Peiyi Gao

Contrast Extravasation on Computed Tomography Angiography Predicts Clinical Outcome in Primary Intracerebral Hemorrhage: A Prospective Study of 139 Cases

Background and Purpose— Several retrospective studies suggested that contrast extravasation on CT angiography predicts hematoma expansion, poor outcome, and mortality in primary intracerebral hemorrhage. We aimed to determine the predictive value of contrast extravasation on multidetector CT angiography for clinical outcome in a prospective study. Methods— In 160 consecutive patients with spontaneous intracerebral hemorrhage admitted within 6 hours of symptom onset, noncontrast CT and multidetector CT angiography were performed on admission. A follow-up noncontrast CT was done at 24 hours. Multidetector CT angiography images were analyzed to identify the presence of contrast extravasation. Clinical outcome was assessed by modified Rankin Scale on discharge and at 90 days. Results— A total of 139 patients with primary intracerebral hemorrhage were included in the final analysis. Contrast extravasation occurred in 30 (21.6%) patients. The presence of contrast extravasation was associated with increased hematoma expansion (P<0.0001), in-hospital mortality (P=0.008), prolonged hospital stay (P=0.006), poor outcome on discharge (P=0.025), increased 3-month mortality (P=0.009), and poor clinical outcome (P<0.0001). In multivariate analysis, contrast extravasation was a promising independent predictor (OR, 10.5; 95% CI, 3.2–34.7; P<0.0001) for 90-day poor clinical outcome followed by the presence of intraventricular hemorrhage (OR, 3.4; 95% CI, 1.5–7.7; P=0.003) and initial hematoma volume (OR, 1.0; 95% CI, 1.0–1.1; P=0.013). Conclusions— The presence of contrast extravasation on multidetector CT angiography in patients with hyperacute-stage intracerebral hemorrhage is an independent and strong factor associated with poor outcome. Any patient with intracerebral hemorrhage with such sign on multidetector CT angiography should be monitored intensely and treated accordingly.

Three-tesla magnetic resonance imaging study of cerebral microbleeds in patients with ischemic stroke.

Abstract Objectives: The aims of this study were to analyse the distribution of cerebral microbleeds (CMBs) in patients with ischemic stroke and study the relationship between CMBs and the severity of old lacunar infarcts and cerebral white matter changes. Methods: The study population consisted of 247 consecutive inpatients with ischemic stroke. Magnetic resonance imaging findings of these inpatients were observed. CMBs were counted respectively according to their locations, including the corticosubcortical regions, basal ganglia, thalami, brainstem and cerebellum. The number of the old lacunes and the severity of the cerebral white matter changes were also recorded. Based on the occurrence of CMBs, the patients were divided into two groups (72 patients with CMBs; 175 patients without CMBs). Results: The most common location of CMBs in patients with ischemic stroke was the basal ganglia, followed by the corticosubcortical region, the thalami, the brainstem and the cerebellum. The severity of CMBs was closely correlated with the severity of lacunar infarcts and cerebral white matter changes, respectively. Discussion: CMBs are closely related with cerebral microangiopathy and may be a marker of advanced stage cerebral microangiopathy.

Effect of baseline magnetic resonance imaging (MRI) apparent diffusion coefficient lesion volume on functional outcome in ischemic stroke

