Relationship between Presence of Visceral Infarction and Functional Outcome among Patients with Acute Ischemic Stroke.

INTRODUCTION: Evidence of visceral infarction is often found in patients with acute ischemic stroke. It remains uncertain whether there exists a relationship between visceral infarction and functional outcomes among patients with stroke. OBJECTIVE: The aim of this study was to evaluate whether evidence of visceral infarction is associated with functional outcomes among patients with stroke. METHODS: Among patients with acute ischemic stroke enrolled in the Cornell AcutE Stroke Academic Registry (CAESAR) from 2011 through 2016, we included those with a contrast-enhanced abdominal computed tomographic scan within 1 year of admission. Our outcome was ambulatory status at discharge from acute stroke hospitalization, categorized as walking without assistance, walking with assistance, and unable to walk. We used ordinal logistic regression to examine the association between visceral infarction and discharge ambulatory status after adjustment for demographics, stroke risk factors, stroke severity (NIH Stroke Scale), and stroke subtype. RESULTS: Among 2,116 ischemic stroke patients registered in CAESAR from 2011 to 2016, 259 had contrast-enhanced abdominal computed tomographic imaging, of whom 48 (19%) had evidence of visceral infarction. After adjustment for demographics, stroke risk factors, stroke severity, and stroke subtype, the presence of visceral infarction was associated with a worse ambulatory status at discharge (global OR for better ambulatory status, 0.4; 95% CI, 0.2-1.0, p = 0.046). CONCLUSIONS: We found that the presence of visceral infarction was associated with poor functional outcomes at the time of hospital discharge. These findings suggest that such findings are not necessarily benign and are at the least a marker of poor outcomes.

Association Between Troponin Levels and Visceral Infarction in Patients with Acute Ischemic Stroke.

BACKGROUND: Visceral infarctions appear to be more common in patients with embolic stroke subtypes, but their relation to troponin elevation remains uncertain. METHODS: Among patients with acute ischemic stroke enrolled in the Cornell AcutE Stroke Academic Registry (CAESAR) from 2011 to 2016, we included those with troponin measured within 24 hours from stroke onset and a contrast-enhanced abdominal computed tomographic scan within 1 year of admission. A troponin elevation was defined as a value exceeding our laboratory's upper limit of normal (.04 ng/ mL) in the absence of a clinically recognized acute ST-segment elevation myocardial infarction. Visceral infarction was defined as a renal or splenic infarction as ascertained by a single radiologist blinded to patients' other characteristics. Multivariable logistic regression was used to evaluate the association between elevated troponin and visceral infarction. RESULTS: Among 2116 patients registered in CAESAR from 2011 to 2016, 153 patients had both a troponin assay and a contrast-enhanced abdominal computed tomographic scan, of whom 33 (21%) had an elevated troponin and 22 (14%) had a visceral infarction. The prevalence of visceral infarction was higher among patients with an elevated troponin (30%; 95% confidence interval [CI], 16%-49%) than among patients without an elevated troponin (10%; 95% CI, 5%-17%) (P = .003). After adjustment for demographics and comorbidities, we found a significant association between elevated troponin and visceral infarction (odds ratio, 3.9; 95% CI, 1.5-10.4). CONCLUSIONS: Among patients with acute ischemic stroke, elevated troponin was associated with visceral infarction. Our results demonstrate that poststroke troponin elevation may indicate the presence of underlying embolic sources.

Effect of Clinical History on Interpretation of Computed Tomography for Acute Stroke.

OBJECTIVE: We assessed whether providing detailed clinical information alongside computed tomography (CT) images improves their interpretation for acute stroke. METHODS: Using the prospective Cornell AcutE Stroke Academic Registry, we randomly selected 100 patients who underwent noncontrast head CT within 6 hours of transient ischemic attack or minor acute ischemic stroke and underwent magnetic resonance imaging (MRI) within 6 hours of the CT. Three radiologist investigators evaluated each of the 100 CT studies twice, once with and once without accompanying information on medical history, signs, and symptoms. In random sequence, each study was interpreted in one condition (ie, with or without detailed accompanying information) and then after a 4-week washout period, in the opposite condition. Using MRI diffusion-weighted imaging (DWI) as the reference standard, we classified CT interpretations as correct (true positives or negatives) or incorrect (false positives or negatives). We used logistic regression with sandwich estimators to compare the proportion of correct interpretations. RESULTS: In patients with DWI-defined infarcts, acute ischemia was called on 20% of CTs with detailed history and 18% without history. In patients without infarcts, the absence of ischemia was called on 77% of CTs with history and 77% without history. The proportion of correct interpretations of CTs accompanied by detailed clinical history (49%) did not differ significantly from those without history (47%; odds ratio: 1.1; 95% confidence interval: 0.8-1.4). CONCLUSIONS: Reported findings on head CT for evaluation of suspected acute ischemic stroke were similar regardless of whether detailed clinical history was provided.

