| 21. |
- Merlo, Juan, et al.
(author)
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Diastolic blood pressure and area of residence: multilevel versus ecological analysis of social inequity
- 2001
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In: Journal of Epidemiology and Community Health. - : BMJ. - 1470-2738 .- 0143-005X. ; 55:11, s. 791-798
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Journal article (peer-reviewed)abstract
- STUDY OBJECTIVES---To study geographical differences in diastolic blood pressure and the influence of the social environment (census percentage of people with low educational achievement) on individual diastolic blood pressure level, after controlling for individual age and educational achievement. To compare the results of multilevel and ecological analyses. DESIGN---Cross sectional analysis performed by multilevel linear regression modelling, with women at the first level and urban areas at the second level, and by single level ecological regression using areas as the unit of analysis. SETTING---Malmö, Sweden (population 250 000). PARTICIPANTS---15 569 women aged 45 to 73, residing in 17 urban areas, who took part in the Malmö Diet and Cancer Study (1991-1996). MAIN RESULTS---In the "fixed effects" multilevel analysis, low educational achievement at both individual (beta =1.093, SE=0.167) and area levels (beta =2.966, SE=1.250) were independently associated with blood pressure, although in the "random effects" multilevel analysis almost none of the total variability in blood pressure across persons was attributable to areas (intraclass correlation=0.3%). The ecological analysis also found an association between the area educational variable and mean diastolic blood pressure (beta =4.058, SE=1.345). CONCLUSIONS---The small intraclass correlation found indicated very marginal geographical differences and almost no influence of the urban area on individual blood pressure. However, these slight differences were enough to detect an effect of the social environment on blood pressure. The ecological study overestimated the associations found in the "fixed" effects multilevel analysis, and neither distinguished individual from area levels nor provided information on the intraclass correlation. Ecological analyses are inadequate to evaluate geographical differences in health.
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| 22. |
- Nilsson, Ola, et al.
(author)
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Prediction of death in patients with primary intracerebral hemorrhage: a prospective study of a defined population.
- 2002
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In: Journal of Neurosurgery. - 0022-3085. ; 97:3, s. 531-536
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Journal article (peer-reviewed)abstract
- OBJECT: Predictors of early (30-day) and long-term (1-year) mortality rates after primary intracerebral hemorrhage (ICH) were studied in a large population in southern Sweden. METHODS: All cases of primary ICH, verified using computerized tomography (CT) scanning or autopsy study, were prospectively registered at the 12 hospitals covering a defined population of 1.14 million during the calendar year 1996. Mortality was analyzed in relation to CT findings (hematoma location and volume and ventricular extension) and clinical parameters (patient age and sex, level of consciousness on admission, and history of preictal risk factors) by using univariate and multivariate statistical methods. Three hundred forty-one cases of primary ICH were detected. The overall mortality rate was 36% at the 30-day and 47% at the 1-year follow up. Multivariate analysis revealed that initial level of consciousness, hematoma volume, and a history of heart disease were independent predictors of death at 30 days postictus. One year after bleeding, independent predictors of mortality were the initial level of consciousness, patient age, and hematoma location. CONCLUSIONS: Primary ICH remains a stroke subtype associated with a high mortality rate and for which the level of consciousness on admission is the strongest predictor of fatal outcome both at 30 days and during the 1st year after bleeding. A preictal history of heart disease increased the 30-day mortality rate.
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| 23. |
- Sjöblom, Lars, et al.
