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MCA Occlusion (mca + occlusion)

Distribution by Scientific Domains

Medical Sciences	100%

Distribution within Medical Sciences

Neurology	50%
Radiology & Imaging	30%

Selected Abstracts

MRI tissue characterization of experimental cerebral ischemia in rat

JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2003
Hamid Soltanian-Zadeh PhD
Abstract Purpose To extend the ISODATA image segmentation method to characterize tissue damage in stroke, by generating an MRI score for each tissue that corresponds to its histological damage. Materials and Methods After preprocessing and segmentation (using ISODATA clustering), the proposed method scores tissue regions between 1 and 100. Score 1 is assigned to normal brain matter (white or gray matter), and score 100 to cerebrospinal fluid (CSF). Lesion zones are assigned a score based on their relative levels of similarities to normal brain matter and CSF. To evaluate the method, 15 rats were imaged by a 7T MRI system at one of three time points (acute, subacute, chronic) after MCA occlusion. Then they were killed and their brains were sliced and prepared for histological studies. MRI of two or three slices of each rat brain (using two DWI (b = 400, b = 800), one PDWI, one T2WI, and one T1WI) was performed, and an MRI score between 1 and 100 was determined for each region. Segmented regions were mapped onto the histology images and scored on a scale of 1,10 by an experienced pathologist. The MRI scores were validated by comparison with histology scores. To this end, correlation coefficients between the two scores (MRI and histology) were determined. Results Experimental results showed excellent correlations between MRI and histology scores at different time points. Depending on the reference tissue (gray matter or white matter) used in the standardization, the correlation coefficients ranged from 0.73 (P < 0.0001) to 0.78 (P < 0.0001) using the entire dataset, including acute, subacute, and chronic time points. This suggests that the proposed multiparametric approach accurately identified and characterized ischemic tissue in a rat model of cerebral ischemia at different stages of stroke evolution. Conclusion The proposed approach scores tissue regions and characterizes them using unsupervised clustering and multiparametric image analysis techniques. The method can be used for a variety of applications in the field of computer-aided diagnosis and treatment, including evaluation of response to treatment. For example, volume changes for different zones of the lesion over time (e.g., tissue recovery) can be evaluated. J. Magn. Reson. Imaging 2003;17:398,409. © 2003 Wiley-Liss, Inc. [source]

Association of Pretreatment ASPECTS Scores with tPA-Induced Arterial Recanalization in Acute Middle Cerebral Artery Occlusion

JOURNAL OF NEUROIMAGING, Issue 1 2008
Georgios Tsivgoulis MD
ABSTRACT BACKGROUND AND PURPOSE The Alberta Stroke Program Early CT-Score (ASPECTS) assesses early ischemic changes within the middle cerebral artery (MCA) and predicts poor outcome and increased risk for thrombolysis-related symptomatic ICH. We evaluated the potential relationship between pretreatment ASPECTS and tPA-induced recanalization in patients with MCA occlusions. SUBJECTS & METHODS Consecutive patients with acute ischemic stroke due to MCA occlusion were treated with standard IV-tPA and assessed with transcranial Doppler (TCD) for arterial recanalization. Early recanalization was determined with previously validated Thrombolysis in Brain Ischemia (TIBI) flow-grading system at 120 minutes after tPA-bolus. All pretreatment CT-scans were prospectively scored by trained investigators blinded to TCD findings. Functional outcome at 3 months was evaluated using the modified Rankin Scale (mRS). RESULTS IV-tPA was administered in 192 patients (mean age 68 ± 14 years, median NIHSS-score 17). Patients with complete recanalization (n= 51) had higher median pretreatment ASPECTS (10, interquartile range 2) than patients with incomplete or absent recanalization (n= 141; median ASPECTS 9, interquartile range 3, P= .034 Mann-Whitney U-test). An ASPECTS ,6 was documented in 4% and 17% of patients with present and absent recanalization, respectively (P= .019). Pretreatment ASPECTS was associated with complete recanalization (OR per 1-point increase: 1.54; 95% CI 1.06,2.22, P= .023) after adjustment for baseline characteristics, risk factors, NIHSS-score, pretreatment TIBI grades and site of arterial occlusion on baseline TCD. Complete recanalization (OR: 33.97, 95% CI 5.95,185.99, P < .001) and higher ASPECTS (OR per 1-point increase: 1.91; 95% CI 1.17,3.14, P= .010) were independent predictors of good functional outcome (mRS 0,2). CONCLUSIONS Higher pretreatment ASPECT-scores are associated with a greater chance of complete recanalization and favorable long-term outcome in tPA-treated patients with acute MCA occlusion. [source]

Residual Flow Signals Predict Complete Recanalization in Stroke Patients Treated With TPA

