MR diffusion-weighted imaging and outcome prediction after ischemic stroke

Predictive value of follow-up infarct volume on functional outcomes in middle cerebral artery M2 segment vessel occlusion stroke treated with mechanical thrombectomy

BACKGROUND

Medium vessel occlusion (MeVO) strokes, particularly affecting the M2 segment of the middle cerebral artery, represent a critical proportion of acute ischemic strokes, posing significant challenges in management and outcome prediction. The efficacy of mechanical thrombectomy (MT) in MeVO stroke may warrant reliable predictors of functional outcomes. This study aimed to investigate the prognostic value of follow-up infarct volume (FIV) for predicting 90-day functional outcomes in MeVO stroke patients undergoing MT.

METHODS

This multicenter, retrospective cohort study analyzed data from the Multicenter Analysis of primary Distal medium vessel occlusions: effect of Mechanical Thrombectomy (MAD-MT) registry, covering patients with acute ischemic stroke due to M2 segment occlusion treated with MT. We examined the relationship between 90-day functional outcomes, measured by the modified Rankin Scale (mRS), and follow-up infarct volume (FIV), assessed through CT or MRI within 12-36 h post-MT.

RESULTS

Among 130 participants, specific FIV thresholds were identified with high specificity and sensitivity for predicting outcomes. A FIV ⩽5 ml was highly specific for predicting favorable and excellent outcomes. The optimal cut-off for both prognostications was identified at ⩽15 ml by the Youden Index, with significant reductions in the likelihood of favorable outcomes observed above a 40 ml threshold. Receiver Operator Curve (ROC) analyses confirmed FIV as a superior predictor of functional outcomes compared to traditional recanalization scores, such as final modified thrombolysis in cerebral infarction score (mTICI). Multivariable analysis further highlighted the inverse relationship between FIV and positive functional outcomes.

CONCLUSIONS

FIV within 36 h post-MT serves as a potent predictor of 90-day functional outcomes in patients with M2 segment MeVO strokes. Establishing FIV thresholds may aid in the prognostication of stroke outcomes, suggesting a role for FIV in guiding post intervention treatment decisions and informing clinical practice. Future research should focus on validating these findings across diverse patient populations and exploring the integration of FIV measurements with other clinical and imaging markers to enhance outcome prediction accuracy.

Breaking with a dogma: persisting diffusion restrictions (pDWI) in follow-up after endovascular treatment for stroke

BACKGROUND

Post-stroke diffusion weighted imaging (DWI) signal transformation of the infarct core, which results in high apparent diffusion coefficient (ADC) values and variable DWI signal intensity, is completed no later than 1 month after onset of ischemia. We observed frequent exceptions to this timeline of change in DWI signal, which led to uncertainties in further clinical patient management.

METHODS

A prospective single-center study of patients treated with mechanical thrombectomy of a large vessel occlusion in the anterior circulation was conducted. Patients received high-resolution MRI at 3T, including DWI, in the acute post-stroke phase and in the follow-up after 3-12 months.

RESULTS

Overall, 78 patients (45 men) of mean age 63.6 years were evaluated. We identified persisting or new diffusion restriction in 29 of the 78 patients (37.2%) on follow-up imaging. Diffusion restrictions in a different location from the infarct core, representing new (sub-)acute ischemia, were observed in four patients (5.1%). Smaller areas of persisting diffusion restriction (pDWI lesions with high DWI signal and reduced ADC values) within the former infarct core were observed in 25 patients (32.1%) without clinical evidence of recurrent stroke, but with worse outcome scores at follow-up compared with patients without pDWI lesions. The presence of pDWI lesions is associated with a large primary infarct core (multivariate regression OR 1.03 (95% CI 1.01 to 1.05); p<0.01), mediating the relationship between pDWI lesions and clinical outcome.

CONCLUSION

Smaller foci of persisting diffusion restriction (pDWI lesions) in the follow-up after endovascular treatment for stroke are frequent and likely represent a slowed ADC signal progression within a formerly large infarct core.

Prognosticating Acute Ischemic Stroke and Estimating the Feasibility of Mapping Stroke Volume to the Functional Outcomes Using Diffusion-Weighted Images: A Systematic Review Protocol

Introduction

Diffusion-weighted image or DWI is commonly used to provide valuable and diverse information on acute stroke in tertiary care hospitals. DWI is a sensitive and accurate method for identifying the infarct core and can expose the area of cerebral infarction within a few hours of onset. This systematic review is planned to evaluate the measurement of stroke volume on DWI and correlate it with functional outcomes (modified ranking scale).

Method

We have adhered to the PRISMA-P checklist to report this systematic review protocol. PubMed, Web of Science, Scopus, and TRIP (Turning Research into Practice) databases will be searched. Two independent reviewers will screen the records, extract data, and critically appraise the studies. A checklist for critical appraisal will be applied for data abstraction, and data extraction will be done using predictive modeling for systematic reviews. The risk of bias will be measured by the Prediction Model Risk of Bias Assessment Tool (PROBAST). The meta-analysis will be considered only if included studies have adequate data, and STATA statistical package version 13.1 will be used for performing a meta-analysis. A narrative synthesis will be performed if meta-analysis is not possible.

Ethics and Dissemination

As this review will focus on secondary information, there is no ethical consideration required. We will disseminate our findings by publishing our analysis in a peer-reviewed journal.

Protocol Registration

In Prospective Register of Systematic Reviews (CRD42019141840).

MRI whole-lesion texture analysis on ADC maps for the prognostic assessment of ischemic stroke

Background

This study aims is to explore whether it is feasible to use magnetic resonance texture analysis (MRTA) in order to distinguish favorable from unfavorable function outcomes and determine the prognostic factors associated with favorable outcomes of stroke.

Methods

The retrospective study included 103 consecutive patients who confirmed unilateral anterior circulation subacute ischemic stroke by computed tomography angiography between January 2018 and September 2019. Patients were divided into favorable outcome (modified Rankin scale, mRS ≤ 2) and unfavorable outcome (mRS > 2) groups according to mRS scores at day 90. Two radiologists manually segmented the infarction lesions based on diffusion-weighted imaging and transferred the images to corresponding apparent diffusion coefficient (ADC) maps in order to extract texture features. The prediction models including clinical characteristics and texture features were built using multiple logistic regression. A univariate analysis was conducted to assess the performance of the mean ADC value of the infarction lesion. A Delong’s test was used to compare the predictive performance of models through the receiver operating characteristic curve.

Results

The mean ADC performance was moderate [AUC = 0.60, 95% confidence interval (CI) 0.49–0.71]. The texture feature model of the ADC map (tADC), contained seven texture features, and presented good prediction performance (AUC = 0.83, 95%CI 0.75–0.91). The energy obtained after wavelet transform, and the kurtosis and skewness obtained after Laplacian of Gaussian transformation were identified as independent prognostic factors for the favorable stroke outcomes. In addition, the combination of the tADC model and clinical characteristics (hypertension, diabetes mellitus, smoking, and atrial fibrillation) exhibited a subtly better performance (AUC = 0.86, 95%CI 0.79–0.93; P > 0.05, Delong’s).

