Diffusion-weighted Imaging Infarct Volume Research Articles

Association of Bun/Cr ratio-based dehydration status with infarct volumes and stroke severity in acute ischemic stroke

BackgroundOnly a few clinical research had previously investigated the dehydration status to predict the evolution of the ischemic core. The aim of this study is to clarify the association between blood urea nitrogen (BUN)/creatinine (Cr)ratio-based dehydration and infarct volume measured using DWI (Diffusion-weighted imaging) at admission in patients with AIS (Acute Ischemic Stroke). MethodsWe retrospectively recruited a total of 203 consecutive patients who were hospitalized through emergency or outpatient services within 72 h of acute ischemic stroke onset between October 2015 and September 2019. Stroke severity was measured by assessing the National Institutes of Health Stroke Scale (NIHSS) on admission. Infarct volume was measured using DWI with MATLAB software. ResultsIn this study, 203 patients who met the study criteria were enrolled. Patients in the dehydration group (Bun/Cr ratio>15) had a higher median NIHSS score (6(IQR:4–10) VS. 5(3−7); P = 0.0015)and larger DWI infarct volume (1.55 ml (IQR:0.51–6.79) VS. (0.37 ml (0.05–1.22); P < 0.001) on admission compared with patients in normal group. Further, a statistically significant correlation was found between DWI infarct volumes and NIHSS score with nonparametric Spearman rank correlation (r = 0.77; P < 0.001). The median NIHSS scores for the DWI infarct volumes quartiles were 3 ml (IQR, 2–4), 5 ml (4−7), 6 ml (5−8), and12 ml (8−17) from lowest to highest. However, the second quartile group did not show any significant correlation with the third quartile group (P = 0.4268). Multivariable linear and logistic regression analyses were used to test dehydration (Bun/Cr ratio>15), representing a predictor of infarct volume and stroke severity. ConclusionBun/Cr ratio-based dehydration is associated with larger volumes of ischemic tissue measured using DWI and worse neurological deficit assessed by the NIHSS score in acute ischemic stroke.

Association of serum calcium levels with infarct volume and stroke scores in acute ischemic stroke patients: An observational study.

Stroke vastly contributes to death and disability worldwide. Acute ischemic stroke (AIS) is caused by a reduction in supply of blood to the brain. Accumulation of unnecessary intracellular serum calcium in AIS induces the cytotoxic actions that activates enzymes involved in cell death. The present investigation assessed the relationship of total serum calcium level (at admission) and initial diffusion weighted imaging (DWI) infarct volume and correlated with National Institute of Health Stroke Scale (NIHSS) scores. A hospital-based observational study was conducted on 74 consecutive patients identified with AIS fulfilling the inclusion criteria. NIHSS scores and serum ionized calcium were calculated in every patient and compared with DWI infarct volume for assessing correlation between these three. Statistical software R Version 4.0.2 and Microsoft Excel were used for statistical analysis. Out of the 74 patients, most of them were in age group of 50-69 years, with a male preponderance (68.9%). A significant association was noticed between diabetes and dyslipidemia with age (P=0.01499). A strong negative correlation was observed between NIHSS scores (at admission & discharge) with ionized calcium, while a strong positive correlation was noticed between stroke scores with infarct volume. A statistically significant negative correlation was recorded between serum calcium (on admission) and infarct size (r=-0.851755, P=0.0001). The mean of NIHSS scores on admission (8.24±5.19) has been remarkably higher when compared with NIHSS scores at discharge (5.25±3.89). In patients with AIS examined within 6-24 hours of symptoms onset, serum ionized calcium and volume of infarct on DWI showed inverse association. Serum calcium serves as a marker of severity and acts as prognostic factor in AIS.

The Degree of Plasma Oxidized Low-Density Lipoprotein Level Decrease Is Related to Clinical Outcomes for Patients with Acute Ischemic Stroke.