Association Between Carotid Artery Perivascular Fat Density and Cerebrovascular Ischemic Events.

Background Studies have shown that pericoronary artery inflammation can be accurately detected via increased attenuation on computed tomography. Our purpose was to evaluate the association between pericarotid inflammation, measured by density of carotid perivascular fat on computed tomography angiography, with stroke and transient ischemic attack. Methods and Results We screened computed tomography angiography examinations for patients with unilateral internal carotid artery ( ICA ) stenosis ≥50% to 99%. A blinded neuroradiologist placed regions-of-interest in the pericarotid fat on the slice showing maximal stenosis. Two-sample t tests were performed to assess between-subject differences in mean Hounsfield Units in carotid perivascular fat between symptomatic and asymptomatic patients. Paired t tests were used to assess within-subject differences in mean Hounsfield Units between stenotic versus nonstenotic ICA s in a given patient. We included 94 patients, including 42 symptomatic and 52 asymptomatic patients. In the between-subject analysis of stenotic ICA s, we found symptomatic patients had higher mean pericarotid fat density compared with asymptomatic patients (-66.2±19.2 versus -77.1±20.4, P=0.009). When comparing nonstenotic ICA s, there was no significant difference between pericarotid fat density in symptomatic compared with asymptomatic patients (-81.0±13.3 versus -85.3±18.0: P=0.198). Within-subject comparison showed statistically significant increased density in stenotic ICA versus nonstenotic ICA with mean Hounsfield Units difference of 11.1 ( P<0.0001). Conclusions We found increased density, a surrogate marker for perivascular inflammation, in the fat surrounding ICA s ipsilateral to stroke or transient ischemic attack compared with asymptomatic ICA s. Our findings suggest that inflammation associated with culprit carotid plaques extends beyond the vessel lumen and can be identified using simple methods on computed tomography angiography imaging.

Angiographic Blush after Mechanical Thrombectomy is Associated with Hemorrhagic Transformation of Ischemic Stroke.

BACKGROUND AND PURPOSE: Risk factors for hemorrhagic transformation of ischemic stroke after mechanical thrombectomy (MT) are not well established. We conducted a study to determine if prominent angiographic cerebral vascularity following recanalization with thrombectomy (angiographic blush) is associated with hemorrhagic transformation. METHODS: Using the Cornell AcutE Stroke Academic Registry, we identified stroke patients who had thrombectomy and achieved recanalization of anterior circulation large-vessel occlusion between 2012 and 2015. The exposure variable was presence of angiographic blush after recanalization, defined as capillary blush with or without early venous drainage. The primary outcome was volume of hemorrhagic transformation on brain imaging after thrombectomy, as determined by semiautomated volumetric analysis on computed tomography or magnetic resonance imaging among those adjudicated to have hemorrhagic conversion by neuroradiology investigators blinded to angiography results. Using a doubly robust estimator with propensity scores and outcome regression adjusting for demographics and known risk factors for hemorrhagic transformation, we evaluated whether angiographic blush after recanalization is associated with an increased volume of hemorrhagic transformation. RESULTS: Among 48 eligible patients, 31 (64.6%) had angiographic blush and 26 (54.2%) had radiographic hemorrhagic transformation (mean volume, 7.6 ml). Patients with angiographic blush averaged lower thrombolysis in cerebral infarction scores and more often received intravenous thrombolysis. In adjusted analysis, angiographic blush was associated with an increased volume of hemorrhagic transformation: mean volume, 10.3ml (95% CI, 3.7-16.9 ml) with blush versus 1.8ml (95% Confidence Interval (CII = Confidence Interval), 0.1-3.4 ml) without (P = .01). CONCLUSIONS: Presence of angiographic blush after MT was independently associated with the volume of hemorrhagic transformation.

