Biomedical subjects

Thomas Kucinski

Publications and source records attributed to Thomas Kucinski.

At least 19 recordsLinked to original sources

PubMed2006

Blood-oxygen-level-dependent MRI allows metabolic description of tissue at risk in acute stroke patients.

BACKGROUND AND PURPOSE: The delineation of the "penumbra" is of particular interest in acute stroke imaging. The "mismatch concept" applying perfusion-weighted imaging (PWI) and diffusion-weighted imaging (DWI) appears to be an oversimplification of the underlying electrophysiological tissue status. An additional parameter reflecting the metabolic state of the threatened brain tissue would improve our ability to describe the penumbra. One candidate is deoxyhemoglobin (deoxy-Hb) as an indicator of the oxygen extraction fraction that can be visualized by T2*-based blood oxygen level-dependent (BOLD) imaging. METHODS: We analyzed data from 32 patients with acute stroke in the territory of the middle cerebral artery. MRI included fluid-attenuated inversion recovery, DWI, PWI, time-of-flight angiography, and quantitative T2 and T2* (qT2, qT2*) imaging. Follow-up was performed on day 1 and days 5 to 8. We calculated 1/T2'=1/qT2*-1/qT2. Changes of T2', representing the deoxy-Hb effect, were analyzed by 3D regions of interest (ROIs): apparent diffusion coefficient lesion day 0 (L0), time-to-peak-lesion day 0 (T0), final infarct size days 5 to 8 (F5-8), lesion growth (LG; F5-8-L0), and surviving tissue (ST; T0-F5-8). RESULTS: We observed a clear decrease of T2' in the infarcted hemisphere compared with the unaffected control ROIs. The mean value showed the most pronounced loss of T2' signal intensity in L0 (-15.7%), followed by LG (-10.5%) and ST (-8.0%). CONCLUSIONS: The implementation of BOLD imaging in acute stroke MRI offers a noninvasive estimation of the O2 utilization and is able to add additional information concerning the present metabolic state of the threatened brain tissue. The changes in T2' intensity are visually noticeable in the reconstructed T2' images and provide a better estimation of the real penumbra.

Acute Disease↗

PubMed2006

Low-grade and anaplastic gliomas: differences in architecture evaluated with diffusion-tensor MR imaging.

PURPOSE: To prospectively evaluate whether diffusion-tensor magnetic resonance (MR) imaging depicts differences in World Health Organization (WHO) grade II and III glial brain tumors on the basis of tumor architecture and peritumoral tract invasion. MATERIALS AND METHODS: The study protocol was approved by the local ethics committee, and written informed consent was obtained. Diffusion-tensor MR imaging was performed in 23 patients (15 men, eight women; mean age, 47 years) with histologically confirmed brain gliomas. Eleven of the 23 tumors were low-grade gliomas (WHO grade II) and 12 were anaplastic gliomas (WHO grade III). Regions of interest were placed in the tumor center, tumor border, normal-appearing white matter (NAWM) adjacent to the tumor, and NAWM of the contralateral hemisphere. fractional anisotropy (FA) ratios were calculated for regions of interest in relation to the NAWM of the contralateral hemisphere. Pairwise comparisons were performed by using the Mann-Whitney U test. RESULTS: Median FA ratios for grade II versus grade III gliomas were 0.406 versus 0.405, respectively, for tumor center, 0.733 versus 0.449, respectively, for tumor border, and 0.962 versus 0.943, respectively, for NAWM adjacent to the tumor. Differences in FA ratio between low-grade and high-grade tumors were significant in the tumor border only (P = .01). Differences in FA ratio were not significant between low-grade and high-grade gliomas in the tumor center or in the NAWM adjacent to the tumor. CONCLUSION: The periphery of low-grade gliomas contains a considerable amount of preserved fiber tracts. In high-grade gliomas, however, most of these tracts are disarranged. Low FA ratios in the tumor center are consistent with a high degree of disorganization of myelinated fiber tracts in the center of both low-grade and high-grade gliomas.