Objective To investigate the relationship between the decrease of plasma oxidized low-density lipoprotein (oxLDL) levels and clinical outcomes in patients with acute atherosclerosis-related ischemic stroke. Methods We recruited acute ischemic stroke patients within 3 days of onset consecutively. Plasma oxLDL levels were measured on the second day after admission and before discharge (10-14 days after stroke onset). Initial stroke severity was assessed by the National Institutes of Health Stroke Scale (NIHSS) scores, and infarct volume was measured using diffusion-weighted imaging (DWI) by the ITK-SNAP software. Clinical outcomes were evaluated by DWI volumes in the acute phase, neurological improvement at discharge, and favorable functional prognosis at 90 days. Logistic regression was performed to evaluate the association between oxLDL level decrease and clinical outcomes. Results 207 patients were enrolled in this study. Compared with the mild decrease of the oxLDL level group, patients with a significant decrease of the oxLDL level group were more likely to have a higher ratio of neurological improvement at discharge (55.07% vs. 14.49%, p < 0.01) and favorable functional prognosis at 90 days (91.30% vs. 55.07%, p < 0.01). In multivariable logistic regression, the degree of oxLDL level decrease was related to neurological improvement at discharge and favorable functional prognosis at 90 days (p < 0.01). Patients with significant decrease were more likely to have neurological improvement at discharge (OR = 7.92, 95% CI, 3.14-19.98, and p < 0.01) and favorable functional prognosis at 90 days (OR = 7.46, 95% CI, 2.40-23.23, and p < 0.01) compared to patients with mild decrease of oxLDL level. The DWI volumes in patients with different oxLDL level decrease groups had no statistical difference (p = 0.41), and the Spearman's rho between oxLDL level decrease and DWI infarct volumes was -0.03, but no statistical difference (p = 0.72). Conclusions The degree of oxLDL level decrease is related to neurological improvement at discharge and favorable functional prognosis at 90 days for patients with acute atherosclerosis-related ischemic stroke, but not with infarct volume in the acute phase.

Extent of white matter lesion is associated with early hemorrhagic transformation in acute ischemic stroke related to atrial fibrillation.

BackgroundHemorrhagic transformation (HT) after stroke, related to atrial fibrillation (AF), is a frequent complication, and it can be associated with a delay in the (re‐)initiation of oral anticoagulation therapy. We investigated the effect of the presence and severity of white matter disease (WMD) on early HT after stroke related to AF.MethodsA consecutive series of patients with recent (<4 weeks) ischemic stroke and AF, treated at the Hyper Acute Stroke Unit of the Imperial College London between 2010 and 2017, were enrolled. Patients with brain MRI performed 24–72 h from stroke onset and not yet started on anticoagulant treatment were included. WMD was graded using the Fazekas score.ResultsAmong the 441 patients eligible for the analysis, 91 (20.6%) had any HT. Patients with and without HT showed similar clinical characteristics. Patients with HT had a larger diffusion‐weighted imaging (DWI) infarct volume compared to patients without HT (p < .001) and significant difference in the distribution of the Fazekas score (p = .001). On multivariable analysis, HT was independently associated with increasing DWI infarct volume (odd ratio (OR), 1.03; 95% confidence interval (CI), 1.01–1.05; p < .001), higher Fazekas scores (OR, 1.94; 95% CI, 1.47–2.57; p < .001) and history of previous intracranial hemorrhage (OR, 4.80; 95% CI, 1.11–20.80; p = .036).ConclusionsPresence and severity of WMD is associated with increased risk of development of early HT in patients with stroke and AF. Further evidence is needed to provide reliable radiological predictors of the risk of HT in cardioembolic stroke.

Early Neurological Deterioration and Hypoperfusion Volume Ratio on Arterial Spin Labeling in Patients with Acute Ischemic Stroke

