imaging in Initially Lesion-Negative Stroke Patients.

Background and Purpose Lesions on diffusion-weighted imaging (DWI) occasionally appear on follow-up magnetic resonance imaging (MRI) among initially DWI-negative but clinically suspicious stroke patients. We established the prevalence of positive conversion in DWI-negative stroke and determined the clinical factors associated with it. Methods This retrospective, observational, single-center study included 5,271 patients hospitalized due to stroke/transient ischemic attack (TIA) in a single university hospital during 2010 to 2017. Patients without initial DWI lesions underwent follow-up DWI imaging as a routine practice. Adjusted hazard ratios (aHRs) for recurrent stroke risk according to positive conversion were determined using Cox proportional hazard regression. Adjusted odds ratios (aORs) and 95% confidence intervals (CIs) for positive conversion among initially DWI-negative patients were estimated. Results In total, 694 (13.2%) patients (mean±standard deviation age, 62.9±13.7 years; male, 404 [58.2%]) were initially DWI-negative. Among them, 22.5% had positive-conversion on follow-up DWI. Positive conversion was associated with a higher risk of recurrent stroke (aHR, 3.12; 95% CI, 1.56 to 6.26). Early neurologic deterioration (aOR, 15.1; 95% CI, 5.71 to 47.66), atrial fibrillation (aOR, 6.17; 95% CI, 3.23 to 12.01), smoking (aOR, 3.76; 95% CI, 2.19 to 6.63), pre-stroke dependency (aOR, 1.62; 95% CI, 1.15 to 2.27), objective hemiparesis (aOR, 4.39; 95% CI, 1.90 to 10.32), longer symptom duration (aOR, 2.17; 95% CI, 1.57 to 3.08), high cholesterol (aOR, 4.70; 95% CI, 1.78 to 12.77), National Institutes of Health Stroke Scale score (aOR, 1.44; 95% CI, 1.08 to 1.91), and high systolic blood pressure (aOR, 1.01; 95% CI, 1.00 to 1.02) were associated with a higher incidence of lesions with delayed appearance. Regarding the location of lesions on follow-up DWI, 34.6% and 21.2% were in the cortex and brainstem, respectively. Conclusions In DWI-negative stroke/TIA, positive conversion is associated with a higher risk of recurrent stroke. DWI-negative stroke with factors related to positive conversion may require follow-up MRI for a definitive diagnosis.

Small cortical grey matter lesions show no persistent infarction in transient ischaemic attack? A prospective cohort study

ObjectivesTo find determining factors for persistent infarction signs in patients with transient ischaemic attack (TIA), herein initial diffusion lesion size, visibility on apparent diffusion coefficient (ADC) or fluid-attenuated inversion recovery...

Executive Function Declines in the First 6 Months After a Transient Ischemic Attack or Transient Neurological Attack

Although by definition transient, both transient ischemic attack (TIA) and transient neurological attack (TNA) are associated with cognitive impairment. Determinants and course of cognitive function afterward are, however, unclear. We prospectively determined cognitive performance after TIA and TNA in relation to clinical diagnosis and diffusion-weighted imaging (DWI) results. TIA and TNA patients aged ≥45 years without prior stroke or dementia underwent comprehensive cognitive assessment and magnetic resonance imaging within 7 days after the qualifying event. Cognitive tests were repeated after 6 months. Domain-specific compound z scores based on the baseline mean and SD were calculated. Repeated-measures analysis was used to test for differences in domain-specific cognitive performance over time between DWI-positive and DWI-negative patients, as well as between TIA and TNA patients. One hundred twenty-one patients were included (mean age (SD), 64.6 years (9.2 years), 60% TIA and 40% TNA) of whom 32 (26%) had a DWI lesion. Executive function performance decreased over time (mean change in compound score -0.23; P=0.01 adjusted for age, sex, education), whereas attention improved (0.11; P=0.02), and information processing speed and episodic memory remained unchanged. Patients with a DWI lesion had worse executive function at baseline than those without a DWI lesion (compound scores -0.26 versus 0.08; P=0.048), which persisted throughout the study period (P=0.04). Clinical diagnosis (TIA or TNA) was not related to cognitive function over time. Executive function declines during the first 6 months after TIA or TNA. Patients with an initial DWI lesion have persisting worse executive function than those without.