JOURNAL OF NEUROIMAGING, Issue 1 2003
Lise A. Labiche MD
ABSTRACT Background. Residual blood flow around thrombus prior to treatment predicts success of coronary thrombolysis. The authors aimed to correlate the presence of residual flow signals in the middle cerebral artery (MCA) with completeness of recanalization after intravenous tissue plasminogen activator (TPA). Methods. The authors studied consecutive patients treated with intravenous TPA therapy who had a proximal MCA occlusion on pretreatment transcranial Doppler (TCD). Patients were continuously monitored for 2 hours after TPA bolus. Absent residual flow signals correspond to the thrombolysis in brain ischemia (TIBI) 0 grade, and the presence of residual flow signals was determined as TIBI 1-3 flow grades. Complete recanalization was defined as flow improvement to TIBI grades 4-5. Results. Seventy-five patients with a proximal MCA occlusion had median pre-bolus NIHSS 16 (85% with ,10 points). TPA bolus was given at 141 ± 56 minutes (median 120 minutes). Complete recanalization was observed in 25 (33%), partial in 23 (31%), and no early recanalization was seen in 27 (36%) patients within 2 hours after TPA bolus. Only 19% with absent residual flow signals (TIBI grade 0, n= 26) on pretreatment TCD had complete early recanalization. If pretreatment TCD showed the presence of any residual flow (TIBI 1-3, n= 49), 41% had complete recanalization within 2 hours of TPA bolus (P = .03). Conclusions. Patients with detectable residual flow signals before IV TPA bolus are twice as likely to have early complete recanalization. Those with no detectable residual flow signals have less than 20% chance for complete early recanalization with intravenous TPA and may be candidates for intra-arterial therapies. [source]

Association of growth factors with arterial recanalization and clinical outcome in patients with ischemic stroke treated with tPA

JOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 7 2010
T. SOBRINO
Summary.,Background: Growth factors (GF) such as vascular endothelial growth factor (VEGF), angiopoietin-1 (Ang-1) and granulocyte-colony stimulating factor (G-CSF) have been associated with greater efficacy of tissue plasminogen activator (tPA) in experimental studies. Objectives: To study the association of these GF with arterial recanalization and clinical outcome in patients with acute ischemic stroke treated with tPA. Methods: We prospectively studied 79 patients with ischemic stroke attributable to MCA occlusion treated with i.v. tPA within the first 3 h from onset of symptoms. Continuous transcranial color-coded sonography (TCCS) was performed during the first 2 h after tPA bolus to assess early MCA recanalization. Hemorrhagic transformation (HT) was classified according to ECASS II definitions. Good functional outcome was defined as a Rankin scale score of 0,2 at 90 days. GF levels were determined by ELISA. Results: Mean serum levels of VEGF, G-CSF and Ang-1 at baseline were significantly higher in patients with early MCA recanalization (n = 30) (all P < 0.0001). In the multivariate analysis, serum levels of VEGF (OR, 1.03), G-CSF (OR, 1.02) and Ang-1 (OR, 1.07) were independently associated with early MCA recanalization (all P < 0.0001). On the other hand, patients with parenchymal hematoma (PH) (n = 20) showed higher levels of Ang-1 (P < 0.0001). Ang-1 (OR, 1.12; P < 0.0001) was independently associated with PH, whereas patients with good outcome (n = 38) had higher levels of G-CSF (P < 0.0001). G-CSF was independently associated with good outcome (OR, 1.12; P = 0.036). Conclusions: These findings suggest that GF may enhance arterial recanalization in patients with ischemic stroke treated with t-PA, although they might increase the HT. [source]

Proton transfer ratio, lactate, and intracellular pH in acute cerebral ischemia

MAGNETIC RESONANCE IN MEDICINE, Issue 4 2007
Kimmo T. Jokivarsi
Abstract The amide proton transfer ratio (APTR) from the asymmetry of the Z -spectrum was determined in rat brain tissue during and after unilateral middle cerebral artery occlusion (MCAo). Cerebral lactate (Lac) as determined by 1H NMR spectroscopy, water diffusion, and T1, were quantified as well. Lac concentrations were used to estimate intracellular pH (pHi) in the brain during the MCA occlusion. A decrease in APTR during occlusion indicated acidification from 7.1 to 6.79 ± 0.19 (a drop by 0.3 ± 0.2 pH units), whereas pHi computed from Lac concentration was 6.3 ± 0.2 (a drop by 0.8 ± 0.2 pH units). Despite the disagreement between the two methods in terms of the size of the change in the absolute pHi during ischemia, ,APTR and pHi (and Lac concentration) displayed a strong correlation during the MCAo. Diffusion and T1, indicated cytotoxic edema following MCA occlusion; however, APTR returned slowly toward the values determined in the contralateral hemisphere post-ischemia. These data argue that the APTR during ischemia is affected not only by pHi but by other physicochemical factors as well, and indicates different aspects of pathology in the post-ischemic brain compared to those that influence water diffusion and T1,. Magn Reson Med 57:647,653, 2007. © 2007 Wiley-Liss, Inc. [source]