Abstract Objective: We explored the relationship between predicted infarct core, predicted ischemic penumbras and predicted final infarct volumes obtained though apparent diffusion coefficient (ADC)-based method, as well as other clinical variables, and functional outcome. Methods: Patients with acute cerebral ischemic stroke were retrospectively recruited. The National Institutes of Health Stroke Scale score was evaluated at baseline and the modified Rankin Scale (mRS) at day 90. Favorable outcome was defined as an mRS score of 0 to 2, and unfavorable outcome as 3 to 6. Multimodal stroke magnetic resonance imaging was carried out at presentation. The volumes of diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) were measured using the regions of interest (ROI) method. The volumes of predicted infarct core, predicted ischemic penumbra and predicted final infarct were obtained by an automated image analysis system based on baseline ADC maps. The association between baseline magnetic resonance imaging volumes, baseline clinical variables, and functional outcome was statistically analyzed. Results: The study included 30 males and 20 females (mean±SD age, 56±10 years). Baseline DWI, PWI and PWI-DWI mismatch volumes were not correlated with day-90 mRS (P>0·05). Predicted infarct core, predicted ischemic penumbra and predicted final infarct through ADC-based method were all correlated with day-90 mRS (P<0·05). A better outcome was associated with a smaller predicted volume. Low baseline National Institutes of Health Stroke Scale and recanalization also demonstrated a trend toward a favorable outcome. Receiver operating characteristic analysis showed that the area under the curve of predicted final infarct volume and recanalization were higher with statistical significance (P<0·001). Discussion: Predicted volumes obtained from ADC-based methods, especially predicted final infarct volume, as well as baseline National Institutes of Health Stroke Scale and recanalization may have effect on functional outcome in acute ischemic stroke.

Association between cerebral microbleeds and the first onset of intracerebral hemorrhage - a 3.0 T MR study.

Background Cerebral microbleeds (CMBs) detected by gradient-echo MRI have been proven to be a potential risk factor for further bleeding, while the association between CMBs and the first onset of intracerebral hemorrhage has not been well investigated. Purpose To analyze the association between CMBs and the first onset of primary intracerebral hemorrhage (pICH). Material and Methods Two hundred and two consecutive inpatients with ICH and 234 consecutive outpatients without ICH as control group were enrolled in this study. MR imaging including T2*-GRE, T1W, T2W and fluid attenuated inversion recovery (FLAIR) sequences were performed to detect CMBs and other abnormalities. Prevalence, distribution, and grades of CMBs, as well as the location and size of the intracerebral hematoma were analyzed, respectively. Comparison was made between pICH and control group. Logistic analysis was performed to evaluate the association between CMBs and ICH. The correlation between hematoma size and CMBs grade/numbers was analyzed. Results CMBs were detected in 140 patients in pICH (69.3%) group and 62 patients in control group (26.5%). The incidence of CMBs in pICH group was significantly higher than that in control group (P < 0.0001). As the logistic regression analysis results, CMBs was the risk factor associated with ICH, with modulation OR value of 8.363 (95% CI 5.210–13.421). The volume of ICH with CMBs was 12.57 ± 17.23 mL, and the volume of ICH without CMBs was 17.77 ± 26.97 mL. Negative correlation was demonstrated between CMBs number and ICH volume (rs = −0.1769, P = 0.0118), as well as between CMBs grade and hematoma volume (rs = −0.1185, P = 0.1557). Conclusion CMBs may be an independent risk factor for the first onset of intracerebral hemorrhage.

Can baseline magnetic resonance angiography (MRA) status become a foremost factor in selecting optimal acute stroke patients for recombinant tissue plasminogen activator (rt-PA) thrombolysis beyond 3 hours?

Abstract Objective: We investigated whether baseline vessel status evaluated by magnetic resonance angiography (MRA) can be the foremost factor to classify acute ischemic stroke patients into subgroups for thrombolytic therapy within 3–6 hours of symptom onset. Methods: Acute ischemic stroke patients beyond 3 hours after symptom onset were examined by stroke magnetic resonance imaging (MRI) (diffusion- and perfusion-weighted imaging, and MRA) before and after thrombolysis treatment within 24–48 hours. Stroke MRI was used to classify acute ischemic stroke patients into subgroups and select optimal patients for thrombolytic treatment. Clinical scores were compared to determine whether there were significant differences among subgroups. Results: The difference in day 90 modified Rankin scale (mRS) between treated salvageable and untreated salvageable patients with recombinant tissue plasminogen activator (rt-PA) was remarkably statistically significant (p=0.02). Treated salvageable patients had more favorable clinical outcomes as compared with the untreated salvageable patients. Patients who did not have baseline artery occlusion were associated with more favorable clinical outcomes than untreated salvageable patients (p<0.001). The difference between treated salvageable and patients without artery occlusion in 90 day mRS score was not statistically significant (p=0.058). Conclusion: Baseline vessel status evaluated by MRA may be used as the first factor ahead of mismatch to categorize acute ischemic stroke patients into subgroups. Patients who do not have initial vessel occlusion may not need thrombolytic therapy.