Conclusion

The models based on MRTA on ADC maps are useful to evaluate the clinical function outcomes in patients with unilateral anterior circulation ischemic stroke. Energy obtained after wavelet transform, kurtosis obtained after Laplacian of Gaussian transform, and skewness obtained after Laplacian of Gaussian transform were identified as independent prognostic factors for favorable stroke outcomes.

Noncoding RNA as Diagnostic and Prognostic Biomarkers in Cerebrovascular Disease

Noncoding RNAs (ncRNAs), such as microRNAs, long noncoding RNAs, and circular RNAs, play an important role in the pathophysiology of cerebrovascular diseases (CVDs). They are effectively detectable in body fluids, potentially suggesting new biomarkers for the early detection and prognosis of CVDs. In this review, the physiological functions of circulating ncRNAs and their potential role as diagnostic and prognostic markers in patients with cerebrovascular diseases are discussed, especially in acute ischemic stroke, subarachnoid hemorrhage, and moyamoya disease.

Association of cerebral microvascular perfusion and diffusion dynamics detected by intravoxel incoherent motion-diffusion weighted imaging with initial neurological function and clinical outcome in acute ischemic stroke

Background

This work aimed to explore the association of cerebral microvascular perfusion and diffusion dynamics measured by intravoxel incoherent motion (IVIM) imaging with initial neurological function and clinical outcome in acute stroke.

Methods

In total, 39 patients were assessed with admission National Institutes of Health Stroke Scale (NIHSS) and day-90 modified Rankin Scale (mRS). The parametrical maps of IVIM were obtained, including apparent diffusion coefficient (ADC), pseudo-diffusion coefficient (D*), true diffusion coefficient (D) and perfusion fraction (f). The fD* was the product of f and D*. Moreover, the ratios of lesioned/contralateral parameters (rADC, rD, rD*, rf and rfD*) were also obtained. The differences of these parameters between the poor outcome group and good outcome group were evaluated. Partial correlation analysis was used to evaluate the correlations between the admission NIHSS/day-90 mRS and each parameter ratio, with lesion volumes controlled.

Results

The ADC, D, D*, f and fD* values of lesions were significantly reduced than those of the contralateral regions. The rADC and rD were significantly decreased in the poor outcome group than good outcome group (all p < 0.01). With lesion volume controlled, rADC showed a weak negative correlation (r = −0.340, p = 0.037) and a notable negative correlation (r = −0.688, p < 0.001) with admission NIHSS score and day-90 mRS score, respectively. In addition, rD showed a strong negative correlation (r = −0.731, p < 0.001) with day-90 mRS score.

Conclusion

Significant negative correlations were revealed between IVIM derived diffusion dynamics parameters and initial neurological function as well as clinical outcome for patients with acute ischemic stroke. IVIM can be therefore suggested as an effective non-invasive method for evaluating the acute ischemic stroke.

The association between telomere length and ischemic stroke risk and phenotype

The chronological age of a person is a key determinant of etiology and prognosis in the setting of ischemic stroke. Telomere length, an indicator of biological aging, progressively shortens with every cell cycle. Herein, we determined telomere length from peripheral blood leukocytes by Southern blot analyses in a prospective cohort of ischemic stroke patients (n = 163) and equal number of non-stroke controls and evaluated its association with various ischemic stroke features including etiology, severity, and outcome. A shorter telomere length (i.e. lowest quartile; ≤ 5.5 kb) was significantly associated with ischemic stroke (OR 2.95, 95% CI 1.70–5.13). This significant relationship persisted for all stroke etiologies, except for other rare causes of stroke. No significant association was present between admission lesion volume and telomere length; however, patients with shorter telomeres had higher admission National Institutes of Health Stroke Scale scores when adjusted for chronological age, risk factors, etiology, and infarct volume (p = 0.046). On the other hand, chronological age, but not telomere length, was associated with unfavorable outcome (modified Rankin scale > 2) and mortality at 90 days follow-up. The association between shorter telomere length and more severe clinical phenotype at the time of admission, might reflect reduced resilience of cerebral tissue to ischemia as part of biological aging.

Diffusion weighted imaging in acute ischemic stroke: A review of its interpretation pitfalls and advanced diffusion imaging application

Diffusion weighted imaging (DWI) is a widely used imaging technique to evaluate patients with stroke. It can detect brain ischemia within minutes of stroke onset. However, DWI has few potential pitfalls that should be recognized during interpretation. DWI lesion could be reversible in the early hours of stroke and the entire lesion may not represent ischemic core. False negative DWI could lead to diagnosis of DWI negative stroke or to a missed stroke diagnosis. Ischemic stroke mimics can occur on DWI with non-cerebrovascular neurological conditions. In this article, the history of DWI, its clinical applications, and potential pitfalls for use in acute ischemic stroke are reviewed. Advanced diffusion imaging techniques with reference to Diffusion Kurtosis Imaging and Diffusion Tensor Imaging that has been studied to evaluate ischemic core are discussed.

Scoring of Middle Cerebral Artery Collaterals Predicts RAPID CT-Perfusion Analysis and Short-Term Outcomes in Acute Ischemic Stroke Patients Undergoing Thrombectomy

OBJECTIVE

The rapid processing of perfusion and diffusion (RAPID) system for automating perfusion and diffusion data from head computed tomography has improved acute ischemic stroke treatment by quickly and accurately identifying those patients who may benefit from thrombectomy. Collateral scoring (CS) of cerebral arteries using computed tomography angiography (CTA) has proven useful in predicting postintervention infarct volumes and functional outcomes in ischemic stroke patients. Here we evaluate the relationship between CS and RAPID software in an effort to augment triage and provide improved predictability of functional outcomes in ischemic stroke patients.

METHODS

A retrospective review of 77 mechanical thrombectomy patients from January 2017 to October 2018 with large vessel occlusions of the anterior circulation who underwent RAPID and CTA imaging was performed. Baseline characteristics, RAPID data, CS, modified Rankin Scale score, and procedural data were collected. magnetic resonance imaging was used to calculate the postintervention stroke volume.

RESULTS

CS inversely correlates with the volume of RAPID cerebral blood flow <30% (β= -18.131, 95% confidence interval [CI] -24.384 to -11.879, P < 0.001), RAPID Tmax >6s (β= -22.205, 95% CI -39.125 to -5.285, P = 0.011), postintervention stroke volume (β= -30.637, 95% CI -41.554 to -19.720, P < 0.001), and discharge National Institutes of Health Stroke Scale score (β= -1.922, 95% CI -3.575 to -0.269, P = 0.023).