(author)
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Management and prognostic features of intracerebral hemorrhage during anticoagulant therapy - A Swedisih multicenter study
- 2001
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In: Stroke: a journal of cerebral circulation. - : Ovid Technologies (Wolters Kluwer Health). - 1524-4628 .- 0039-2499. ; 32:11, s. 2567-2574
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Journal article (peer-reviewed)abstract
- Background and Purpose-Patients treated with oral anticoagulants (ACs) have an increased risk of intracerebral hemorrhage (ICH), which is more often fatal than spontaneous ICH. Options to reverse the AC effect include intravenous administration of vitamin K, plasma, and coagulation factor concentrate. However, the optimal management of AC-related ICH has not been determined in any randomized trial. In this study, the present management of AC-related ICH was surveyed, and determinants of survival were assessed. Methods-We retrospectively reviewed the medical records of all AC-related ICHs at 10 Swedish hospitals during a 4-year period, 1993 to 1996. Survival status after the ICH was determined from the Swedish National population register. Results-We identified 151 patients with AC-related ICH. Death rates were 53.6% at 30 days, 63.6% at 6 months, and 77.5% at follow-up (mean 3.5 years). The case fatality ratio at 30 days was 96% among patients unconscious on admission (n=27), 80% among patients who became unconscious before active treatment was started (n=15), 55% among patients in whom no special action was taken except withdrawal of AC treatment (n=42), and 28% among patients given active anti-coumarin treatment while they were still conscious (n=64). The case fatality, ratio at 30 days was 11% in the group treated with plasma (n = 18), 30% in the group treated with vitamin K (n = 23), and 39% in the group treated with coagulation factor concentrate (n=23). Within the first 24 to 48 hours after admission, 47% of the patients deteriorated. Choice of therapy to reverse the AC effect differed substantially between the hospitals (P <0.0001), as did the time interval from symptom onset to start of treatment. Multiple logistic regression analysis showed only 2 factors (intraventricular extension of bleeding and ICH volume) that were independently related to case fatality at both 30 days and 6 months. The results were similar when the analysis was restricted to patients who were conscious on admission. Conclusions-In AC-related ICH, a progressive, neurological deterioration during the first 24 to 48 hours after admission is frequent, and the mortality is high. Choice of therapy to reverse the AC effect differed considerably between the hospitals. There was no evidence that any treatment strategy was superior to the others. A randomized controlled trial is needed to determine the best choice of treatment.
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| 24. |
- Staaf, Gert, et al.
(author)
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Diffusion-weighted MRI findings in patients with capsular warning syndrome
- 2004
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In: Cerebrovascular Diseases. - : S. Karger AG. - 1421-9786 .- 1015-9770. ; 17:1, s. 1-8
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Journal article (peer-reviewed)abstract
- Background and Purpose: The 'capsular warning syndrome' (CWS) of recurrent stereotyped episodes of motor or sensory dysfunction is clinically well recognized, and is associated with a high risk of imminent lacunar infarction with permanent deficits resembling those of CWS. However, the pathophysiology of CWS has not been well characterized. We report a clinicoanatomic correlation with MR imaging studies in the acute and chronic phases in patients with CWS. Material and Methods: Between April 1997 and March 2001, we prospectively studied 8 patients, mean age 73.3 years, presenting with 4 - 17 motor or sensorimotor transient ischemic attacks ( TIAs; duration 2 - 90 min) up to 3 days after onset of the first episode. Four patients were free of symptoms between the attacks and had no residua, whereas 4 patients developed a pure motor or sensorimotor stroke within 1 - 3 days after symptom onset. Diffusion-weighted echoplanar MRI (DWI) and T-2-weighted MRI studies were performed within 1 week after symptom onset and were repeated 1 - 2 months later. Results: Seven of the 8 patients had an appropriate lesion on DWI in the acute phase. DWI abnormalities in the 3 patients with TIAs were 4 - 10 mm in diameter and confined to the lateral thalamus or medial globus pallidus without involving the internal capsule, whereas 4 patients who developed a stroke had abnormalities localized to the putamen extending to corona radiata ( 3 patients), or the pontomesencephalic junction ( 1 patient). All 6 patients who underwent follow-up MRI had an infarct on T-2-weighted images corresponding to, but usually smaller than, the acute phase DWI abnormality. Conclusions: Small infarcts in the basal ganglia or the pons, close to central motor pathways, appear to be the primary lesion in CWS. The pathophysiology of CWS is complex, and may involve hemodynamic mechanisms in penetrating arterial territories, as well as molecular mechanisms, such as peri-infarct depolarizations affecting adjacent motor pathways. Copyright (C) 2004 S. Karger AG, Basel.
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| 25. |
- Staaf, Gert, et al.
