Quantification of image contrast of infarcts on computed tomography scans.

Introduction Accurate identification of infarcts in non-contrast computed tomography (NC-CT) scans of the brain is fundamental in the diagnosis and management of patients with stroke. Quantification of image contrast properties at the boundaries of ischemic infarct regions in NC-CT can contribute to a more precise manual or automatic delineation of these regions. Here we explore these properties quantitatively. Methods We retrospectively investigated 519 NC-CT studies of 425 patients with clinically confirmed ischemic strokes. The average and standard deviation (SD) of patients' age was 67.5 ± 12.4 years and the average(median)±SD time from symptoms onset to NC-CT examination was 27.4(12)±35.7 h. For every scan with an ischemic lesion identified by experts, the image contrast of the lesion vs. normal surrounding parenchyma was calculated as a difference of mean Hounsfield Unit (HU) of 1-5 consecutive voxels (the contrast window width) belonging to the lesion and to the parenchyma. This contrast was calculated at each single voxel of ischemic lesion boundaries (previously delineated by the experts) in horizontal and vertical directions in each image. The distributions of obtained horizontal, vertical and both contrasts combined were calculated among all 519 NC-CTs. Results The highest applicative contrast window width was identified as 5 voxels. The ischemic infarcts were found to be characterized by 6.60 HU, 8.28 HU and 7.55 HU mean values for distributions of horizontal, vertical and combined contrasts. Approximately 40-50% of the infarct boundary voxels were found to refer to the image contrast below 5 HU. Conclusion Low image contrast of ischemic lesions prevents accurate delineation of the infarcts in NC-CT.

Efficacy of cerebral thrombolysis in an extended 'time window'.

WHAT IS KNOWN AND OBJECTIVE: Cerebral systemic thrombolysis (i.v. thrombolysis) with tissue-type plasminogen activator (rt-PA) is the only proven medical therapy for ischaemic stroke. The use of i.v. thrombolysis up to 4·5 h from stroke onset was approved in certain countries in 2008, but its safety and efficacy have not been fully determined to date. OBJECTIVE: To assess the long-term outcome and complication rate of i.v. thrombolysis performed in the extended 'time window'. METHODS: The study included 403 ischaemic stroke patients consecutively treated with i.v. thrombolysis from 2006 to 2012 at three comprehensive stroke centres in Poland. The long-term outcome and the haemorrhagic complications' (HC) rate were compared between subgroups of patients treated within 3 vs. 3-4·5 h from stroke onset. RESULTS AND DISCUSSION: About 132 (32·75%) patients were treated between 3 and 4·5 h from stroke onset. Neurological deficits tended to be more severe in patients treated ≤3 than in those treated 3-4·5 h (National Institutes of Health Stroke Scale, NIHSS 12 vs.10 points; P = 0·053); however, the ratio of patients with a favourable outcome (mRS 0-2 points) and mortality did not differ between the two groups (53·9 vs. 58·3, P = 0·39 and 17·7 vs. 21·2, P = 0·39, respectively). The rate of HC also did not differ between the two groups (18·8% vs. 15·1%, P = 0·46). WHAT IS NEW AND CONCLUSION: The efficacy of i.v. thrombolysis routinely performed in an extended 'time window' is not reduced when compared to procedures performed within 3 h from symptom onset.

Intravenous rt-PA in patients with ischaemic stroke and renal dysfunction.