BackgroundArterial spin labeling (ASL) is a magnetic resonance imaging (MRI) technique used to quantify cerebral blood perfusion by labeling blood water as it flows throughout the brain. Hypoperfusion volume ratio (HVR) can be calculated using proportional hypoperfusion volume on ASL-based cerebral blood flow (CBF). This study aimed to explore the relation between HVR and early neurological deterioration (END) in AIS patients. Subjects and MethodsPatients with AIS were recruited consecutively, and ASL and regular MRI scans were performed. HVR was calculated from 1.5 and 2.5s post labeling delay (PLD) ASL-CBF maps. END was defined as ≥2 points increment of NIHSS within 72 hours of stroke onset. Univariate and multivariate analysis were used to evaluate the relation between HVR and END. Receiver operating characteristic (ROC) curves were used to determine the ability of HVR in predicting END. ResultsOf the 52 enrolled patients, 18 (34.5%) were determined with END. In patients with END, the median hypoperfusion volume was 20 mL [Inter Quartile Range)IQR, 6-72.5 mL] at 1.5s PLD, and 11.2 mL (IQR, 5.3-26 mL) at 2.5s PLD; Sixteen (88.9%) patients had HVR ≥50%, and 13 (72.2%) patients hypoperfusion volume at 2.5s PLD ASL were greater than diffusion-weighted imaging (DWI) infarct volume. In patients without END, median hypoperfusion volume was 7 mL (IQR, 4-30 mL) at 1.5s PLD, and 4 mL (IQR, 1.5-8.5 mL) at 2.5s; Eleven (32.4%) patients had HVR ≥50%, and 10 (29.4%) patients hypoperfusion volume at 2.5s PLD ASL were greater than DWI infarct volume. The proportion of HVR ≥50% and hypoperfusion volume >DWI infarct volume were more frequent in patients with END than patients without (all P<0.001). After adjusted for age, admission NIHSS, proportion of hypoperfusion volume > DWI infarct and arterial transit artifact (ATA) by logistic regression analysis, HVR ≥50% (OR=13.1, P=0.003) was an independent risk factor for END. ROC analysis demonstrated that the HVR could predict END with an area under the curve of 0.794 (P=0.001). ConclusionsHVR obtained from the 1.5 and 2.5s PLD ASL may be a useful predictor of END in AIS. The value of HVR may be a marker for hemodynamic impairments.

A Volumetric Comparison of Computed Tomography Perfusion RAPID Core Volume in Different Time Frames with Diffusion-Weighted Imaging Infarct Volume in the Post-Thrombectomy Patients after Anterior Circulation Large Vessel Occlusion (2315)

A Volumetric Comparison of Computed Tomography Perfusion RAPID Core Volume in Different Time Frames with Diffusion-Weighted Imaging Infarct Volume in the Post-Thrombectomy Patients after Anterior Circulation Large Vessel Occlusion (2315)

Abstract P362: A Volumetric Comparison of Computed Tomography Perfusion Rapid Core Volume in Different Time Frames With Diffusion-Weighted Imaging Infarct Volume in the Post-Thrombectomy Patients After Large Vessel Occlusion

Introduction: The Computed Tomography Perfusion (CTP) RAPID software is widely used for the patient selection for mechanical thrombectomy (MT) after anterior circulation large vessel occlusion (LVO). There is a notion that it overestimates the core volume (CV) in an earlier time frame from symptom onset. We compared the accuracy of CTP RAPID estimated CV in different time frames with diffusion weighted imaging (DWI) infarct volume (IV). Method: A retrospective data review of patients who underwent MT for anterior circulation LVO with TICI 2b/3 reperfusion from 2017 to 2019 was done. Patients with baseline CTP and follow up 36-hour MRI was included. Patients with parenchymal hematoma, graded as per ECASS II classification were excluded. CTP time was dichotomized as 0-3 hours (hrs) and &gt;3 hrs from symptom onset. DWI IV was calculated by ABC/2 formula. The volumetric difference (VD), defined as DWI IV minus CTP CV, core volume overestimation (CVO), defined as CTP CV minus DWI IV and CT ASPECTS was calculated. Large CV was defined as &gt;50 ml CV. Standard descriptive statistics and independent sample T-test were used as statistical tools. Result: Total MT cases (n) were 61. Mean age (y.o) was 66 (SD 13.9) (male 57.4%). In &lt; 3 hrs from symptom onset (n 27), mean CTP CV was 38.8 ml (SD 39.8), DWI IV was 39.6 ml (SD 51.4), VD was 0.9 ml (SD 55.2) (p 0.945) and CVO (n 11) was 39.6 ml (SD 35.7) (p 0.008). Mean large CV (n 8) was 78.3 ml (SD 25.4) with median CT ASPECTS of 8 (IQR 6.5-9) and median mRS at discharge 2 (IQR 0.8- 3.3). In &gt;3 hrs from symptom onset (n 34), mean CTP CV was 28.81 ml (SD 47.4), DWI IV was 75.3 ml (SD 69.5), VD was 46.5 ml (SD 61.8) (p 0.002) and CVO (n 5) was 25.2 ml (SD 41.27) (p 0.60). Mean large CV (n 5) was 116.8 ml (SD 75.3) with median CT ASPECTS of 6 (IQR 5-7) and median mRS at discharge 5 (IQR 4- 6). Conclusion: Overestimated core volume on CTP was seen in more than one third cases within 3 hours from symptom onset. Large CV estimated within this time frame had higher CT ASPECTS and good functional outcome at discharge.