CONCLUSIONS

CS on CTA may be a useful way to identify patients who would benefit from mechanical thrombectomy and predict functional outcomes postintervention. CS may allow the stroke team to optimize the care of patients who may not be able to obtain RAPID analysis.

Predictors of Lesion Cavitation After Recent Small Subcortical Stroke

Morphologic evolution of recent small subcortical infarcts (RSSI) ranges from lesion disappearance to lacune formation and the reasons for this variability are still poorly understood. We hypothesized that diffusion tensor imaging (DTI) and blood-brain-barrier (BBB) abnormalities early on can predict tissue damage 1 year after an RSSI. We studied prospectively recruited patients with a symptomatic MRI-defined RSSI who underwent baseline and two pre-specified MRI examinations at 1-3-month and 1-year post-stroke. We defined the extent of long-term tissue destruction, termed cavitation index, as the ratio of the 1-year T1-weighted cavity volume to the baseline RSSI volume on FLAIR. We calculated fractional anisotropy and mean diffusivity (MD) of the RSSI and normal-appearing white matter, and BBB leakage in different tissues on dynamic contrast-enhanced MRI. Amongst 60 patients, at 1-year post-stroke, 44 patients showed some degree of RSSI cavitation on FLAIR, increasing to 50 on T2- and 56 on T1-weighted high-resolution scans, with a median cavitation index of 7% (range, 1-36%). Demographic, clinical, and cerebral small vessel disease features were not associated with the cavitation index. While lower baseline MD of the RSSI (r_s = - 0.371; p = 0.004) and more contrast leakage into CSF (r_s = 0.347; p = 0.007) were associated with the cavitation index in univariable analysis, only BBB leakage in CSF remained independently associated with cavitation (beta = 0.315, p = 0.046). Increased BBB leakage into CSF may indicate worse endothelial dysfunction and increased risk of tissue destruction post RSSI. Although cavitation was common, it only affected a small proportion of the original RSSI.

Associations Between Diffusion Dynamics and Functional Outcome in Acute and Early Subacute Ischemic Stroke

PURPOSE

The current study aimed to investigate the associations between diffusion dynamics of ischemic lesions and clinical functional outcome of acute and early subacute stroke.

MATERIAL AND METHODS

A total of 80 patients with first ever infarcts in the territory of the middle cerebral artery underwent multi-b-values diffusion-weighted imaging and diffusion kurtosis imaging. Multiple diffusion parameters were generated in postprocessing using different diffusion models. Long-term functional outcome was evaluated with modified Rankin scale (mRS) at 6 months post-stroke. Good functional outcome was defined as mRS score ≤ 2 and poor functional outcome was defined as mRS score ≥ 3. Univariate analysis was used to compare the diffusion parameters and clinical features between patients with poor and good functional outcome. Significant parameters were further analyzed for correlations with functional outcome using partial correlation.

RESULTS

In univariate analyses, standard-b-values apparent diffusion coefficient (ADC_st) ratio and fractional anisotropy (FA) ratio of acute stroke, ADC_st ratio and mean kurtosis (MK) ratio of early subacute stroke were statistically different between patients with poor outcome and good outcome (P < 0.05). When the potential confounding factor of lesion volume was controlled, only FA ratio of acute stroke, ADC_st ratio and MK ratio of early subacute stroke remained correlated with the functional outcome (P < 0.05).

CONCLUSION

Diffusion dynamics are correlated with the clinical functional outcome of ischemic stroke. This correlation is independent of the effect of lesion volume and is specific to the time period between symptom onset and imaging. More effort is needed to further investigate the predictive value of diffusion-weighted imaging.

Relating Acute Lesion Loads to Chronic Outcome in Ischemic Stroke-An Exploratory Comparison of Mismatch Patterns and Predictive Modeling

Objectives: To investigate the relationship between imaging features derived from lesion loads and 3 month clinical assessments in ischemic stroke patients. To support clinically implementable predictive modeling with information from lesion-load features. Methods: A retrospective cohort of ischemic stroke patients was studied. The dataset was dichotomized based on revascularization treatment outcome (TICI score). Three lesion delineations were derived from magnetic resonance imaging in each group: two clinically implementable (threshold based and fully automatic prediction) and 90-day follow-up as final groundtruth. Lesion load imaging features were created through overlay of the lesion delineations on a histological brain atlas, and were correlated with the clinical assessment (NIHSS). Significance of the correlations was assessed by constructing confidence intervals using bootstrap sampling. Results: Overall, high correlations between lesion loads and clinical score were observed (up to 0.859). Delineations derived from acute imaging yielded on average somewhat lower correlations than delineations derived from 90-day follow-up imaging. Correlations suggest that both total lesion volume and corticospinal tract lesion load are associated with functional outcome, and in addition highlight other potential areas associated with poor clinical outcome, including the primary somatosensory cortex BA3a. Fully automatic prediction was comparable to ADC threshold-based delineation on the successfully treated cohort and superior to the Tmax threshold-based delineation in the unsuccessfully treated cohort. Conclusions: The confirmation of established predictors for stroke outcome (e.g., corticospinal tract integrity and total lesion volume) gives support to the proposed methodology-relating acute lesion loads to 3 month outcome assessments by way of correlation. Furthermore, the preliminary results indicate an association of further brain regions and structures with three month NIHSS outcome assessments. Hence, prediction models might observe an increased accuracy when incorporating regional (instead of global) lesion loads. Also, the results lend support to the clinical utilization of the automatically predicted volumes from FASTER, rather than the simpler DWI and PWI lesion delineations.

Structural Plasticity in Adulthood with Motor Learning and Stroke Rehabilitation

The development of advanced noninvasive techniques to image the human brain has enabled the demonstration of structural plasticity during adulthood in response to motor learning. Understanding the basic mechanisms of structural plasticity in the context of motor learning is essential to improve motor rehabilitation in stroke patients. Here, we review and discuss the emerging evidence for motor-learning-related structural plasticity and the implications for stroke rehabilitation. In the clinical context, a few studies have started to assess the effects of rehabilitation on structural measures to understand recovery poststroke and additionally to predict intervention outcomes. Structural imaging will likely have a role in the future in providing measures that inform patient stratification for optimal outcomes.