(author)
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Pure motor stroke from presumed lacunar infarct - Long-term prognosis for survival and risk of recurrent stroke
- 2001
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In: Stroke: a journal of cerebral circulation. - : Ovid Technologies (Wolters Kluwer Health). - 1524-4628. ; 32:11, s. 2592-2596
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Journal article (peer-reviewed)abstract
- Background and Purpose-A low risk of recurrent stroke and death after lacunar infarction has previously been reported, but follow-up has been limited to less than or equal to5 years. Methods-One hundred eighty patients with pure motor stroke, collected between 1983 and 1986 from a hospital-based stroke registry, were followed up until at least 10 years after the index stroke. Two patients were lost to follow-up. Survival status was determined from the official population registry and compared with survival rates of the Swedish population, matched for age and sex. Cox proportional hazards regression analyses were used to identify independent prognostic predictors. Results-During follow-up 106 (60%) of the 178 patients died, most commonly as a result of coronary heart disease. During the first 5 years after the stroke, survival rates were similar to those of the general population. Beyond this time the risk of death was increased among patients with pure motor stroke, with an excess of 10 to 15 percent units compared with the general population. Independent determinants for death were age (P <0.01), male sex (P <0.01), and nonuse of acetylsalicylic acid (P=0.02). Recurrent stroke occurred in 42 (23.5%) of the patients, corresponding to an annual risk of 2.4%. Hypertension (P=0.025) and diabetes (P=0.024) were independent risk factors for recurrent stroke. Conclusions-For the first few years after lacunar infarct, the risk of death was similar to that of the general population, but later a clear excess of death was observed. The long-term prognosis in lacunar infarction appears less favorable than previously reported.
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| 26. |
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| 27. |
- Sundgren, PC, et al.
(author)
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Carotid artery stenosis: contrast-enhanced MR angiography with two different scan times compared with digital subtraction angiography
- 2002
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In: Neuroradiology. - : Springer Science and Business Media LLC. - 1432-1920 .- 0028-3940. ; 44:7, s. 592-599
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Journal article (peer-reviewed)abstract
- Contrast enhanced magnetic resonance angiography (CE MRA) is a non-invasive alternative to conventional digital subtraction angiography (DSA). CE MRA is increasingly used as a complement to Duplex in the preoperative assessment of carotid artery stenosis. The purpose of this study was to determine if CE MRA could replace preoperative DSA. CE MRA with a scan time of 10 or 28 s was performed in 24 consecutive patients who were scheduled for preoperative DSA because of Duplex-verified severe carotid artery stenosis. Two neuroradiologists measured the degree of stenosis with three different methods, and the image quality was evaluated. DSA was used as the gold standard. For detection of severe stenosis (N. American symptomatic carotid endarterectomy trial (NASCET) greater than or equal to70%; European symptomatic carotid endarterectomy trial (ECST) greater than or equal to80%; common carotid artery method (CCAM) greater than or equal to80%), the sensitivity of CE MRA maximum intensity projection (MIP) compared with DSA was 82%-100%, the specificity was 74%-93% and the accuracy was 77%-90%. The inter-observer agreement was higher, the image quality was better and the intracranial main arteries were better visualized with the 28 s than with the 10 s scan time. The enhancement of the jugular veins seen in 17% of the 10 s scans and in 58% of the patients with the 28 s scans did not interfere with the evaluation of the carotid arteries. CE MRA, preferably with a scan time of 28 s, can replace DSA in the preoperative assessment of most patients with carotid artery stenosis.
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| 28. |
- Wirestam, Ronnie, et al.
(author)
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Absolute cerebral blood flow measured by dynamic susceptibility contrast MRI: a direct comparison with Xe-133 SPECT
- 2000
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In: Magma. - 1352-8661. ; 11:3, s. 96-103
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Journal article (peer-reviewed)abstract
- Absolute regional cerebral blood flow (CBF) was measured in ten healthy volunteers, using both dynamic susceptibility-contrast (DSC) magnetic resonance imaging (MRI) and Xe-133 SPECT within 4 h. After i.v. injection of Gd-DTPA-BMA (0.3 mmol/kg b.w.), the bolus was monitored with a Simultaneous Dual FLASH pulse sequence (1.5 s/image), providing one slice through brain tissue and a second slice through the carotid artery. Concentration C(t) is proportional to -(1/TE) ln[S(t)/S(0)] was related to CBF as C(t) = CBF [AIF(t) x R(t)], where AIF is the arterial input function and R(t) is the residue function. A singular-value-decomposition-based deconvolution technique was used for retrieval of R(t). Absolute CBF was given by Zierler's area-to-height relation and the central volume principle. For elimination of large vessels (ELV), all MRI-based CBF values exceeding 2.5 times the mean CBF value of the slice were excluded. A correction for partial-volume effects (CPVE) in the artery used for AIF monitoring was based on registration of signal in a phantom with tubes of various diameters (1.5-6.5 mm), providing an individual concentration correction factor applied to AIF data registered in vivo. In the Xe-133 SPECT investigation, 3,000-4,000 MBq of Xe-133 was administered intravenously, and CBF was calculated using the Kanno Lassen algorithm. When ELV and CPVE were applied, DSC-MRI showed average CBF values from the entire slice of 43 +/- 10 ml/(min 100 g) (small-artery AIF) and 48 +/- 17 ml/(min 100 g) (carotid-artery AIF) (mean +/- S.D., n = 10). The corresponding Xe-133-SPECT-based CBF was 33 +/- 6 ml/(min 100 g) (n = 10). The relationships of CBF(MRI) versus CBF(SPECT) showed good linear correlation (r = 0.74-0.83).