OBJECTIVE: Renal dysfunction (RD) increases risk for ischaemic stroke (IS). The impact of RD on the effects of iv-thrombolysis in the Caucasian population has not been fully determined. AIMS: To evaluate the associations between RD and the outcome of iv-thrombolysis in Caucasian patients with IS. METHODS: The observational, multicentre study included 404 patients with IS who were treated with iv-thrombolysis. RD was defined as estimated glomerular filtration rate ≤ 60 ml/min/1.73 m(2). Outcome was assessed with modified Rankin Score at 3 months after the stroke onset. RESULTS: Medians baseline NIHSS score did not differ between groups of patients with and without RD (12.0 vs. 11.0 pts, p=0.33). Unfavourable outcome was found in 52.1% of patients with and in 41.2% of patients without RD (p=0.05), mortality was higher in patients with RD (29.9% vs. 14.3%, p<0.001), and the presence of haemorrhagic transformation (HT) did not differ between the groups (17.1% vs. 17.1% respectively, p=0.996). A multivariate analysis showed no impact of RD on the unfavourable outcome (OR 0.98; 95%CI 0.88-1.10), mortality (OR 0.92; 95%CI 0.81-1.05) or presence of HT (OR 1.03; 95%CI 0.90-1.18). CONCLUSIONS: We found no impact of RD on the safety and efficacy of iv-thrombolysis in Caucasian patients with IS.

Automatic segmentation of ventricular cerebrospinal fluid from ischemic stroke CT images.

Accurate segmentation of ventricular cerebrospinal fluid (CSF) regions in stroke CT images is important in assessing stroke patients. Manual segmentation is subjective, time consuming and error prone. There are currently no methods dedicated to extracting ventricular CSF regions in stroke CT images. 102 ischemic stroke CT scans (slice thickness between 3 and 6 mm, voxel size in the axial plane between 0.390 and 0.498 mm) were acquired. An automated template-based algorithm is proposed to extract ventricular CSF regions which accounts for the presence of ischemic infarct regions, image noise, and variations in orientation. First, template VT(2) is registered to the scan using landmark-based piecewise linear scaling and then template VT(1) is used to further refine the registration by partial segmentation of the fourth ventricle. A region of interest (ROI) is found using the registered VT(2). Automated thresholding is then applied to the ROI and the artifacts are removed in the final phase. Sensitivity, dice similarity coefficient, volume error, conformity and sensibility of segmentation results were 0.74 ± 0.12, 0.8 ± 0.09, 0.16 ± 0.11, 0.45 ± 0.39, 0.88 ± 0.09, respectively. The processing time for a 512 × 512 × 30 CT scan takes less than 30 s on a 2.49 GHz dual core processor PC with 4 GB RAM. Experiments with clinical stroke CT scans showed that the proposed algorithm can generate acceptable results in the presence of noise, size variations and orientation differences of ventricular systems and in the presence of ischemic infarcts.

Low free triiodothyronine levels are related to poor prognosis in acute ischemic stroke.

BACKGROUND: Neuroendocrine changes are important processes which accompany critical illness, however, the number of clinical studies concentrating on the role of thyroid gland hormones in stroke pathogenesis is relatively small. The aim of this prospective study was to investigate the relation between free triiodothyronine (fT3) levels and the prognosis of patients with stroke. METHODS: The prospective study included 387 patients with acute (<24 h of symptoms onset) ischemic stroke consecutively admitted to Stroke Units. The subjects with known conditions that could interfere with thyroid gland metabolism were excluded. We analyzed: the routine blood tests, fT3, free thyroxine (fT4), thyroid-stimulating hormone (TSH) levels, unenhanced CT scans, initial clinical status (NIH Stroke Scale, NIHSS), 30- and 360- days outcome (modified Rankin Scale-mRS) and calculated the survival rate. RESULTS: A higher NIHSS score was in the 1 (st) fT3 levels tertile, whereas a lower in the 3 (rd) fT3 levels tertile (p=0.006). The 30- and 360-days mRS scores showed that patients in the lowest fT3 tertile had more severe neurological impairment than those in the highest tertile (p=0.001 and p=0.03, respectively). A 1-year mortality of the patients with the first tertile fT3 levels was significantly higher than that of the patients with the third tertile hormone levels (p=0.008). Additionally, subjects with fT3 level in the lowest tertile demonstrated higher WBC counts and the ventricular system on Computed Tomography of head performed on admission to hospital was statistically more frequent compressed than that in the patients with fT3 level in the highest tertile (p=0.02 and p=0.03, respectively). CONCLUSION: In acute stroke patients lower free T3 levels are an important factor related to unfavorable outcome, i. e., severe disability and death.