Abstract WP60: Evaluation of Tissue Reversibility by Relative Apparent Diffusion Coefficient Value in Acute Ischemic Stroke Patients Treated With Successful Thrombectomy

Background: By recent advance of endovascular thrombectomy, we have often experienced acute ischemic patients who have diffusion weighted imaging (DWI) reversal lesions after earlier successful recanalization. We retrospectively investigated the relationship between apparent diffusion coefficient (ADC) thresholds of tissue infarction and time from onset to recanalization in acute ischemic stroke patients. Methods: We assessed 24 patients who have occlusion of internal carotid artery (n=11) and the main trunk of middle cerebral artery (n=13) and obtained recanalization of TICI2b (n=12) and TICI3 (n=12) by thrombectomy and performed MRI before and after treatment. Relative ADC (rADC) value were calculated for initial DWI lesions and around hypoperfused regions. We evaluated rADC values in infarcted and non-infarcted area and analyzed the relationship between rADC thresholds of tissue infarction and time. Results: The mean time from onset to recanalization was 209 minutes and mean initial NIHSS was 15.4. The mean rADC value was 0.633 in infarcted lesions and 0.905 in non-infarcted area (p<0.001). The thresholds for rADC value for infarction by the area under the curve derived from receiver operating characteristic curve analysis were 0.769 in the area which recanalized under 180 minutes form the onset, 0.792 in that from 180 to 240 minutes, and 0.798 in that over 240 minutes. Conclusion: The estimation of rADC value may be useful in predicting the likelihood of DWI lesion reversal. Marked decreasing of rADC value which is under thresholds of infarction indicated irreversible damage of ischemic tissue regardless of early successful recanalization.

Subjective Cognitive Impairment, Depressive Symptoms, and Fatigue after a TIA or Transient Neurological Attack: A Prospective Study.

Introduction Subjective cognitive impairment (SCI), depressive symptoms, and fatigue are common after stroke and are associated with reduced quality of life. We prospectively investigated their prevalence and course after a transient ischemic attack (TIA) or nonfocal transient neurological attack (TNA) and the association with diffusion-weighted imaging (DWI) lesions. Methods The Cognitive Failures Questionnaire, Hospital Anxiety and Depression Scale, and Subjective Fatigue subscale from the Checklist Individual Strength were used to assess subjective complaints shortly after TIA or TNA and six months later. With repeated measure analysis, the associations between DWI lesion presence or clinical diagnosis (TIA or TNA) and subjective complaints over time were determined. Results We included 103 patients (28 DWI positive). At baseline, SCI and fatigue were less severe in DWI positive than in DWI negative patients, whereas at follow-up, there were no differences. SCI (p = 0.02) and fatigue (p = 0.01) increased in severity only in DWI positive patients. There were no differences between TIA and TNA. Conclusions Subjective complaints are highly prevalent in TIA and TNA patients. The short-term prognosis is not different between DWI-positive and DWI negative patients, but SCI and fatigue increase in severity within six months after the event when an initial DWI lesion is present.

Role of Perfusion-Weighted Imaging in a Diffusion-Weighted-Imaging-Negative Transient Ischemic Attack.