Relationship Between Visceral Infarction and Ischemic Stroke Subtype.

BACKGROUND AND PURPOSE: Most cryptogenic strokes are thought to have an embolic source. We sought to determine whether cryptogenic strokes are associated with visceral infarcts, which are usually embolic. METHODS: Among patients prospectively enrolled in CAESAR (Cornell Acute Stroke Academic Registry), we selected those with a contrast-enhanced abdominal computed tomographic scan within 1 year of admission. Our exposure variable was adjudicated stroke subtype per the Trial of ORG 10172 in Acute Stroke Treatment classification. Our outcome was renal or splenic infarction as assessed by a single radiologist blinded to stroke subtype. We used Fisher exact test and multiple logistic regression to compare the prevalence of visceral infarcts among cardioembolic strokes, strokes of undetermined etiology, and noncardioembolic strokes (large- or small-vessel strokes). RESULTS: Among 227 patients with ischemic stroke and a contrast-enhanced abdominal computed tomographic scan, 59 had a visceral infarct (35 renal and 27 splenic). The prevalence of visceral infarction was significantly different among cardioembolic strokes (34.2%; 95% confidence interval [CI], 23.7%-44.6%), strokes of undetermined etiology (23.9%; 95% CI, 15.0%-32.8%), and strokes from large-artery atherosclerosis or small-vessel occlusion (12.5%; 95% CI, 1.8%-23.2%; P=0.03). In multiple logistic regression models adjusted for demographics and vascular comorbidities, we found significant associations with visceral infarction for both cardioembolic stroke (odds ratio, 3.5; 95% CI, 1.2-9.9) and stroke of undetermined source (odds ratio, 3.3; 95% CI, 1.1-10.5) as compared with noncardioembolic stroke. CONCLUSIONS: The prevalence of visceral infarction differed significantly across ischemic stroke subtypes. Cardioembolic and cryptogenic strokes were associated with a higher prevalence of visceral infarcts than noncardioembolic strokes.

MR perfusion-weighted imaging in the evaluation of high-grade gliomas after treatment: a systematic review and meta-analysis.

BACKGROUND: Distinction between tumor and treatment related changes is crucial for clinical management of patients with high-grade gliomas. Our purpose was to evaluate whether dynamic susceptibility contrast-enhanced (DSC) and dynamic contrast enhanced (DCE) perfusion-weighted imaging (PWI) metrics can effectively differentiate between recurrent tumor and posttreatment changes within the enhancing signal abnormality on conventional MRI. METHODS: A comprehensive literature search was performed for studies evaluating PWI-based differentiation of recurrent tumor and posttreatment changes in patients with high-grade gliomas (World Health Organization grades III and IV). Only studies published in the "temozolomide era" beginning in 2005 were included. Summary estimates of diagnostic accuracy were obtained by using a random-effects model. RESULTS: Of 1581 abstracts screened, 28 articles were included. The pooled sensitivities and specificities of each study's best performing parameter were 90% and 88% (95% CI: 0.85-0.94; 0.83-0.92) and 89% and 85% (95% CI: 0.78-0.96; 0.77-0.91) for DSC and DCE, respectively. The pooled sensitivities and specificities for detecting tumor recurrence using the 2 most commonly evaluated parameters, mean relative cerebral blood volume (rCBV) (threshold range, 0.9-2.15) and maximum rCBV (threshold range, 1.49-3.1), were 88% and 88% (95% CI: 0.81-0.94; 0.78-0.95) and 93% and 76% (95% CI: 0.86-0.98; 0.66-0.85), respectively. CONCLUSIONS: PWI-derived thresholds separating viable tumor from treatment changes demonstrate relatively good accuracy in individual studies. However, because of significant variability in optimal reported thresholds and other limitations in the existing body of literature, further investigation and standardization is needed before implementing any particular quantitative PWI strategy across institutions.

Diffusion Weighted/Tensor Imaging, Functional MRI and Perfusion Weighted Imaging in Glioblastoma-Foundations and Future.

In this article, we review the basics of diffusion tensor imaging and functional MRI, their current utility in preoperative neurosurgical mapping, and their limitations. We also discuss potential future applications, including implementation of resting state functional MRI. We then discuss perfusion and diffusion-weighted imaging and their application in advanced neuro-oncologic practice. We explain how these modalities can be helpful in guiding surgical biopsies and differentiating recurrent tumor from treatment related changes.