Predicting the pattern and severity of chronic post-stroke language deficits from functionally-partitioned structural lesions

There is an ever-increasing wealth of knowledge arising from basic cognitive and clinical neuroscience on how speech and language capabilities are organised in the brain. It is, therefore, timely to use this accumulated knowledge and expertise to address critical research challenges, including the ability to predict the pattern and level of language deficits found in aphasic patients (a third of all stroke cases). Previous studies have mainly focused on discriminating between broad aphasia dichotomies from purely anatomically-defined lesion information. In the current study, we developed and assessed a novel approach in which core language areas were mapped using principal component analysis in combination with correlational lesion mapping and the resultant ‘functionally-partitioned’ lesion maps were used to predict a battery of 21 individual test scores as well as aphasia subtype for 70 patients with chronic post-stroke aphasia. Specifically, we used lesion information to predict behavioural scores in regression models (cross-validated using 5-folds). The winning model was identified through the adjusted R² (model fit to data) and performance in predicting holdout folds (generalisation to new cases). We also used logistic regression to predict fluent/non-fluent status and aphasia subtype. Functionally-partitioned models generally outperformed other models at predicting individual tests, fluency status and aphasia subtype.

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Predict the pattern and level of language deficits found in chronic aphasic patients

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Use principal component analysis to identify functional lesion maps

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Functionally-partitioned lesion maps used as predictor variables instead of lesion volume

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Functionally-partitioned lesion model plus age produced the best regression model

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Model can successfully predict fluent/non-fluent types and aphasia classification

Contribution of Neuro-Imaging for Prediction of Functional Recovery after Ischemic Stroke

Prediction measures of recovery and outcome after stroke perform with only modest levels of accuracy if based only on clinical data. Prediction scores can be improved by including morphologic imaging data, where size, location, and development of the ischemic lesion is best documented by magnetic resonance imaging. In addition to the primary lesion, the involvement of fiber tracts contributes to prognosis, and consequently the use of diffusion tensor imaging (DTI) to assess primary and secondary pathways improves the prediction of outcome and of therapeutic effects. The recovery of ischemic tissue and the progression of damage are dependent on the quality of blood supply. Therefore, the status of the supplying arteries and of the collateral flow is not only crucial for determining eligibility for acute interventions, but also has an impact on the potential to integrate areas surrounding the lesion that are not typically part of a functional network into the recovery process. The changes in these functional networks after a localized lesion are assessed by functional imaging methods, which additionally show altered pathways and activated secondary centers related to residual functions and demonstrate changes in activation patterns within these networks with improved performance. These strategies in some instances record activation in secondary centers of a network, for example, also in homolog contralateral areas, which might be inhibitory to the recovery of primary centers. Such findings might have therapeutic consequences, for example, image-guided inhibitory stimulation of these areas. In the future, a combination of morphological imaging including DTI of fiber tracts and activation studies during specific tasks might yield the best information on residual function, reserve capacity, and prospects for recovery after ischemic stroke.

Right insular infarction and mortality after ischaemic stroke

BACKGROUND AND PURPOSE

Several studies have described an association between insular infarction and mortality. Large infarcts often include the insula and lesion size is associated with mortality. We hypothesized that there is an association between insular infarction and mortality independent of lesion volume.

METHODS

We included consecutive stroke patients between 1 September 2008 and 11 November 2012 from the 1000Plus database with an acute ischaemic lesion on diffusion-weighted imaging on day 1 and a completed 90-day follow-up. Insular infarct location was determined using the in-house software Stroke Lesion Atlas. In multiple Cox regression analysis (dependent variable: mortality), we adjusted for insular infarcts, age, lesion volume, history of atrial fibrillation, National Institutes of Health Stroke Scale and previous stroke.

RESULTS

We included 736 patients, of whom 168 had an insular infarction. Within a medium follow-up time of 107 days, cumulative survival was 90% in patients with insular infarction and 99% in patients without insular infarction (P < 0.001). Right insular infarction was independently associated with mortality (hazard ratio, 2.60; confidence interval, 1.3-5.4; P = 0.010).

CONCLUSIONS

In our study, right insular involvement was a prognostic marker for mortality after ischaemic stroke. A selection bias towards patients able to give informed consent warrants further studies.

Can Neurological Biomarkers of Brain Impairment Be Used to Predict Poststroke Motor Recovery? A Systematic Review

Background There is growing interest to establish recovery biomarkers, especially neurological biomarkers, in order to develop new therapies and prediction models for the promotion of stroke rehabilitation and recovery. However, there is no consensus among the neurorehabilitation community about which biomarker(s) have the highest predictive value for motor recovery. Objective To review the evidence and determine which neurological biomarker(s) meet the high evidence quality criteria for use in predicting motor recovery. Methods We searched databases for prognostic neuroimaging/neurophysiological studies. Methodological quality of each study was assessed using a previously employed comprehensive 15-item rating system. Furthermore, we used the GRADE approach and ranked the overall evidence quality for each category of neurologic biomarker. Results Seventy-one articles met our inclusion criteria; 5 categories of neurologic biomarkers were identified: diffusion tensor imaging (DTI), transcranial magnetic stimulation (TMS), functional magnetic resonance imaging (fMRI), conventional structural MRI (sMRI), and a combination of these biomarkers. Most studies were conducted with individuals after ischemic stroke in the acute and/or subacute stage (~70%). Less than one-third of the studies (21/71) were assessed with satisfactory methodological quality (80% or more of total quality score). Conventional structural MRI and the combination biomarker categories ranked "high" in overall evidence quality. Conclusions There were 3 prevalent methodological limitations: (a) lack of cross-validation, (b) lack of minimal clinically important difference (MCID) for motor outcomes, and (c) small sample size. More high-quality studies are needed to establish which neurological biomarkers are the best predictors of motor recovery after stroke. Finally, the quarter-century old methodological quality tool used here should be updated by inclusion of more contemporary methods and statistical approaches.

Predictors of clinical outcome in patients with acute perforating artery infarction

BACKGROUND AND PURPOSE

We aimed to determine the predictive factors for super-acute perforating artery infarctions (PAI) involving lenticulostriate arteries infarctions (LSAI), anterior pontine arteries infarctions (APAI) and thalamic arteries infarctions (TAI). Whether intravenous thrombolysis (iv-tPA) therapy would influence the clinical outcome was also studied.

METHODS

We analyzed 84 consecutive patients within 12h of stroke symptom onset from January 2008 to June 2015. All patients had an imaging-proven acute infarction in the perforating territory of LSA (n=53), TA (n=21) and APA (n=10). Favorable clinical outcome was defined as modified Rankin Scale ≤1 at 90days. Patients were divided into groups according to clinical outcome, lesion location and thrombolysis therapy. Baseline demographic data, past medical history, National Institutes of Health Stroke Scale (NIHSS) score and infarction volume were compared between groups.

RESULTS

Eighty-four patients were recruited (median age: 61y; 67.9% male). All patients with TAI (n=21), 34/53 (64.2%) patients with LSAI and 4/10 (40%) patients with APAI achieved favorable clinical outcome (mRS≤1). Ninety-day clinical outcome was associated with age, previous stroke, baseline NIHSS, infarct location, infarct volume. Intravenous thrombolysis improved 24h NIHSS, but was not significantly associated with favorable outcome at 90days. In multivariate analysis, only previous stroke/TIA (OR 0.09, 95%CI 0.01-0.68, p=0.020) and infarct volume (OR 0.64, 95%CI 0.43-0.96, p=0.032) were independently associated with the outcome of acute PAI at 90days.