Imaging-based thrombolysis trial in acute ischemic stroke-II (ITAIS-II)

BACKGROUND Intravenous (i.v.) recombinant tissue plasminogen activator (rtPA) remains the only approved therapy for acute ischemic stroke. However, the use of i.v. thrombolysis is restricted to a minority of patients by the rigid 3-h time window. Modern imaging-based selection algorithms that can identify penumbra have been proposed as methods to extend the window and to select patients more likely to respond favorably or unfavorably to i.v. thrombolysis. AIMS We aim to compare the safety and efficacy of multiparametric computed tomography (CT)-based i.v. thrombolysis after 3-9 h of symptom onset with standard CT-based thrombolysis within 3 h and with CT-based thrombolysis or placebo after 3-6 h from the pooled data of the large stroke rtPA trials. DESIGN The imaging-based thrombolysis trial in acute ischemic stroke-II study is a prospective, multicenter and assessor-blind controlled study. The primary efficacy outcome will be a favorable outcome at 90 days defined as a modified Rankin Scale and reperfusion improvement 24-36 h after treatment; the primary safety end-point outcome will be intracerebral hemorrhage 24-36 h after treatment. We aim to include 200 patients by 2010. It is registered with IRCTN number: ISRCTN12033002.

Brain Magnetic Resonance Elastography on Healthy Volunteers: A Safety Study

Background: Magnetic resonance elastography (MRE) is a recently developed imaging technique that can directly visualize and quantitatively measure tissue elasticity. Purpose: To evaluate the safety of brain MRE on human subjects. Material and Methods: The study included 20 healthy volunteers. MRE sequence scan (drive signal not applied to external force actuator) and MRE study were separately performed on each volunteer at an interval of more than 24 hours. The heart rate and blood pressure of each volunteer were measured immediately before and after MRE sequence scan and MRE study. Electroencephalography (EEG) was also performed within 2 hours after each scan. The volunteers were asked about their experience of the two scans. Randomized-block analysis of variance (ANOVA) was used to analyze the data of blood pressure and heart rate. Paired t test was used to analyze the data of the two EEG examinations. The volunteers were followed up 1 week after the examination. Results: All procedures were performed on each volunteer, and no one complained of obvious discomfort. No related adverse events were reported during follow-up. There was no statistically significant difference in heart rate or blood pressure. There was a statistically significant difference (P<0.05) in EEG results in the right temporoparietal region. Increased power was found in the theta, delta, alpha, and beta2 bands. No brain injury was detected by the EEG examinations. Conclusion: Based on the study results, brain MRE examinations are safe to perform on human subjects.

Hemodynamic parameters distribution of upstream, stenosis center, and downstream sides of plaques in carotid artery with different stenosis: a MRI and CFD study