Background and PurposeThe absence of acute ischemic lesions in diffusion-weighted imaging (DWI) in transient ischemic attack (TIA) patients makes it difficult to diagnose the true vascular etiologies. Among patients with DWI-negative TIA, we investigated whether the presence of a perfusion-weighted imaging (PWI) abnormality implied a true vascular event by identifying new acute ischemic lesions in follow-up magnetic resonance imaging (MRI) in areas corresponding to the initial PWI abnormality.MethodsThe included patients underwent DWI and PWI within 72 hours of TIA and also follow-up DWI at 3 days after the initial MRI. These patients had visited the emergency room between July 2009 and May 2015. Patients who demonstrated initial DWI lesions were excluded. The initial PWI abnormalities in the corresponding vascular territory were visually classified into three patterns: no abnormality, focal abnormality, and territorial abnormality.ResultsNo DWI lesions were evident in initial MRI in 345 of the 443 TIA patients. Follow-up DWI was applied to 87 of these 345 DWI-negative TIA patients. Initial PWI abnormalities were significantly associated with follow-up DWI abnormalities: 8 of 43 patients with no PWI abnormalities (18.6%) had new ischemic lesions, whereas 13 of 16 patients with focal perfusion abnormalities (81.2%) had new ischemic lesions in the areas of initial PWI abnormalities [odds ratio (OR)=15.1, 95% confidence interval (CI)=3.6–62.9], and 14 of 28 patients with territorial perfusion abnormalities (50%) had new lesions (OR=3.7, 95% CI=1.2–11.5).ConclusionsPWI is useful in defining whether or not the transient neurological symptoms in DWI-negative TIA are true vascular events, and will help to improve the understanding of the pathomechanism of TIA.

MRI Assessment of Ischemic Lesion Evolution within White and Gray Matter

Background: In acute ischemic stroke (AIS), gray matter (GM) and white matter (WM) have different vulnerabilities to ischemia. Thus, we compared the evolution of ischemic lesions within WM and GM using MRI. Methods: From a European multicenter prospective database (I-KNOW), available T1-weighted images were identified for 50 patients presenting with an anterior AIS and a perfusion weighted imaging (PWI)/diffusion weighted imaging (DWI) mismatch ratio of 1.2 or more. Six lesion compartments were outlined: initial DWI (b = 1,000 s/mm²) lesion, initial PWI-DWI mismatch (T_max >4 s and DWI-negative), final infarct mapped on 1-month fluid-attenuated inversion recovery (FLAIR) imaging, lesion growth between acute DWI and 1-month FLAIR, DWI lesion reversal at 1 month and salvaged mismatch. The WM and GM were segmented on T1-weighted images, and all images were co-registered within subjects to the baseline MRI. WM and GM proportions were calculated for each compartment. Results: Fifty patients were eligible for the study. Median delay between symptom onset and baseline MRI was 140 min. The percentage of WM was significantly greater in the following compartments: initial mismatch (52.5 vs. 47.5%, p = 0.003), final infarct (56.7 vs. 43.3%, p < 0.001) and lesion growth (58.9 vs. 41.2%, p < 0.001). No significant difference was found between GM and WM percentages within the initial DWI lesion, DWI reversal and salvaged mismatch compartments. Conclusions: Ischemic lesions may extend preferentially within the WM. Specific therapeutic strategies targeting WM ischemic processes may deserve further investigation.

PP.34.20

Objective: Cerebral ischemic lesion volume determined by diffusion-weighted imaging (DWI) may be predictive of clinical severity and has been used as a surrogate of clinical outcome. We aimed to study the role of blood pressure-derived measurements for the prediction of lesion evolution in acute stroke patients. Design and method: We conducted a prospective study of 28 patients (aged 58.2 ± 13.5, 23 men) with sudden onset of ischemic stroke during the last 24 hours. DWI was performed immediately at admission (< 24 hours from symptoms onset) and on day 5. Blood pressure (BP) monitoring (SpaceLabs 90207) was performed on day 5 after symptoms onset. We used the difference of DWI lesion volumes between day 5 and day 1 (D5-D1) as an index of stroke lesion growth and standard deviation of blood pressure (BP-SD) as a measure of BP variability. Data were analysed using linear regression. Results: DWI lesion volume was significantly higher on day 5 than initial DWI lesion (35.8 ± 78.7 vs 22.1 ± 62.8 mL, p = 0.003). In univariate analysis, stroke lesion growth (D5-D1) was associated with SBP-SD and DBP-SD, but not with SBP nor DBP (Table). In multivariate analysis, only SBP-SD remained significantly associated with stroke lesion growth, after adjustment for age, sex, administration of rt-PA and SBP or MBP (Table).*SBP and DBP are adjusted for age, sex and administration of rt-PA; SBP-SD and DBP-SD are adjusted for age, sex, administration of rt-PA and SBP or DBP, respectively. Conclusions: Our data suggest that blood pressure variability appears to be independently associated with stroke lesion growth. BP-derived indices seem to be valuable in early estimation of prognosis of stroke patients.