CONCLUSIONS

Previous stroke/TIA, infarct location and infarct volume were independently associated with the short-term clinical outcome of acute PAI.

A new prognostic scale for the early prediction of ischemic stroke recovery mainly based on traditional Chinese medicine symptoms and NIHSS score: a retrospective cohort study

Background

Ischemic stroke (IS) is a common disease, often resulting in death or disability. Previous studies on prognosis of stroke mainly focused on the baseline condition or modern expensive tests. However, the change of clinical symptoms during acute stage is considerably neglected. In our study, we aim to develop a new prognostic scale to predict the 90-day outcome of IS patients.

Methods

In this retrospective cohort study, a secondary data analysis was performed on 489 patients extracted from 1046 patients of 4 hospitals. A new prognostic scale was constructed to predict the recovery of IS mainly based on the National Institutes of Health Stroke Scale (NIHSS) score, traditional Chinese Medicine (TCM) symptoms & signs and the changes during the first 3 days of patients in the 3 TCM hospitals. Receiver Operating Characteristic (ROC) curve was used to determine the cutoff point for prediction. In the end, the scale was used to test the outcome of IS patients in Xuanwu hospital.

Results

The new prognostic scale was composed of 8 items including age degree (OR = 3.32; 95 % CI: 1.72–6.42), history of diabetes mellitus (DM) (OR = 2.20; 95 % CI: 1.19–4.08), NIHSS score (OR = 3.08; 95 % CI: 2.16–4.40), anxiety (OR = 3.17; 95 % CI: 1.90–5.29) and irritability (OR = 4.61; 95 % CI: 1.36–15.63) on the 1st day of illness onset, change in NIHSS score (OR = 2.49; 95 % CI: 1.31–4.73), and circumrotating (OR = 7.80; 95 % CI: 1.98–30.64) and tinnitus (OR = 13.25; 95 % CI: 1.55–113.34) during the first 3 days of stroke onset. The total score of the scale was 16.5 and the cutoff point was 9.5, which means patients would have poor outcome at 90 days of stroke onset if the score was higher than 9.5. The new scale was validated on the data of Xuanwu hospital, and the value of its sensitivity, specificity and overall accuracy were 69.6 %, 83.3 % and 75.0 % respectively.

Conclusions

The 8-item scale, mainly based on TCM symptoms, NIHSS score and their changes during the first 3 days, can predict the 90-day outcome for IS patients while it still needs to be further validated and optimized clinically.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-015-0903-1) contains supplementary material, which is available to authorized users.

Clinically Confirmed Stroke With Negative Diffusion-Weighted Imaging Magnetic Resonance Imaging: Longitudinal Study of Clinical Outcomes, Stroke Recurrence, and Systematic Review

BACKGROUND AND PURPOSE

We sought to establish whether the presence (versus absence) of a lesion on magnetic resonance imaging (MRI) with diffusion weighting (DWI-MRI) at presentation with acute stroke is associated with worse clinical outcomes at 1 year.

METHODS

We recruited consecutive patients with a nondisabling ischemic stroke and performed DWI-MRI. Patients were followed up at 1 year to establish stroke recurrence (clinical or on MRI), cognitive impairment (Addenbrooke Cognitive Assessment Revised,<88) and modified Rankin Scale.

RESULTS

A median of 4 days post stroke, one third (76/264; 29%) of patients did not have a DWI lesion (95% confidence interval, 23%-35%). There was no statistically significant difference between those with and without a DWI lesion with respect to age or vascular risk factors. Patients without a lesion were more likely to be women or have previous stroke. At 1 year, 11 of 76 (14%) patients with a DWI-negative index stroke had a clinical diagnosis of recurrent stroke or transient ischemic attack, 33% had cognitive impairment (Addenbrooke Cognitive Assessment Revised<88), and 40% still had modified Rankin Scale>1, no different from DWI-positive patients; DWI-positive patients were more likely to have a new lesion on MRI (14%), symptomatic or asymptomatic, than DWI-negative patients (2%; P=0.02). Our data were consistent with 6 other studies (total n=976), pooled proportion of DWI-negative patients was 21% (95% confidence interval, 12%-32%).

CONCLUSIONS

Nearly one third of patients with nondisabling stroke do not have a relevant lesion on acute DWI-MRI. Patients with negative DWI-MRI had no better prognosis than patients with a lesion. DWI-negative stroke patients should receive secondary prevention.

Younger Stroke Patients With Large Pretreatment Diffusion-Weighted Imaging Lesions May Benefit From Endovascular Treatment

BACKGROUND AND PURPOSE

Lesion volume on diffusion-weighted magnetic resonance imaging (DWI) before acute stroke therapy is a predictor of outcome. Therefore, patients with large volumes are often excluded from therapy. The aim of this study was to analyze the impact of endovascular treatment in patients with large DWI lesion volumes (>70 mL).

METHODS

Three hundred seventy-two patients with middle cerebral or internal carotid artery occlusions examined with magnetic resonance imaging before treatment since 2004 were included. Baseline data and 3 months outcome were recorded prospectively. DWI lesion volumes were measured semiautomatically.

RESULTS

One hundred five patients had lesions >70 mL. Overall, the volume of DWI lesions was an independent predictor of unfavorable outcome, survival, and symptomatic intracerebral hemorrhage (P<0.001 each). In patients with DWI lesions >70 mL, 11 of 31 (35.5%) reached favorable outcome (modified Rankin scale score, 0-2) after thrombolysis in cerebral infarction 2b-3 reperfusion in contrast to 3 of 35 (8.6%) after thrombolysis in cerebral infarction 0-2a reperfusion (P=0.014). Reperfusion success, patient age, and DWI lesion volume were independent predictors of outcome in patients with DWI lesions >70 mL. Thirteen of 66 (19.7%) patients with lesions >70 mL had symptomatic intracerebral hemorrhage with a trend for reduced risk with avoidance of thrombolytic agents.

CONCLUSIONS

There was a growing risk for poor outcome and symptomatic intracerebral hemorrhage with increasing pretreatment DWI lesion volumes. Nevertheless, favorable outcome was achieved in every third patient with DWI lesions >70 mL after successful endovascular reperfusion, whereas after poor or failed reperfusion, outcome was favorable in only every 12th patient. Therefore, endovascular treatment might be considered in patients with large DWI lesions, especially in younger patients.