Use of the ABC/2 Method to Select Patients for Thrombectomy After 6 Hours of Symptom Onset.

To determine whether the ABC/2 method could accurately and reliably measure infarct volume and guide thrombectomy decision in acute stroke cases presenting with late or unknown onset. Four physicians who routinely use MRI for acute stroke imaging, blinded to the RAPID results, measured the diffusion-weighted imaging (DWI) infarct volume using the ABC/2 method. Measurements with ABC/2 (the index test) were compared with RAPID (the reference standard) to calculate sensitivity, specificity, and accuracy measures for various volume cutpoints. Thrombectomy decisions based on RAPID and raters' measurements using the criteria from the Diffusion-Weighted Imaging or Computerized Tomography Perfusion Assessment With Clinical Mismatch in the Triage of Wake-Up and Late-Presenting Strokes Undergoing Neurointervention With Trevo (DAWN) trial criteria were compared. Interrater and intrarater agreement was measured using kappa statistics. Accuracy with the ABC/2 method was greater than 80% for each rater and each volume cut point. Interrater and intrarater agreement was substantial to excellent for each volume cut point. Treatment decisions with ABC/2 volume estimations showed strong interrater and intrarater agreement, and led to similar thrombectomy decisions compared with RAPID in more than 85% of cases. DWI infarct volume measurement using ABC/2 method shows strong accuracy and reliability and may be an acceptable alternative to RAPID software for the application of DAWN criteria for thrombectomy decision-making.

Diffusion-Weighted-Imaging infarct volume measurement tools show discrepancies leading to diverging thrombectomy decisions

Background and purposeRecent clinical trials demonstrated the benefit of thrombectomy beyond 6h based on the automated measurement of infarct volume exclusively with the RAPID software. We aimed to compare eight tools commonly used for the measurement of infarct volume and see whether they would lead to similar thrombectomy decisions based on the Diffusion-weighted-imaging or computerized-tomography-perfusion Assessment with clinical mismatch in the triage of Wake-up and late-presenting strokes undergoing Neurointervention with Trevo (DAWN) trial imaging inclusion criteria. Materials and MethodsThe diffusion-weighted-imaging (DWI) infarct volume of 36 patients was measured with 3 automated tools (including RAPID) and 5 non-automated tools. The agreement for the measurements of DWI infarct volume and the resulting thrombectomy decisions were assessed with intraclass correlation coefficient (ICC) and Fleiss’ Kappa (K) statistics. ResultsThe correlation for the measurement of DWI infarct volume between all 9 tools was excellent (ICC>0.8). After dichotomization, agreement was substantial for any of the cut-points used in DAWN trial. Discrepancies involving at least one of the tools for thrombectomy decisions based on DAWN criteria occurred in one third of cases. Compared with RAPID, the use of any other tool for treatment decision based on DAWN criteria would have led to contradictory decisions in 6% to 19% of cases. ConclusionThere are several currently available tools for the measurement of DWI infarct volume with excellent correlation. Despite the high agreement demonstrated in our study, frequent discrepancies between measurements in some dichotomized configurations led to frequent diverging thrombectomy decisions when applying DAWN criteria.

Visual assessment of diffusion weighted imaging infarct volume lacks accuracy and reliability

PurposeThe DAWN trial (Diffusion weighted imaging or CT perfusion Assessment with clinical mismatch in the triage of Wake-up and late presenting strokes undergoing Neurointervention with Trevo) has demonstrated the benefits...

Association of Serum 25(OH) D Levels with Infarct Volumes and Stroke Severity in Acute Ischemic Stroke.