[Leukocytosis in the first day of acute ischemic stroke as a prognostic factor of disease progression]. / Leukocytoza w pierwszej dobie udaru niedokrwiennego mózgu jako czynnik prognostyczny przebiegu choroby.

It has been reported that white blood cells (WBC) may contribute to the initiation and further development of stroke. WBC count could have influence on hemorheology, thrombosis and induction of vasoconstriction in cerebral arteries. The aim of this work was to determine whether WBC count assessed in patients with acute stroke in the first day of the disease have a predictive value for the late clinical outcomes. Peripheral WBC count was measured at the admission to the hospital in 100 consecutive patients with acute stroke. Ischemic stroke was confirmed in all patients by head CT. Neurological status was evaluated with the use of modified Rankin's Scale. We assessed the following clinical outcomes: in-hospital mortality, the lack of neurological improvement on the 21st day of disease, and the need for hospital stay longer than 21 days. Odds ratio (OR) with 95% confidence interval (95% CI) adjusted for patient's age, gender, cardiovascular diseases, diabetes mellitus and previous stroke was calculated with the use of logistic regression. OR was evaluated both for the presence of WBC count > 10.000 cells/microliter and for each 1000 leukocytes/microliter increase. WBC count greater than 10.000 cells/microliter was associated with a more than seventy-fold greater risk for death (OR--75.18; 95% CI: 8.89-635.84; p = 0.0001), nearly eight times increased risk for the no-improvement status (OR--7.78; 95% CI: 2.51-24.17; p = 0.0004) and approximately four times increased risk for the prolonged hospital stay (OR--4.20; 95% CI: 1.50-11.72; p = 0.0062). Each 1000 cell/microliter increase in WBC count at the admission was associated with increased risk for in-hospital mortality (OR--2.24; 95% CI: 1.39-3.57; p = 0.0008), no neurological improvement (OR--1.43; 95% CI: 1.15-1.76; p = 0.0009) and the need for prolonged hospitalization (OR--1.26; 95% CI: 1.07-1.49; p = 0.0066). Increased WBC count within the first 12 hours of stroke is an independent and strong risk factor for mortality, no neurological improvement, and the need for prolonged hospitalization in the course of acute ischemic stroke.

[Intima-media complex thickness of common carotid artery as a risk factor for stroke]. / Grubosc kompleksu intima-media tetnic szyjnych wspólnych oceniona metoda ultrasonografii jako czynnik ryzyka udaru niedokrwiennego mózgu.

Intima-Media Thickness (IMT) of Common Carotid Artery (CCA) could be seen as the atherosclerotic risk factors' final morphological effect. We investigated the hypothesis that IMT of CCA is significantly different in sex- and age-matched groups of persons with stroke and healthy subjects. 47 patients with first-ever atherothrombotic stroke proven by CT were investigated. Patients with atrial fibrillation, valvular heart disease and left ventricular hyperthrophy were excluded. The IMT of CCA were estimated by High-Resolution B-Mode Ultrasonography. All the patients had bilateral IMT measurement within 20 mm proximal to the carotid bulb on the far wall in the anterioposterior and laterolateral plane. The results were compared with those obtained in 50 healthy sex- and age-matched subjects. We found a strong association between IMT and stroke (p < 0.0001). Mean IMT was 0.96 mm (SD 0.18) in patients and 0.70 mm (SD 0.09) in controls. The presence of atherosclerotic plaques was 0.34 and 0.08 for patients and controls respectively (p = 0.0025). IMT of CCA is strongly positively associated with the risk for stroke. The frequency of atherosclerotic plaques in CCAs is statistically significantly higher in stroke patients than in control group.

[Infection as a likely risk factor for ischemic stroke]. / Zakazenia jako prawdopodobny czynnik ryzyka udaru niedokrwiennego mózgu.

This review presents recent informations concerning the role of viral and bacterial (especially Helicobacter pylori and Chlamydia pneumoniae) infections in the development of ischaemic stroke. Among possible pathogenic pathways that link infections and stroke, the special attention is paid to the coagulation abnormalities and immunological reactions.