Adult↗

PubMed2006

Outcome and symptomatic bleeding complications of intravenous thrombolysis within 6 hours in MRI-selected stroke patients: comparison of a German multicenter study with the pooled data of ATLANTIS, ECASS, and NINDS tPA trials.

BACKGROUND AND PURPOSE: We compared outcome and symptomatic bleeding complications of intravenous tissue plasminogen activator (IV-tPA) within 6 hours of symptom onset in MRI-selected patients with acute middle cerebral artery infarction with the pooled data of the large stroke tPA trials. METHODS: Patients were examined by perfusion-weighted and diffusion-weighted imaging < or =6 hours. Within 3 hours, patients were treated according to Second European-Australasian Acute Stroke Study (ECASS II) criteria. After 3 to 6 hours, treatment with IV-tPA was performed based on MRI findings. Favorable outcome was assessed after 90 days using a dichotomized modified Rankin scale score of 0 to 1. Intracerebral bleeding complications were assessed on follow-up MRI or computed tomography. Data were compared with the pooled placebo and pooled tPA patients of the ATLANTIS, ECASS, and National Institute of Neurological Disorders and Stroke (NINDS) tPA trials. RESULTS: From 174 MRI-selected tPA patients, 62% (n=108) were treated in < or =3 hours and 38% (n=66) after 3 to 6 hours. Favorable outcome was more frequent in MRI-selected tPA patients (48% [95% CI, 39 to 54]) compared with pooled placebo (33% [95% CI, 31 to 36]; P<0.001) and pooled tPA patients (40% [95% CI, 37 to 42]; P=0.046). Odds ratios for favorable outcome in the MRI-selected tPA group were 1.82 (1.32 to 2.51) compared with the pooled placebo and 1.39 (1.01 to 1.92) compared with the pooled tPA group. The rate of symptomatic intracerebral hemorrhage in MRI-selected tPA patients (3% [95% CI, 0 to 5]) was lower than in the pooled tPA group (8% [95% CI, 7 to 10]; P=0.012) and comparable to the pooled placebo group (2% [95% CI, 1 to 3]; P=0.392). CONCLUSIONS: This study supports that it is safe and effective to expand the time window for IV-tPA up to 6 hours in patients with tissue at risk as defined by MRI.

Adolescent↗

PubMed2006

A multicenter reproducibility study of single-voxel 1H-MRS of the medial temporal lobe.

Proton magnetic resonance spectroscopy ((1)H-MRS) has provided evidence for a reduction of N-acetyl-aspartate (NAA) in the medial temporal lobe (MTL) in cerebral disorders such as Alzheimer's Disease. Within the (1)H-MRS study of the German Research Network on Dementia, we determined the multicenter reproducibility of single-voxel (1)H-MRS of the MTL. At five sites with 1.5T MR systems, single-voxel (1)H spectra from the MTL of an identical healthy subject were measured. The same subject was also examined at one of the sites five times to assess intracenter stability. The protocol included water-suppressed spectra with TE 272 ms and TE 30 ms and unsuppressed spectra for absolute quantification of metabolite concentrations. The intracenter reproducibility of absolute NAA concentration, expressed as coefficient of variation (CV), was 1.8%. CV for the concentrations of creatine (Cr), choline (Cho), and myoinositol (MI) and for the ratios NAA/Cr, NAA/Cho, and MI/NAA varied by 11-16%. Intercenter CV was 3.9% for NAA and were below 10% for all other metabolites and metabolic ratios. Our study demonstrates that quantitative assessment of NAA with single-voxel MRS can be performed with high intercenter reproducibility. This is the basis for applying (1)H-MRS in large-scale early recognition and treatment studies in MTL affecting disorders.

Adult↗

PubMed2006

Cerebral vasculitis following oral methylphenidate intake in an adult: a case report.