The aim of this study is to investigate whether 25-hydroxyvitamin D [25(OH) D] is associated with initial stroke severity and infarct volume, using diffusion-weighted imaging (DWI) in patients with acute ischemic stroke. We studied a total of 235 patients who were admitted within 24 hours of acute ischemic stroke onset. Initial stroke severity was assessed using the NIH Stroke Scale (NIHSS) score. Infarct volume was measured using DWI. Multivariable linear and logistic regression analyses were used to test whether 25(OH) D represents an independent predictor of infarct volume and stroke severity (NIHSS score of ≥6). Among 235 study patients, the median age was 64 years (IQR 56-75 years), and 125 (53.2%) were women. In multivariable models adjusted for other significant risk factors, 25(OH) D levels in the lowest and second interquartiles were associated with an increased risk of a NIHSS≥6 (with highest 25 (OH) D quartile as reference) with odd ratios (OR) 3.02(95% confidence interval [CI]:1.59-6.34) and 5.85(2.90-11.54). The median DWI infarct volumes for the serum 25(OH) D level quartiles (lowest to highest) were 12.35, 6.55, 2.44, and 1.59 ml. The median DWI infarct volume in the lowest serum 25(OH) D level quartile was larger than that in the other 3 quartiles (P<0.001). The median adjusted DWI infarct volume in the lowest serum 25(OH) D level quartile was statistically significantly larger than that in the other 3 quartiles (P<0.01). In conclusion, reduced serum 25(OH) D levels in acute ischemic stroke are an early predictor of larger volumes of ischemic tissue and worse neurological deficit (assessed by the NIHSS).

Biochemical aspirin resistance is associated with increased stroke severity and infarct volumes in ischemic stroke patients.

To explore the correlation of aspirin resistance (AR) with clinical stroke severity and infarct volume using diffusion-weighted imaging (DWI) in 224 Chinese ischemic stroke patients who were taking aspirin before stroke onset. In those patients, the median age was 64 years (IQR, 56-75 years), and males accounting for 54.9%(123)of the total subjects. Fifty of 224 enrolled patients (22.3%; 95% confidence interval (CI), 16.9% to 27.7%) showed AR. In the median regression model, significant increase was estimated in NIHSS score of 0.04 point for every 1-point increase in aspirin reaction units (ARU) (95% CI, 0.02 to 0.06; P<0.001). Diffusion-weighted MRI (DWI)-measured infarct volume were significantly higher in patients with AR as compared with those with AS [13.21 (interquartile ranges [IQR], 8.51-23.88) vs.4.26 (IQR, 1.74-11.62); P<0.001). Furthermore, a statistically significant increase was also measured in NIHSS score of 0.05 point for every 1-point increase in ARU in the median regression model (95% CI, 0.03 to 0.08; P<0.001). The median DWI infarct volume was significantly larger in the highest ARU quartile when compared to that in the low 3 quartiles (P<0.001). In conclusion, stroke patients with AR indicated higher risk of severe strokes and large infarcts compared to patients in the aspirin-sensitive group.

Renal Impairment and Infarct Volume in Ischemic Stroke

Background The decreased estimated glomerular filtration rate (eGFR) levels at admission in patients with stroke have been associated with more severe clinical deficits and with worse outcomes; however, the relationship between eGFR levels and volumetric measurement of cerebral infarct size on neuroimaging has not been studied, to our knowledge. Methods Consecutive patients who presented within 48h of ischemic stroke and underwent brain diffusion-weighted imaging (DWI) over a 55-month period were studied. Patients with ischemic stroke of large artery atherosclerosis (LAA), small vessel occlusion (SVO), or cardioembolism (CE) etiologies were included. Those who were treated with thrombolysis and disabled before index stroke were excluded. Infarction volumes were log transformed to approximate normality. Chronic kidney disease (CKD) was defined as an eGFR < 60 mL/min per 1.73 m2. Subjects were categorized into two groups: CKD or no CKD. The relationship between CKD and DWI infarct volumes was examined using an analysis of covariance. Results Of the included 405 patients (mean age, 68 years; female, 60.2%; LAA, 60.0%; SVO, 16.5%; CE, 23.5%), 108 patients had CKD. Infarct volumes (mL, median [interquartile range]) were not significantly different between stroke patients with CKD and those without CKD in any stroke subtype (LAA, 0.77 [0.01-2.97] vs. 0.96 [0.01-5.22]; SVO, 0.18 [0.02-0.21] vs. 0.27 [0.01-0.52]; CE, 8.91 [0.04-28.54] vs. 5.22 [0.05-42.39]). Adjustment for possible confounders did not change the associations. Conclusion Renal impairment is not associated with cerebral infarct volume among acute ischemic stroke patients. Key Words: Renal impairment, Infarct volume