The impact of stroke unit care on outcome in a Scottish stroke population, taking into account case mix and selection bias

BACKGROUND AND AIM

Randomised trials indicate that stroke unit care reduces morbidity and mortality after stroke. Similar results have been seen in observational studies but many have not corrected for selection bias or independent predictors of outcome. We evaluated the effect of stroke unit compared with general ward care on outcomes after stroke in Scotland, adjusting for case mix by incorporating the six simple variables (SSV) model, also taking into account selection bias and stroke subtype.

METHODS

We used routine data from National Scottish datasets for acute stroke patients admitted between 2005 and 2011. Patients who died within 3 days of admission were excluded from analysis. The main outcome measures were survival and discharge home. Multivariable logistic regression was used to estimate the OR for survival, and adjustment was made for the effect of the SSV model and for early mortality. Cox proportional hazards model was used to estimate the hazard of death within 365 days.

RESULTS

There were 41 692 index stroke events; 79% were admitted to a stroke unit at some point during their hospital stay and 21% were cared for in a general ward. Using the SSV model, we obtained a receiver operated curve of 0.82 (SE 0.002) for mortality at 6 months. The adjusted OR for survival at 7 days was 3.11 (95% CI 2.71 to 3.56) and at 1 year 1.43 (95% CI 1.34 to 1.54) while the adjusted OR for being discharged home was 1.19 (95% CI 1.11 to 1.28) for stroke unit care.

CONCLUSIONS

In routine practice, stroke unit admission is associated with a greater likelihood of discharge home and with lower mortality up to 1 year, after correcting for known independent predictors of outcome, and excluding early non-modifiable mortality.

An assessment of the cost-effectiveness of magnetic resonance, including diffusion-weighted imaging, in patients with transient ischaemic attack and minor stroke: a systematic review, meta-analysis and economic evaluation

BACKGROUND

Patients with transient ischaemic attack (TIA) or minor stroke need rapid treatment of risk factors to prevent recurrent stroke. ABCD2 score or magnetic resonance diffusion-weighted brain imaging (MR DWI) may help assessment and treatment.

OBJECTIVES

Is MR with DWI cost-effective in stroke prevention compared with computed tomography (CT) brain scanning in all patients, in specific subgroups or as 'one-stop' brain-carotid imaging? What is the current UK availability of services for stroke prevention?

DATA SOURCES

Published literature; stroke registries, audit and randomised clinical trials; national databases; survey of UK clinical and imaging services for stroke; expert opinion.

REVIEW METHODS

Systematic reviews and meta-analyses of published/unpublished data. Decision-analytic model of stroke prevention including on a 20-year time horizon including nine representative imaging scenarios.

RESULTS

The pooled recurrent stroke rate after TIA (53 studies, 30,558 patients) is 5.2% [95% confidence interval (CI) 3.9% to 5.9%] by 7 days, and 6.7% (5.2% to 8.7%) at 90 days. ABCD2 score does not identify patients with key stroke causes or identify mimics: 66% of specialist-diagnosed true TIAs and 35-41% of mimics had an ABCD2 score of ≥ 4; 20% of true TIAs with ABCD2 score of < 4 had key risk factors. MR DWI (45 studies, 9078 patients) showed an acute ischaemic lesion in 34.3% (95% CI 30.5% to 38.4%) of TIA, 69% of minor stroke patients, i.e. two-thirds of TIA patients are DWI negative. TIA mimics (16 studies, 14,542 patients) make up 40-45% of patients attending clinics. UK survey (45% response) showed most secondary prevention started prior to clinic, 85% of primary brain imaging was same-day CT; 51-54% of patients had MR, mostly additional to CT, on average 1 week later; 55% omitted blood-sensitive MR sequences. Compared with 'CT scan all patients' MR was more expensive and no more cost-effective, except for patients presenting at > 1 week after symptoms to diagnose haemorrhage; strategies that triaged patients with low ABCD2 scores for slow investigation or treated DWI-negative patients as non-TIA/minor stroke prevented fewer strokes and increased costs. 'One-stop' CT/MR angiographic-plus-brain imaging was not cost-effective.

LIMITATIONS

Data on sensitivity/specificity of MR in TIA/minor stroke, stroke costs, prognosis of TIA mimics and accuracy of ABCD2 score by non-specialists are sparse or absent; all analysis had substantial heterogeneity.

CONCLUSIONS

Magnetic resonance with DWI is not cost-effective for secondary stroke prevention. MR was most helpful in patients presenting at > 1 week after symptoms if blood-sensitive sequences were used. ABCD2 score is unlikely to facilitate patient triage by non-stroke specialists. Rapid specialist assessment, CT brain scanning and identification of serious underlying stroke causes is the most cost-effective stroke prevention strategy.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Applicable apparent diffusion coefficient of an orthotopic mouse model of gastric cancer by improved clinical MRI diffusion weighted imaging

In vivo imaging studies in animal models are hindered by variables that contribute to poor image quality and measurement reliability. As such we sought to improve the diffusion coefficient (ADC) of an orthotopic mouse model of gastric cancer in diffusion-weighted images (DWI) using alginate moulding and Ultrasonic coupling medium. BGC-823 human gastric cancer cells were subcutaneously injected into the abdomen of nude mice and 1 mm(3) primary tumour was orthotopically transplanted. Alginate and coupling medium were applied to the mice and MRI (T2 and DWI) was performed for 6 weeks. Regions of interest (ROI) were drawn and liver and tumour ADC were evaluated. Using alginate moulding, the mean quality total score of DW imaging was 8.53; however, in control animals this value was 5.20 (p < 0.001). The coefficient of variation of ADC of liver in experimental and control groups were 0.071 and 0.270 (p < 0.001), respectively, suggesting this method may be helpful for DWI studies of important human diseases such as gastric cancer.

Imaging predictors of poststroke depression: methodological factors in voxel-based analysis

OBJECTIVE

The purpose of this study was to explore the relationship between lesion location and poststroke depression using statistical parametric mapping.

METHODS

First episode patients with stroke were assessed within 12 days and at 1-month poststroke. Patients with an a priori defined cut-off score of 11 on the Hospital Anxiety and Depression Scale (HADS) at follow-up were further assessed using the Mini-International Neuropsychiatric Interview (MINI) to confirm a clinical diagnosis of major or minor depression in accordance with Diagnostic and Statistical Manual-IV (DSM-IV) inclusion criteria. Participants were included if they were aged 18-85 years, proficient in English and eligible for MRI. Patients were excluded if they had a confounding diagnosis such as major depressive disorder at the time of admission, a neurodegenerative disease, epilepsy or an imminently life-threatening comorbid illness, subarachnoid or subdural stroke, a second episode of stroke before follow-up and/or a serious impairment of consciousness or language. Infarcts observed on MRI scans were manually segmented into binary images, linearly registered into a common stereotaxic coordinate space. Using statistical parametric mapping, we compared infarct patterns in patients with stroke with and without depression.