Background Histopathological studies have shown significant differences in plaque components and surface conditions between upstream and downstream of the stenosis. It can be deduced that the flow status near the plaques is different from the flow status at the upstream side, stenosis center, or downstream side of the plaque. Purpose To study the hemodynamic parameter distribution in different locations near atherosclerotic plaques in the carotid arteries with different stenosis degrees. Material and Methods Eleven patients were recruited in this study. CE-MRA was performed to obtain the carotid three-dimensional surface data and the stenosis degrees were calculated. The hemodynamic parameters including wall shear stress (WSS), pressure, and velocity near the plaques were obtained by computational fluid dynamic (CFD) method. Local hemodynamics parameters were analyzed and compared between different stenosis degree groups, and between upstream, stenosis center, and downstream sides of plaques. Relative ratio of velocity, WSS, and pressure values in different locations was calculated and compared. Results Fourteen carotid arteries (with 4 mild, 6 moderate, and 4 severe stenosis) were analyzed. Significant differences were found in Pressure max (P = 0.025), Pressure mean (P = 0.020), and Pressure min (P = 0.026) between three stenosis groups. It showed significant differences in Vmin (P < 0.001) and WSSmin (P < 0.001) between three different locations. It showed upstream to downstream ratio of WSSmax (P = 0.034) and WSSmean value (P = 0.042) was significantly different between mild and moderate/severe groups. Significant differences were found in upstream to stenosis center ratio of Pressure max value (P = 0.018), Pressure mean value (P = 0.029), and Pressure min value (P = 0.026), as well as in stenosis center to downstream ratio of Pressure min value (P = 0.042). Conclusion Velocity, WSS, pressure, and relative ratio of these parameters have certain trends in distribution around the plaques in the carotid arteries.

Prediction of Infarct Core and Salvageable Ischemic Tissue Volumes by Analyzing Apparent Diffusion Coefficient Without Intravenous Contrast Material

RATIONALE AND OBJECTIVES To investigate whether baseline apparent diffusion coefficient (ADC) maps can be employed to predict both infarct core and salvageable ischemic tissue volumes in acute ischemic stroke. MATERIALS AND METHODS An automated image analysis system based on baseline ADC maps was tested against 30 patients with acute ischemic stroke of anterior circulation to predict both infarct core and salvageable ischemic tissue volumes. The predicted infarct core and predicted salvageable ischemic tissue were quantitatively and qualitatively compared with follow-up imaging data in recanalization and no recanalization groups, respectively. Direct comparisons with perfusion- and diffusion- weighted magnetic resonance imaging measures were also made. Wilcoxon signed-rank test, Spearman rank correlation, and Bland-Altman plots were performed. RESULTS In the recanalization group, the predicted infarct core volume was significantly correlated with the final infarct volume (r = 0. 868, P < .001). In the no recanalization group, the predicted final infarct volume (sum of the predicted infarct core and salvageable ischemic tissue volumes), as well as the predicted salvageable ischemic tissue volume, was also significantly correlated with the true final infarct volume (r = 0.955, P < .001) and infarct growth (r = 0.918, P < .001), respectively. The volumes of perfusion-diffusion mismatch were significantly larger than those of infarct growth and predicted salvageable ischemic tissue. Good agreement between predicted and true final infarct lesions was visualized by Bland-Altman plots in two groups. Direct visual comparative analysis revealed good qualitative agreement between the true final infarct and predicted lesions in 21 patients. CONCLUSION The proposed ADC based approach may be a feasible and practical tool to predict the volumes of infarct core and salvageable ischemic tissue without intravenous contrast media-enhanced perfusion-weighted imaging at baseline.

Ischemic lesion typing on computed tomography perfusion and computed tomography angiography in hyperacute ischemic stroke: a preliminary study

Abstract The ability to rapidly and accurately evaluate the location and extent of hyperacute brain ischemia is of major clinical importance. Herein, we aimed to develop imaging criteria to classify the ischemic lesion by computed tomography (CT) perfusion (CTP) and CT angiography (CTA) in hyperacute ischemic stroke patient. Non-contrast-enhanced CT, CTP and CTA were performed in patients with symptoms of hyperacute stroke lasting <8 hours. According to the volume of infarct core, ischemic penumbra and vessel status, three ischemic lesion types were defined. Twenty-six patients were included in our study. Among them, ten patients were classified into severe group, 15 patients were classified into mild group and one patient was classified into reversible group. In acute stroke patients, the ischemic lesion typing may assist in individualizing therapeutic decisions for patients by possibly extending the window for giving thrombolytics beyond the current 3 hour limit.