Neuroprotective effects of an immunosuppressant agent on diffusion/perfusion mismatch in transient focal ischemia

MAGNETIC RESONANCE IN MEDICINE, Issue 6 2004
Toshihiko Ebisu
Abstract The immunosuppressant FK506 (tacrolimus) exerts potent neuroprotection following focal ischemia in animals; however, the separate effects of FK506 on the ischemic core and penumbra have not been reported. The ischemic penumbra is clinically defined as the difference between a large abnormal area on perfusion-weighted imaging (PWI) and a smaller lesion on diffusion-weighted imaging (DWI). The goal of this study was to determine the effect of FK506 on DWI/PWI match and mismatch areas in transient focal ischemia in rats. Twelve rats were subjected to 1 hr of transient middle cerebral artery (MCA) occlusion, and given an intravenous injection of a placebo (N = 6) or 1 mg/kg FK506 (N = 6) immediately before reperfusion. Magnetic resonance imaging (MRI) was performed during MCA occlusion, and 0.5, 1, and 24 hr after reperfusion. FK506 significantly protected the ischemic brain only in the mismatch cortex where the initial apparent diffusion coefficient (ADC) was normal and there was a mild reduction of cerebral blood flow (CBF). This is the first report to describe the protective effects of FK506 on ischemic penumbra, as measured by DWI/PWI mismatch. The findings provide direct evidence for the utility of DWI/PWI mismatch as a guideline for therapeutic intervention with FK506. Magn Reson Med 51:1173,1180, 2004. © 2004 Wiley-Liss, Inc. [source]

Liposome-Encapsulated Hemoglobin Alleviates Brain Edema After Permanent Occlusion of the Middle Cerebral Artery in Rats

ARTIFICIAL ORGANS, Issue 2 2009
Akira T. Kawaguchi
Abstract Liposome-encapsulated hemoglobin (LEH) was proven to be protective in cerebral ischemia/reperfusion injury. The present study evaluated LEH in a rat model of permanent middle cerebral artery (MCA) occlusion to clarify its effect during ischemia and reperfusion. Five minutes after thread occlusion of the MCA, rats were infused with 10 mL/kg of LEH (LEH, n = 13), and compared with normal controls (n = 11). Additional animals received the same MCA occlusion with no treatment (CT, n = 11), saline (saline, n = 10), empty liposome solution (EL, n = 13), or washed red blood cells (RBC, n = 7). Severity of brain edema was determined 24 h later by signal strength in T2-weighted magnetic resonance imaging of the cortex, striatum, hippocampus, and pyriform lobe. The results showed that brain edema/infarction observed in any vehicle-infused control was significantly more severe than in LEH-treated rats. There was a tendency toward aggravated edema in rats receiving ELs. LEH infusion at a dose of 10 mL/kg significantly reduced edema formation as compared to other treatments in a wide area of the brain 24 h after permanent occlusion of the MCA. Low oncotic pressure of EL and LEH solution (vehicle solution) appeared to cause nonsignificant aggravation of edema and reduced protective effects of LEH. [source]

Combined thrombolysis with abciximab and rtPA in patients with middle cerebral artery occlusion

ACTA NEUROLOGICA SCANDINAVICA, Issue 1 2010
G. Gahn
Background,,, In patients with acute middle cerebral artery (MCA) occlusion, recanalization rates with intravenous (IV) recombinant tissue plasminogen activator (rtPA) are limited. Aim, We evaluated the feasibility and safety of combined IV thrombolysis with abciximab and reduced dose rtPA in a 3- to 6-h time window. Methods,,, We prospectively (March 2002 to February 2005) studied patients with symptomatic MCA occlusion on computed tomography (CT) angiography and absence of major early ischemic changes (EIC) on non-contrast CT (NCCT) within 3,6 h from symptom onset. Patients were treated with IV abciximab and half-standard dose rtPA. Outcome parameters were symptomatic intracerebral hemorrhage (sICH), early clinical improvement and functional independence at discharge (modified Rankin Scale score , 2). Results,,, Of 13 patients, mean age was 62 ± 11 years, onset-to-treatment time 4.8 ± 0.9 h and median baseline National Institutes of Health Stroke Scale score 11 (interquartile range 6.5,13.5). sICH occurred in one patient (8%). We observed early clinical improvement in four patients (31%). Six patients (46%) were functionally independent at discharge. Conclusions,,, In patients with acute symptomatic MCA occlusion and absence of major EIC on NCCT, combined IV thrombolysis with abciximab and half-standard dose rtPA was feasible and seemed to be safe if applied within 3,6 h from symptom onset. [source]