RESULTS

27% (15/55 patients) met criteria for depression at follow-up. Mean infarct volume was 19±53 mL and National Institute of Health Stroke Scale (NIHSS) at Time 1 (within 12 days of stroke) was 4±4, indicating a sample of mild strokes. No voxels or clusters were significant after a multiple comparison correction was applied (p>0.05). Examination of infarct maps showed that there was minimal overlap of infarct location between patients, thus invalidating the voxel comparison analysis.

CONCLUSIONS

This study provided inconclusive evidence for the association between infarcts in a specific region and poststroke depression.

Predicting future brain tissue loss from white matter connectivity disruption in ischemic stroke

BACKGROUND AND PURPOSE

The Network Modification (NeMo) Tool uses a library of brain connectivity maps from normal subjects to quantify the amount of structural connectivity loss caused by focal brain lesions. We hypothesized that the Network Modification Tool could predict remote brain tissue loss caused by poststroke loss of connectivity.

METHODS

Baseline and follow-up MRIs (10.7±7.5 months apart) from 26 patients with acute ischemic stroke (age, 74.6±14.1 years, initial National Institutes of Health Stroke Scale, 3.1±3.1) were collected. Lesion masks derived from diffusion-weighted images were superimposed on the Network Modification Tool's connectivity maps, and regional structural connectivity losses were estimated via the Change in Connectivity (ChaCo) score (ie, the percentage of tracks connecting to a given region that pass through the lesion mask). ChaCo scores were correlated with subsequent atrophy.

RESULTS

Stroke lesions' size and location varied, but they were more frequent in the left hemisphere. ChaCo scores, generally higher in regions near stroke lesions, reflected this lateralization and heterogeneity. ChaCo scores were highest in the postcentral and precentral gyri, insula, middle cingulate, thalami, putamen, caudate nuclei, and pallidum. Moderate, significant partial correlations were found between baseline ChaCo scores and measures of subsequent tissue loss (r=0.43, P=4.6×10(-9); r=0.61, P=1.4×10(-18)), correcting for the time between scans.

CONCLUSIONS

ChaCo scores varied, but the most affected regions included those with sensorimotor, perception, learning, and memory functions. Correlations between baseline ChaCo and subsequent tissue loss suggest that the Network Modification Tool could be used to identify regions most susceptible to remote degeneration from acute infarcts.

Activated protein C analog protects from ischemic stroke and extends the therapeutic window of tissue-type plasminogen activator in aged female mice and hypertensive rats

BACKGROUND AND PURPOSE

3K3A-activated protein C (APC) protects young, healthy male rodents after ischemic stroke. 3K3A-APC is currently under development as a neuroprotectant for acute ischemic stroke in humans. Stroke Therapy Academic Industry Roundtable recommends that after initial studies in young, healthy male animals, further studies should be performed in females, aged animals, and animals with comorbid conditions. Here, we studied the effects of delayed 3KA-APC therapy alone and with tissue-type plasminogen activator (tPA) in aged female mice and spontaneously hypertensive rats.

METHODS

We used Stroke Therapy Academic Industry Roundtable recommendations for ensuring good scientific inquiry. Murine recombinant 3K3A-APC (0.2 mg/kg) alone or with recombinant tPA (10 mg/kg) was given intravenously 4 hours after transient middle cerebral artery occlusion in aged female mice and rats and after embolic stroke in spontaneously hypertensive rat. 3K3A-APC was additionally administered within 3 to 7 days after stroke. The neuropathological analysis and neurological scores, foot-fault, forelimb asymmetry, and adhesive removal tests were performed within 7 and 28 days of stroke.

RESULTS

In all models, tPA alone had no effects on the infarct volume or behavior. 3K3A-APC alone or with tPA reduced the infarct volume 7 days after the middle cerebral artery occlusion in aged female mice and embolic stroke in spontaneously hypertensive rat by 62% to 66% and 50% to 53%, respectively, significantly improved (P<0.05) behavior, and eliminated tPA-induced intracerebral microhemorrhages. In aged female mice, 3K3A-APC was protective within 4 weeks of stroke.

CONCLUSIONS

3K3A-APC protects from ischemic stroke and extends the therapeutic window of tPA in aged female mice and in spontaneously hypertensive rat with a comorbid condition.

How Useful is Imaging in Predicting Outcomes in Stroke Rehabilitation?

Neuroimaging plays an important role In acute stroke diagnosis and management, but It Is not routinely used In rehabilitation settings. Incorporating Imaging Information In rehabilitation planning may eventually translate to better outcomes after stroke. Here we review the prediction of outcomes after stroke using magnetic resonance imaging. There are clear and specific relationships between the anatomy of the stroke lesion and impairments at the time of scanning, and at later time points in recovery. However, most studies demonstrate these relationships in groups of patients at the chronic stage. In order to be useful for rehabilitation, neuroimaging needs to provide prognostic information for individual patients at a much earlier stage. Recent studies have used diffusion tensor imaging and functional neuroimaging to address this, with promising results. Combining neuroimaging with clinical and neurophysiological assessments may also be useful. Future work in this area may support the tailoring of rehabilitation for individual patients based on their capacity for neural reorganization and recovery.

Automated core-penumbra quantification in neonatal ischemic brain injury

Neonatal hypoxic-ischemic brain injury (HII) and arterial ischemic stroke (AIS) result in irreversibly injured (core) and salvageable (penumbral) tissue regions. Identification and reliable quantification of salvageable tissue is pivotal to any effective and safe intervention. Magnetic resonance imaging (MRI) is the current standard to distinguish core from penumbra using diffusion-perfusion mismatch (DPM). However, subtle MR signal variations between core-penumbral regions make their visual delineation difficult. We hypothesized that computational analysis of MRI data provides a more accurate assessment of core and penumbral tissue evolution in HII/AIS. We used two neonatal rat-pup models of HII/AIS (unilateral and global hypoxic-ischemia) and clinical data sets from neonates with AIS to test our noninvasive, automated computational approach, Hierarchical Region Splitting (HRS), to detect and quantify ischemic core-penumbra using only a single MRI modality (T2- or diffusion-weighted imaging, T2WI/DWI). We also validated our approach by comparing core-penumbral images (from HRS) to DPM with immunohistochemical validation of HII tissues. Our translational and clinical data results showed that HRS could accurately and reliably distinguish the ischemic core from penumbra and their spatiotemporal evolution, which may aid in the vetting and execution of effective therapeutic interventions as well as patient selection.

Final infarct volume is a stronger predictor of outcome than recanalization in patients with proximal middle cerebral artery occlusion treated with endovascular therapy

BACKGROUND AND PURPOSE

The rationale for recanalization therapy in acute ischemic stroke is to preserve brain through penumbral salvage and thus improve clinical outcomes. We sought to determine the relationship between recanalization, clinical outcomes, and final infarct volumes in acute ischemic stroke patients presenting with middle cerebral artery occlusion who underwent endovascular therapy and post-procedure magnetic resonance imaging.