Aspirin resistance is associated with increased stroke severity and infarct volume.

To investigate whether aspirin resistance is associated with initial stroke severity and infarct volume, using diffusion-weighted imaging (DWI) in patients with acute ischemic stroke that occurred while taking aspirin. We studied a total of 310 patients who were admitted within 48 hours of acute ischemic stroke onset. All patients had been taking aspirin for at least 7 days before stroke onset. Aspirin resistance, defined as high residual platelet reactivity (HRPR) on aspirin treatment, was measured using the VerifyNow assay and defined as an aspirin reaction unit ≥550. Initial stroke severity was assessed using the NIH Stroke Scale (NIHSS) score. Infarct volume was measured using DWI. HRPR occurred in 86 patients (27.7%). The initial NIHSS score (median [interquartile range]) was higher in patients with HRPR than in the non-HRPR group (6 [3-15] vs 3 [1-8], p < 0.001). DWI infarct volumes were also larger in the HRPR group compared to the non-HRPR group (5.4 [0.8-43.2] vs 1.7 [0.4-10.3], p = 0.002). A multivariable median regression analysis showed that HRPR was significantly associated with an increase of 2.1 points on the NIHSS (95% confidence interval 0.8-4.0, p < 0.001) and an increase of 2.3 cm(3) in DWI infarct volume (95% confidence interval 0.4-3.9, p < 0.001). Aspirin resistance is associated with an increased risk of severe stroke and large infarct volume in patients taking aspirin before stroke onset.

Abstract WMP78: Follow-up High-Sensitivity C-reactive Protein is Associated With Early Recurrent Ischemic lesions in Acute Ischemic Stroke

Background: Early recurrent ischemic lesions (ERILs) on diffusion-weighted imaging (DWI) after acute ischemic stroke have been considered as a potential marker of early recurrent symptomatic stroke. The aim of this study to explore the impact of High-sensitivity C-reactive protein (hsCRP) levels at different time points on ERILs. Method: We prospectively enrolled 484 patients with acute ischemic stroke who underwent DWI and whose plasma and serum biomarkers (hsCRP, D-dimer, and brain natriuretic protein [BNP]) within 24 hours of onset and subsequently at 7 days after onset. Baseline characteristics, stroke features, initial National Institutes of Health Stroke Scale (NIHSS) score, and DWI lesion volume were recorded. ERILs were defined as new ischemic lesions on 7-day DWI, which were outside the vascular territory of index stroke with arterial occlusion and the same or outside the vascular territory of index stroke with arterial stenosis. Results: ERILs were observed in 146 patients (30.2%). In univariate analysis, atrial fibrillation (p=0.040), higher initial NIHSS score (p&lt;0.001), larger DWI infarct volume (p&lt;0.001), stroke subtype (p&lt;0.001), elevated initial and follow-up BNP (p=0.014 and p=0.003) and D-dimer (p=0.009 and p=0.011), and elevated follow-up hsCRP (p&lt;0.001) were positively associated and combination of anticoagulation and antiplatelet therapy after admission (p=0.002) was negatively associated with ERILs. In multivariate analysis, combination of anticoagulation and antiplatelet therapy after admission (Odds ratio [OR], 0.462; 95% confident interval [CI], 0.272 to 0.785; p=0.004) and follow-up log hsCRP (OR, 1.389; 95% CI, 1.054 to 1.830; p=0.020) were independent predictors of ERILs. Conclusions: Underlying inflammation after acute ischemic stroke may be associated with ERILs.