Abstract T P36: DWI Lesion Size but Not FLAIR Status Alone is Associated With Early Clinical Outcome in Stroke Patients Undergoing MRI Prior to Systemic Thrombolysis

Objectives: Treatment of ischemic stroke holds the risk of intracerebral hemorrhage (ICH) due to systemic thrombolysis, often associated with poor functional outcome. Hence, parameters allowing prediction from deleterious courses are of increasing interest. We have recently shown that fluid-attenuated inversion recovery (FLAIR)-positive lesions seen on baseline magnetic resonance imaging (MRI) are associated with an increased rate on ICH. This study asked for the relationship between findings originating from baseline MRI and the clinical course. Methods: Using a multi-parameter hospital-based registry, the diffusion-weighted imaging (DWI) and FLAIR on baseline MRI of 122 ischemic stroke patients were analyzed for DWI lesion size and FLAIR-positive lesions within diffusion-restricted areas. These data originated from MRI that had been done prior to treatment with tissue plasminogen activator (tPA) within 3 hours from symptom onset, whereas computed tomography performed within 24 hours post-treatment served for detection of ICH. The early clinical outcome was assessed at hospital discharge using Barthel index (BI), modified Rankin scale (mRS) and National Institutes of Health Stroke Scale (NIHSS). Results: Out of 97 patients providing sufficient imaging quality, FLAIR-positive lesions were present in 25 patients (25.8 %) and ICH occurred in 32 patients (33.0 %). Remarkably, patients with or without FLAIR-positive lesions did not differ concerning the clinical outcome (BI, P =0.055; mRS, P =0.106; NIHSS, P =0.295). Patients exhibiting an initial DWI lesion size of at least 1/3 of vascular territory demonstrated an increased NIHSS ( P =0.031), increased mRS ( P =0.011) and decreased BI ( P =0.004) when compared to patients with smaller lesion sizes. As expected, more severe clinical affection was found in patients suffering from ICH (BI, P =0.013; mRS, P =0.001; NIHSS, P =0.016). Conclusions: In ischemic stroke patients treated with tPA, initial DWI lesion size was found to be closely associated with early clinical outcome, which was, however, not seen for FLAIR positivity. Therefore, a combination of both DWI lesion size and FLAIR status might represent an addition tool to enhance safety for stroke patients undergoing systemic thrombolysis.

The value of diffusion-weighted imaging in prediction of outcome of transient ischemic attacks

Objective The aim of the study was to study the clinical significance of diffusion-MRI in the prediction of outcome of transient ischemic attacks (TIAs) and its relation to the risk factors and TIA clinical presentations. Background Diffusion-weighted imaging (DWI) observations in TIA patients led to the proposal for a new definition of TIA, which is called the 'tissue-based' TIA definition, so that patients with clinical symptoms of focal brain with acute DWI-lesions, irrespective of the neurological signs duration, had a stroke rather than TIA. Patients and methods The participants in this study were classified into two groups: patient group (group I) and control group (group II) ( n = 20) of normal individuals. The patients in group I ( n = 35) were those who had had recent TIAs for the first time for whom an initial brain DWI was performed within 48 h after the onset of TIA and a follow-up one 3 months later for those with initial positive DWI. Results Initial DWI lesions were detected in nine (25.7%) patients; it was found that those with TIA duration 1 h or more, with mainly AF or carotid artery stenosis more than 50% and presenting clinically with aphasia or motor manifestations, had lesions on DWI. Conclusion TIA patients with duration of symptoms 1 h or more, atrial fibrillation or carotid artery stenosis more than 50% risk factors, and presenting clinically with motor deficits or aphasia had DWI positivity and thus an increased risk of developing stroke.