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| 29. |
- Wirestam, Ronnie, et al.
(author)
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Assessment of regional cerebral blood flow by dynamic susceptibility contrast MRI using different deconvolution techniques
- 2000
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In: Magnetic Resonance in Medicine. - 1522-2594. ; 43:5, s. 691-700
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Journal article (peer-reviewed)abstract
- Regional cerebral blood flow (rCBF) was assessed using dynamic susceptibility-contrast MRI at 1.5 T. A simultaneous dual FLASH pulse sequence and Gd-DTPA-BMA (0.3 mmol/kg b.w.) were used for examination of 43 volunteers, measuring rCBF in frontal white matter (WM) and in gray matter in the thalamus (GM). Arterial input functions (AIFs) were registered 1) in the carotid artery and 2) in an artery within the GM/WM slice. The measured concentration-vs. -time curve was deconvolved with the AIF using both Fourier Transform (FT) and Singular Value Decomposition (SVD). Relative rCBF was given by the height of the deconvolved response curve. For each volunteer, eight different rCBF maps were calculated, representing different combinations of deconvolution techniques, AIFs, and filters. The average GM-WM rCBF ratios ranged from 2.0-2.2, depending on methodology. Absolute rCBF was 68 +/- 28 ml/(min 100 g) in GM and 35 +/- 13 ml/(min 100g) in WM (mean +/- SD, n = 39). GM-WM rCBF ratios obtained using SVD were 6-10% higher than corresponding ratios obtained using FT.
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| 30. |
- Wirestam, Ronnie, et al.
(author)
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Perfusion-related parameters in intravoxel incoherent motion MR imaging compared with CBV and CBF measured by dynamic susceptibility-contrast MR technique
- 2001
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In: Acta Radiologica. - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 42:2, s. 123-128
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Journal article (peer-reviewed)abstract
- OBJECTIVE: Perfusion-related parameters obtained by intravoxel incoherent motion (IVIM) MR imaging (MRI) were compared with cerebral blood volume and flow (CBV and CBF), retrieved by dynamic susceptibility-contrast (DSC) MRI. MATERIAL AND METHODS: Twenty-eight volunteers (average age 68.5 years) were investigated. Spin-echo echo-planar imaging with IVIM-encoding gradients was employed (36 different b values, 0-1200 s/mm2). The perfusion fraction and the pseudo-diffusion coefficient were calculated for regions in thalamus gray matter and frontal white matter, using asymptotic and full fitting. In DSC-MRI, a Gd-DTPA-BMA contrast-agent bolus was monitored using simultaneous-dual FLASH. Deconvolution of the measured tissue concentration-versus-time curve with an arterial input function from the carotid artery was applied, and maps of CBV and CBF were calculated. RESULTS: The correlation between the perfusion fraction and CBV was r=0.56 (p<0.0000006) using asymptotic fitting, and r=0.35 (p<0.0004) when full fitting was applied. Average CBF was 41.5 ml/(min 100 g), to be compared with the IVIM-based value of 63.6 ml/(min 100 g), obtained from the median value of the pseudo-diffusion coefficient in combination with assumptions about capillary network structure. CONCLUSION: The IVIM concept provided results that agreed reasonably with conventional CBV and CBF. The non-linear fitting to noisy signal data was problematic, in accordance with previously presented simulations.
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