Comparison of CT perfusion summary maps to early diffusion-weighted images in suspected acute middle cerebral artery stroke

ObjectivesTo assess the accuracy and reliability of one vendor's (Vital Images, Toshiba Medical, Minnetonka, MN) automated CT perfusion (CTP) summary maps in identification and volume estimation of infarcted tissue in patients with acute middle cerebral artery (MCA) distribution infarcts. Subjects and methodsFrom 1085 CTP examinations over 5.5 years, 43 diffusion-weighted imaging (DWI)-positive patients were included who underwent both CTP and DWI <12h after symptom onset, with another 43 age-matched patients as controls (DWI-negative). Automated delay-corrected postprocessing software (DC-SVD) generated both infarct “core only” and “core+penumbra” CTP summary maps. Three reviewers independently tabulated Alberta Stroke Program Early CT scores (ASPECTS) of both CTP summary maps and coregistered DWI. ResultsOf 86 included patients, 36 had DWI infarct volumes ≤70ml, 7 had volumes >70ml, and 43 were negative; the automated CTP “core only” map correctly classified each as >70ml or ≤70ml, while the “core+penumbra” map misclassified 4 as >70ml. There were strong correlations between DWI volume with both summary map-based volumes: “core only” (r=0.93), and “core+penumbra” (r=0.77) (both p<0.0001). Agreement between ASPECTS scores of infarct core on DWI with summary maps was 0.65–0.74 for “core only” map, and 0.61–0.65 for “core+penumbra” (both p<0.0001). Using DWI-based ASPECTS scores as the standard, the accuracy of the CTP-based maps were 79.1–86.0% for the “core only” map, and 83.7–88.4% for “core+penumbra.” ConclusionAutomated CTP summary maps appear to be relatively accurate in both the detection of acute MCA distribution infarcts, and the discrimination of volumes using a 70ml threshold.

Final infarct volume estimation on 1-week follow-up MR imaging is feasible and is dependent on recanalization status.

PurposeWe aim to characterize infarct volume evolution within the first month post-ischemic stroke and to determine the effect of recanalization status on early infarct volume estimation.MethodsIschemic stroke patients recruited for the MONITOR and VISION studies were retrospectively screened and patients who had infarcts on diffusion-weighted imaging (DWI) at baseline and had at least two follow-up MR scans (n = 56) were included. Pre-defined target imaging time points, obtained on a 3-T MR scanner, were 12 hours (h), 24 h, 7 days, and ≥30 days post-stroke. Infarct tissue was manually traced blinded to the images at the other time points. Infarct expansion index was calculated by dividing infarct volume at each follow-up time point by the baseline DWI infarct volume. Recanalization was assessed within 24 h post-stroke. Correlation and statistical comparison analysis were done using the Spearman, Mann–Whitney, and Kruskal–Wallis tests.ResultsFollow-up infarct volumes were positively correlated with the baseline infarct volume (ρ > 0.81; p < 0.001) where the strongest correlation existed between baseline and 7-day post-stroke infarct volumes (ρ = 0.92; p < 0.001). The strongest correlation among the follow-up imaging was found between infarct volumes 7-day post-stroke and ≥30-day time points (ρ = 0.93; p < 0.001). Linear regression showed a close-to unity slope between 7-day and final infarct volumes (slope = 1.043; p < 0.001). Infarct expansion was higher in the non-recanalized group than the recanalized group at the 7-day (p = 0.001) and ≥30-day (p = 0.038) time points.ConclusionsFinal infarct volume can be approximated as early as 7 days post-stroke. Final infarct volume approximation is significantly associated with recanalization status.

Hypoperfusion Intensity Ratio Predicts Infarct Progression and Functional Outcome in the DEFUSE 2 Cohort