Diagnostic and Prognostic Value of Multimodal MRI in Transient Ischemic Attack

The clinical diagnosis of transient ischemic attack is highly subjective, and the risk prediction after transient ischemic attack using the clinical parameters still remains unsatisfactory. We aimed to investigate the diagnostic and prognostic value of multimodal magnetic resonance imaging in transient ischemic attack patients. We prospectively performed diffusion-weighted imaging, perfusion-weighted imaging, and intracranial and extracranial magnetic resonance angiogram within 72 h of symptom onset in 162 transient ischemic attack patients defined by the classical time-based definition. Follow-up diffusion-weighted imaging was obtained three-days later in patients who did not exhibit lesions on the initial diffusion-weighted imaging. The occurrence of clinical events (transient ischemic attack or stroke) three-months after the initial transient ischemic attack was recorded, and the ABCD2 and ABCD3-I scores were calculated. The clinical and imaging parameters were compared between patients with and without initial diffusion-weighted imaging lesion, clinical events, and follow-up diffusion-weighted imaging lesions. Abnormalities were present on diffusion-weighted imaging, perfusion-weighted imaging, and magnetic resonance angiogram in 38·9%, 44·1%, and 51·9% of patients, respectively. Diffusion-weighted imaging plus perfusion-weighted imaging explained 64·8%, and the addition of magnetic resonance angiogram explained 74% of the transient ischemic attack symptoms. The initial diffusion-weighted imaging positivity was associated with longer time from symptom onset to magnetic resonance imaging examination (odds ratio, 1·039; 95% confidence interval, 1·008-1·071; P=0·013). On follow-up diffusion-weighted imaging, new lesions were found in 46·7% of the patients who initially showed normal diffusion-weighted imaging findings. Initial perfusion-weighted imaging abnormality predicted the appearance of follow-up diffusion-weighted imaging lesion (chi-square=7·774, P=0·005). During the three-months follow-up, 23 patients (14·2%) experienced subsequent transient ischemic attack (n=16) or stroke (n=7). Symptomatic magnetic resonance angiogram abnormality (odds ratio, 12·667; 95% confidence interval, 2·859-56·110; P=0·001) was the only independent factor associated with clinical events with a sensitivity of 91·3% and specificity of 54·7% (C statistics, 0·73). None with initially normal multimodal magnetic resonance imaging findings developed subsequent clinical events. Approximately three-quarter of transient ischemic attack is associated with multimodal magnetic resonance imaging abnormality. Initial perfusion-weighted imaging abnormality predicts newly developed diffusion-weighted imaging lesions, and symptomatic magnetic resonance angiogram abnormality seems to be the most important predictor for subsequent clinical events. Multimodal magnetic resonance imaging appears to be useful in assessing transient ischemic attack and predicting outcome in these patients.

Frequency of emerging positive diffusion-weighted imaging in early repeat examinations at least 24 h after transient ischemic attacks

The relationships between diffusion lesions and risk scores for patients with a Transient ischemic attack (TIA) and the optimal timing for diffusion lesion screening have not been characterized. The purpose of our study was to evaluate the appearance of diffusion-weighted imaging (DWI) lesions during follow-up examinations of patients with TIA or minor stroke without initial DWI lesions. We identified 31 patients who did not show diffusion lesions in initial DWI. A second magnetic resonance imaging (MRI) examination was performed 24 h after the initial MRI, and the patients were divided into two groups based on the results. Demographic and clinical data, including initial National Institutes of Health Stroke Scale scores, ABCD and ABCD(2) scores, and other MRI findings were evaluated. The data were analyzed using Spearman's rank tests and unpaired t tests. Ten patients (32.3 %) showed diffusion lesions on the second DWI examination. Both risk scores were higher in these patients compared with patients with negative results on follow-up DWI (P < 0.05, unpaired t test) and correlated with the length of the TIA (R s = 0.017, P < 0.05; R s = 0.003, P < 0.01; Spearman's rank test). Our results suggest that TIA patients with high-risk scores might be underestimated if the first MRI was performed within 24 h of symptom onset.