METHODS

We identified 201 patients with middle cerebral artery occlusion. Patients with other occlusive lesions were excluded. Baseline clinical/radiological characteristics, procedural outcomes (including thrombolysis in cerebral infarction scores), clinical outcome scores (modified Rankin scores), and final infarct volumes on diffusion weighted imaging were retrospectively analyzed from a prospectively collected database. Favorable outcome is defined as 90-day modified Rankin score≤2.

RESULTS

Successful recanalization (thrombolysis in cerebral infarction grade 2b or 3) was achieved in 63.2% and favorable outcomes in 46% of cases. Mean infarct volume was 50.1 mL in recanalized versus 133.9 mL in non-recanalized patients (P<0.01) and 40.4 mL in patients with favorable outcomes versus 111.8 in patients with unfavorable outcomes (P<0.01). In multivariate analysis, thrombolysis in cerebral infarction≥2b, baseline National Institute of Health Stroke Scale, Alberta Stroke Program Early Computed Tomography scores, and age were identified as independent predictors of outcome. However, when infarct volumes were included in the analysis only final infarct volume and age remained significantly associated.

CONCLUSIONS

Successful recanalization leads to improved functional outcomes through a reduction in final infarct volumes. In our series, age and final infarct volume but not recanalization were found to be independent predictors of outcome, supporting the use of final infarct volume as surrogate marker of outcome in acute stroke trials.

[Diffusion-Weighted Imaging infarct volume and neurologic outcomes after ischemic stroke]

BACKGROUND

This study's purpose was to demonstrate a relationship between growth of stroke volume measured on Diffusion-Weighted MRI (DWI) at admission (baseline) and 24 hours later (follow-up) and functional outcome at 90 days evaluated by the modified Rankin Scale (mRS).

METHODS

DWI infarct volumes were calculated, using an Analyze Software. Clinical outcomes were assessed at 90 days by the mRS. Univariate regression analysis was performed to assess the relationship between changes in DWI lesion volume and mRS less or equal to 1.

RESULTS

Sixty-nine cases had serial DWI scans with a measurable lesion at baseline and follow-up. The median baseline National Institutes of Health Stroke Scale (NIHSS) was 10, 5 and 7 at 24 hours. At 90 days, the proportion of patients with Rankin less or equal to 1 was 51.7%. The average baseline volume was 19.7 cm(3) and average follow-up volume was 46.1 cm(3). For each 10 cm(3) of growth in DWI infarct volume, the odds ratio for a mRS less or equal to 1 was 10,1 (IC 95%, 3-33.9).

CONCLUSION

The results of this study provide evidence of a significant inverse relationship between infarct growth measured by DWI and good functional clinical outcome at 90 days.

WebParc: a tool for analysis of the topography and volume of stroke from MRI

The quantitative assessment of the anatomic consequences of cerebral infarction is critical in the study of the etiology and therapeutic response in patients with stroke. We present here an overview of the operation of "WebParc," a computational system that provides measures of stroke lesion volume and location with respect to canonical forebrain neural systems nomenclature. Using a web-based interface, clinical imaging data can be registered to a template brain that contains a comprehensive set of anatomic structures. Upon delineation of the lesion, we can express the size and localization of the lesion in terms of the regions that are intersected within the template. We demonstrate the application of the system using MRI-based diffusion-weighted imaging and document measures of the validity and reliability of its uses. Intra- and inter-rater reliability is demonstrated, and characterized relative to the various classes of anatomic regions that can be assessed. The WebParc system has been developed to meet criteria of both efficiency and intuitive operator use in the real time analysis of stroke anatomy, so as to be useful in support of clinical care and clinical research studies. This article is an overview of its base-line operation with quantitative anatomic characterization of lesion size and location in terms of stroke distribution within the separate gray and white matter compartments of the brain.

A simple scoring system for outcome prediction of ischemic stroke

OBJECTIVES

According to most existing models, a computer is usually needed for predicting stroke outcome. Our purpose was to construct a simple and reliable prognostic scale not requiring the use of a calculating machine.

MATERIALS AND METHODS

The scale [the Bologna Outcome Algorithm for Stroke (BOAS)] was obtained in 221 patients with ischemic stroke not undergoing thrombolysis and was then validated in a test group of 100 different patients. Outcome was assessed at 9 months as the number of dependent or dead patients (modified Rankin scale - mRS > 2).

RESULTS

By a preliminary systematic univariate analysis, 25 of 415 baseline variables were found to be associated with a mRS > 2 independently of stroke severity and age. Subsequent multivariable analyses led to a final model based on five dichotomous risk factors (RF): National Institutes of Health Stroke Scale score ≥10, age ≥78, need of urinary catheter, oxygen administration, and persistence of upper limb paralysis at discharge from stroke unit. The patients with two or more RF (53%) had a mRS > 2 in 91% of cases and were dead in 42% of cases. With 0-1 RF, the two percentages were 24% and 2%, respectively (overall accuracy of prediction 83.9%, area under ROC curve [AUC] 0.891). In the test group, the accuracy was 79.0% and the AUC was 0.839.

CONCLUSIONS

The need of urinary catheter, oxygen administration, and persistence of upper limb paralysis, together with stroke severity and advanced age, allow a simple and accurate prediction of dependency or death after ischemic stroke.

Functional imaging in muscular diseases

OBJECTIVE: The development of morphological and functional imaging techniques has improved the diagnosis of muscular disorders. METHODS: With the use of whole-body magnetic resonance imaging (MRI) the possibility of imaging the entire body has been introduced. In patients with suspected myositis, oedematous and inflammatory changed muscles can be sufficiently depicted and therefore biopsies become more precise. RESULTS: Functional MR methods visualise different aspects of muscular (patho)physiology: muscular sodium (Na(+)) homeostasis can be monitored with (23)Na MRI; the muscular energy and lipid metabolism can be monitored using (31)P and (1)H MR spectroscopy. (23)Na MRI has reached an acceptable value in the diagnosis and follow-up of patients with muscular Na(+) channelopathies that are characterised by myocellular Na(+) overload and consecutive muscle weakness. Besides MRI, low mechanical index contrast-enhanced ultrasound (CEUS) methods have also been introduced. For evaluation of myositis, CEUS is more efficient in the diagnostic work-up than usual b-mode ultrasound, because CEUS can detect the inflammatory-induced muscular hyperperfusion in acute myositis. Moreover, the arterial perfusion reserve in peripheral arterial disease can be adequately examined using CEUS. CONCLUSION: Modern muscular imaging techniques offer deeper insights in muscular (patho)physiology than just illustrating unspecific myopathic manifestations like oedematous or lipomatous changes, hypertrophy or atrophy.