We evaluate associations between the severity of magnetic resonance perfusion-weighted imaging abnormalities, as assessed by the hypoperfusion intensity ratio (HIR), on infarct progression and functional outcome in the Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution Study 2 (DEFUSE 2). Diffusion-weighted magnetic resonance imaging and perfusion-weighted imaging lesion volumes were determined with the RAPID software program. HIR was defined as the proportion of TMax >6 s lesion volume with a Tmax >10 s delay and was dichotomized based on its median value (0.4) into low versus high subgroups as well as quartiles. Final infarct volumes were assessed at day 5. Initial infarct growth velocity was calculated as the baseline diffusion-weighted imaging (DWI) lesion volume divided by the delay from symptom onset to baseline magnetic resonance imaging. Total Infarct growth was determined by the difference between final infarct and baseline DWI volumes. Collateral flow was assessed on conventional angiography and dichotomized into good and poor flow. Good functional outcome was defined as modified Rankin Scale ≤2 at 90 days. Ninety-nine patients were included; baseline DWI, perfusion-weighted imaging, and final infarct volumes increased with HIR quartiles (P<0.01). A high HIR predicted poor collaterals with an area under the curve of 0.73. Initial infarct growth velocity and total infarct growth were greater among patients with a high HIR (P<0.001). After adjustment for age, DWI volume, and reperfusion, a low HIR was associated with good functional outcome: odds ratio=4.4 (95% CI, 1.3-14.3); P=0.014. HIR can be easily assessed on automatically processed perfusion maps and predicts the rate of collateral flow, infarct growth, and clinical outcome.

Hemoglobin A1C is independently associated with severity and prognosis of brainstem infarctions

ObjectiveTo assess the association of Hemoglobin A1C (HbA1c) with acute brainstem infarctions (BSIs) and to determine whether HbA1c is an independent risk factor in BSIs patients. Methods96 only BSIs patients were categorized into four groups according to HbA1c as <6%, ≥6% but <7%, ≥7% but <8%, or≥8%, respectively. The association of the four HbA1c groups with diffusion-weighted imaging (DWI) infarct volumes (DIV), National Institutes of Health Stroke Scale (NIHSS), and follow-up modified Rankin Scale (FmRS) scores were analyzed. Patients also were categorized into two groups according to HbA1c<6% or ≥6%. Logistic regression analyses were performed to determine independent risk factors. ResultsThere was a significant correlation between HbA1c and DIV (Spearman ρ=0.339, P=0.001), NIHSS scores (ρ=0.292, P=0.004) and FmRS scores (ρ=0.315, P=0.002). The incidence of pons infarction was highest in BSIs and patients with HbA1c≥6% showed significantly more frequent isolated pontine infarction. Logistic regression analyses showed that only HbA1c was independently associated with larger DIV (P=0.025) and FmRS scores (P=0.026). ConclusionsThese results suggest that elevated HbA1c level may be a potential serologic marker in the evaluation of the severity and prognosis of acute BSIs. There is an urgent need to study control of diabetes mellitus (DM) before and after BSIs.

Assessing Response to Stroke Thrombolysis

Imaging is used as a surrogate for clinical outcome in early-phase stroke trials. Assessment of infarct growth earlier than the standard 90 days used for clinical end points may be equally accurate and more practical. To compare assessment of the effect of reperfusion therapies using 24-hour vs day 90 magnetic resonance imaging. Infarct volume was assessed on diffusion-weighted imaging (DWI) at baseline and 24 hours after stroke onset and on fluid-attenuated inversion recovery images at day 90. The DWI and fluid-attenuated inversion recovery lesions were manually outlined by 2 independent raters, and the volumes were averaged. Interrater consistency was assessed using the median difference in lesion volume between raters. Referral center. Patients Imaging data were available for 83 patients; 77 of these patients received thrombolysis. Infarct volume at 24 hours and 90 days. The 24-hour DWI infarct volume had a strong linear correlation with day 90 fluid-attenuated inversion recovery infarct volume (r=0.98, 95% confidence interval, 0.97-0.99). Recanalization had a significant effect on infarct evolution between baseline and 24 hours but not between 24 hours and day 90. Infarct growth from baseline was significantly reduced by recanalization, whether assessed at 24 hours or day 90. Infarct volume at either time point predicted functional outcome independent of age and baseline stroke severity. Interrater agreement was better for DWI than fluid-attenuated inversion recovery (1.4 mL [8%] vs 1.8 mL [17%]; P=.002). Assessment of final infarct volume using DWI at 24 hours captures the effect of reperfusion therapies on infarct growth and predicts functional outcome similarly to imaging at day 90. This has the potential to reduce loss to follow-up in trials and may add early prognostic information in clinical practice.