Abstract 3467: Disappearance Of The Acute Diffusion Weighted Imaging Lesion After Treatment With tPA

Background: MRI with diffusion weighted imaging (DWI) is significantly more sensitive than head CT in the determination of acute ischemic stroke. In patients presenting with acute ischemic cerebrovascular syndrome (AICS), we sought to determine the probability of finding a normal DWI post treatment with tPA, despite a clinical syndrome and pretreatment MRI consistent with acute ischemia. While previous studies report a rate of stroke mimic (SM) of 3 to 10%, a more recent report estimates up to 21% of patients treated based on head CT were either stroke mimic or neuroimaging negative cerebral ischemia. Methods: We queried the LESION database for patients who presented with clinical syndrome consistent with AICS, underwent acute MRI screening and then underwent follow-up MRI at either 2hrs or 24hrs post treatment with iv-tPA. Experienced Stroke neurologist interpreted the follow up scans and identified those with absence of the initial DWI lesion. We excluded patients whose TOAST was small vessel disease or those with brainstem infarcts, given the higher incidence of false negative MRI in these types of stroke. Results: There were 195 patients who met inclusion criteria. Of these there were a total of 4 patients in whom early follow up imaging failed to reveal the previously seen DWI lesion for which they were treated. This represents 2.0% of patients. The causative lesion did reappear on subsequent imaging in 2 out of the 4 patients. In an additional 6 patients, the initial MRI was negative prior to treatment with none of these patients developing a DWI lesion post iv-tPA. Four of the six patients were determined to be stroke mimics after their work-up was completed. Conclusions: We found that 2.0% of patients with positive DWI prior to iv-tPA had follow-up imaging that failed to show the initial DWI lesion. In addition, 2.7% of patients treated had negative pre and post tPA imaging. We conclude that the true incidence of neuroimaging negative stroke post iv-tPA is unlikely to be greater than 5% in those patients screened with MRI. While the pathophysiological basis is not yet know, the transient disappearance of the DWI lesion may give rise to a higher rate of patients being interpreted as stroke mimics in those initially screened with head CT.

Isolated lateral thalamic infarction: the role of posterior cerebral artery disease

Lateral thalamic infarction (LTI) is usually caused by small vessel disease (SVD), i.e., occlusion of the deep perforator. However, focal atherosclerotic posterior cerebral artery disease (PCAD) may produce LTI via thrombotic occlusion of the perforator. We aimed to investigate the prevalence of PCAD in LTI and differences in clinical and imaging findings between LTIs associated with PCAD and SVD. We retrospectively evaluated 58 consecutive patients with isolated LTI who underwent diffusion-weighted imaging (DWI) and MR angiography (MRA) within 7 days after stroke onset. Patients were divided into two groups: those with PCAD and those with SVD. Clinical syndromes were divided into pure sensory stroke (PSS) and sensory stroke plus (SS-plus), i.e., the concomitant presence of motor dysfunction or ataxia. Clinical and imaging findings were compared between these two groups. Of the 58 patients, 13 (22.4%) had PCAD. PSS was more frequently associated with SVD than with PCAD (57.8% vs. 23.1%, P=0.032). Initial DWI lesion volume (cm³) was significantly larger in PCAD than in patients with SVD (0.38±0.13 vs. 0.33±0.22, P=0.025). Among the 23 patients (39.7%) who underwent follow-up DWI, patients with PCAD showed a significantly greater increase in subacute lesion volume than those with SVD (P=0.019). Although National Institutes of Health Stroke Scale scores did not differ at admission (P=0.185), they were significantly higher at discharge in PCAD than in patients with SVD (P=0.012). Our data suggest that PCAD is an important cause of LTI, being related to SS-plus, larger lesion volume, and worse clinical outcomes.

Failed Recovery from Thrombolysis Is Predicted by the Initial Diffusion Weighted Imaging Lesion

Background: The clinical response to systemic thrombolysis with recombinant tissue plasminogen activator (rtPA) is thought to depend on an early recanalization. We sought to investigate the effect of early recanalization on stroke lesion development as assessed with magnetic resonance imaging (MRI). Methods: Thirty-seven consecutive stroke patients (66 ± 13 years) treated with systemic thrombolysis with rtPA and tirofiban were grouped according to successful or failed recanalization as assessed on angiographic imaging. Infarct lesions were determined volumetrically in MRI prior to treatment and after 4 days. Results: Patients were severely affected (median National Institutes of Health Stroke Scale 14) and had significantly larger perfusion (PWI) than diffusion weighted imaging (DWI) lesion volumes. Ten patients with failed recanalization of the internal carotid or the middle cerebral artery did not improve. Their PWI and DWI lesion volumes were larger and the apparent diffusion coefficient more depressed than in the 27 patients with significant improvement and successful recanalization (p < 0.001). The DWI lesion volumes increased profoundly in the patients with failed recanalization (p < 0.001) but only little in the patients with successful recanalization. Multivariate regression analysis showed a relation of the initial DWI lesion volumes to the DWI lesion volumes at follow-up and the neurological recovery. Conclusions: The ischemic brain damage was particularly severe in patients with no recanalization already before systemic thrombolysis and predicted further lesion growth and failed recovery.

Internal Border Zone Lesions as a Predictor of Early Neurological Deterioration in Minor Stroke Patients with Severe Arterial Steno-Occlusion

Early neurological deterioration (END) of acute ischemic stroke may be important because it can predict clinical outcomes. We described several cases with similar clinical findings but different outcomes and analyzed the characteristics of their imaging studies. We retrospectively analyzed minor stroke patients with severe arterial stenosis within 6 hours of stroke onset. We defined END as 4 or more deterioration of the National Institutes of Health Stroke Scale score. Diffusion-weighted imaging (DWI) lesions were classified as lesions of the pial artery (PI), perforating artery (PAI) and border-zone (BZ). We consecutively analyzed a total of 12 subjects in this study. The patterns of initial DWI lesions were internal BZ (50%), PI (50%), PAI (25%), and cortical BZ (16.7%). Among them, the number of subjects with END was 5, and the frequency of internal BZ on initial DWI was significantly higher in patients with END than in those without. In conclusion, the results of this study suggest that when internal BZ infarcts are detected in patients with acute minor strokes accompanied by severe arterial stenosis, close observation and careful management should be performed because END can be induced at an early stage.

Prediction of malignant middle cerebral artery infarction by magnetic resonance imaging within 6 hours of symptom onset: A prospective multicenter observational study

Early identification of patients at risk of space-occupying "malignant" middle cerebral artery (MCA) infarction (MMI) is needed to enable timely decision for potentially life-saving treatment such as decompressive hemicraniectomy. We tested the hypothesis that acute stroke magnetic resonance imaging (MRI) predicts MMI within 6 hours of stroke onset. In a prospective, multicenter, observational cohort study patients with acute ischemic stroke and MCA main stem occlusion were studied by MRI including diffusion-weighted imaging (DWI), perfusion imaging (PI), and MR-angiography within 6 hours of symptom onset. Multivariate regression analysis was used to identify clinical and imaging predictors of MMI. Of 140 patients included, 27 (19.3%) developed MMI. The following parameters were identified as independent predictors of MMI: larger acute DWI lesion volume (per 1 ml odds ratio [OR] 1.04, 95% confidence interval [CI] 1.02-1.06; p < 0.001), combined MCA + internal carotid artery occlusion (5.38, 1.55-18.68; p = 0.008), and severity of neurological deficit on admission assessed by the National Institutes of Health Stroke Scale score (per 1 point 1.16, 1.00-1.35; p = 0.053). The prespecified threshold of a DWI lesion volume >82 ml predicted MMI with high specificity (0.98, 95% CI 0.94-1.00), negative predictive value (0.90, 0.83-0.94), and positive predictive value (0.88, 0.62-0.98), but sensitivity was low (0.52, 0.32-0.71). Stroke MRI on admission predicts malignant course in severe MCA stroke with high positive and negative predictive value and may help in guiding treatment decisions, such as decompressive surgery. In a subset of patients with small initial DWI lesion volumes, repeated diagnostic tests are required.

Stunned brain syndrome: serial diffusion perfusion MRI of delayed recovery following revascularisation for acute ischaemic stroke

BackgroundClinical response immediately after revascularisation therapy differs among patients. Although reperfusion is the deciding factor with respect to this dramatic response to revascularisation therapy, the influence of pre- and post-treatment...

Differential Pathophysiological Mechanisms of Stroke Evolution between New Lesions and Lesion Growth: Perfusion-Weighted Imaging Study

Background: Stroke evolution frequently occurs during the first week after stroke. However, the association between the type of stroke evolution and baseline perfusion severity has not been investigated. Methods: We analyzed clinical and serial MRI data on patients with acute middle cerebral artery infarcts. Multimodal MRIs were acquired before treatment and on day 7. Time to peak (T_max) perfusion lesion maps were then generated, and changes in the day 7 diffusion-weighted imaging (DWI) were classified; new lesions were defined as new DWI lesions not contiguous with initial abnormalities, and infarct growth as enlargement of DWI lesions. Results: Among 74 patients (mean age 64.2 years), 51 received recanalization therapy. The day 7 DWI revealed the presence of new lesions in 39 cases (52.7%) and infarct growth (mean ± SD 20.0 ± 4.3 ml) in 52. No correlation was observed between new lesion and infarct growth (r = 0.029, p = 0.805). Most new lesions were multiple and small, located in cortical/superficial areas and within the mild perfusion delay (2 ≤ T_max < 4 s) regions, whereas infarct growth generally occurred within the severer perfusion delay regions. Multiple regression analysis revealed that large mild perfusion delay was independently associated with new lesions, whereas large initial DWI lesions and a severer perfusion delay (4 ≤ T_max < 8 s) were associated with infarct growth. In terms of treatment, endovascular therapy was associated with new lesions, whereas the degree of angiographic recanalization was inversely associated with infarct growth. Conclusions: The types of stroke evolution differed depending on the baseline hypoperfusion severity, and the mode and effect of recanalization therapy. A poor correlation was observed between new lesions and infarct growth.

Risk of Symptomatic Intracerebral Hemorrhage in Patients Treated with Intra-Arterial Thrombolysis

Background: In intra-arterial (IA) thrombolysis trials, higher rates of symptomatic intracerebral haemorrhage (sICH) were found than in trials with intravenous (IV) recombinant tissue plasminogen activator (tPA); this observation could have been due to the inclusion of more severely affected patients in IA thrombolysis trials. In the present study, we investigated the rate of sICH in IA and combined IV + IA thrombolysis versus IV thrombolysis after adjusting for differences in clinical and MRI parameters. Methods: In this multicenter study, we systematically analyzed data from 645 patients with anterior-circulation strokes treated with either IV or IA thrombolysis within 6 h following symptom onset. Thrombolytic regimens included (1) IV tPA treatment (n = 536) and (2) IA treatment with either tPA or urokinase (n = 74) or (3) combined IV + IA treatment with either tPA or urokinase (n = 35). Results: 44 (6.8%) patients developed sICH. sICH patients had significantly higher scores on the National Institutes of Health Stroke Scale (NIHSS) at admission and pretreatment DWI lesions. The sICH risk was 5.2% (n = 28) in IV thrombolysis, which is significantly lower than in IA (12.5%, n = 9) or IV + IA thrombolysis (20%, n = 7). In a binary logistic regression analysis including age, NIHSS score, time to thrombolysis, initial diffusion weighted imaging lesion size, mode of thrombolytic treatment and thrombolytic agent, the mode of thrombolytic treatment remained an independent predictor for sICH. The odds ratio for IA or IV + IA versus IV treatment was 3.466 (1.19–10.01, 95% CI, p < 0.05). Conclusion: In this series, IA and IV + IA thrombolysis is associated with an increased sICH risk as compared to IV thrombolysis, and this risk is independent of differences in baseline parameters such as age, initial NIHSS score or pretreatment lesion size.