Methylphenidate is structurally and functionally similar to amphetamine. Cerebral vasculitis associated with amphetamine abuse is well documented, and in rare cases ischaemic stroke has been reported after methylphenidate intake in children. We report the case of a 63-year-old female who was treated with methylphenidate due to hyperactivity and suffered from multiple ischaemic strokes. We consider drug-induced cerebral vasculitis as the most likely cause of recurrent ischaemic strokes in the absence of any pathological findings during the diagnostic work-up. We conclude that methylphenidate mediated vasculitis should be considered in patients with neurological symptoms and a history of methylphenidate therapy. This potential side-effect, though very rare, represents one more reason to be very restrictive in the use of methylphenidate.

Acute Disease↗

PubMed2005

Motor strokes: the lesion location determines motor excitability changes.

BACKGROUND AND PURPOSE: The purpose of this research was to investigate the impact of lesion location on motor excitability and motor performance. METHODS: We studied patients with pure motor strokes in 4 different brain areas: motor cortex lesions (n=7), striatocapsular lesions (n=13), lacunar lesions of the internal capsule (n=13), and paramedian pontine lesions (n=10). Motor performance tests included the 9-hole-peg test and grip strength recordings. Motor excitability was determined by transcranial magnetic stimulation. Motor thresholds, stimulus-response curves, silent periods, motor cortical inhibition, and facilitation were investigated. RESULTS: The 4 groups were clinically similar but showed major differences in motor excitability. Only motor cortex lesions had a loss of intracortical inhibition in the affected hemisphere. In the internal capsule lesion group and the pontine lesion group, stimulus-response curves were depressed on the affected side. All of the subcortical lesions showed a prolongation of the silent period in the paretic side. Motor thresholds were predominantly elevated in the lesioned hemisphere of patients with internal capsule or pontine lesions. Motor performance was correlated with silent period duration in internal capsule lesions and with motor thresholds in internal capsule and pontine lesions. CONCLUSIONS: Motor cortex lesions exhibited deficient inhibitory properties. In contrast, subcortical lesions displayed an enhancement of inhibition. Internal capsule and pontine lesions affecting the corticospinal tract on different levels particularly impaired neuronal recruitment. Our results suggest that the lesion location determines a specific pattern of motor excitability changes.

Aged↗

PubMed2005

Outcome and severe hemorrhagic complications of intravenous thrombolysis with tissue plasminogen activator in very old (> or =80 years) stroke patients.

BACKGROUND AND PURPOSE: Information on safety and efficacy of intravenous thrombolysis with tissue plasminogen activator (tPA) (IV-tPA) in very old acute ischemic stroke (AIS) patients is scarce. We studied outcome and severe hemorrhagic complications in patients aged 80 and older. METHODS: We analyzed data of AIS patients, treated with IV-tPA, in 3 German stroke centers. Neurologic deficit on admission was assessed using the National Institutes of Health Stroke Scale (NIHSS). Outcome was assessed after 90 days using the Modified Rankin Scale (MRS), and favorable outcome was defined as a MRS score of 0 to 1. Severe intracerebral bleeding complications were assessed on follow-up magnetic resonance imaging or cranial computed tomography. Data were compared between patients <80 years of age and patients aged > or =80 years. RESULTS: A total of 228 patients were treated with IV-tPA; 38 (16%) were 80 years or older. There was no difference in NIHSS on admission or onset to treatment time between younger and older patients. Less patients > or =80 years of age achieved a favorable outcome (26.3 versus 46.8%, P=0.021), and mortality was higher in older patients (21.1 versus 5.3%, P=0.004). There was no difference in the rate of parenchymal hemorrhage (6.3%<80 years versus 5.3%> or =80 years, P=1.000) and symptomatic intracerebral hemorrhage (2.6%<80 years versus 2.6%> or =80 years, P=1.000) between both groups. CONCLUSIONS: There is no increase in severe intracerebral hemorrhage after IV-tPA in very old patients, but outcome is worse as compared with younger patients. There is no evidence to exclude ischemic stroke patients from thrombolysis based on a predefined age threshold.

Age Factors↗

PubMed2005

Magnetic resonance imaging and clinical patterns of patients with 'spectacular shrinking deficit' after acute middle cerebral artery stroke.

BACKGROUND: Rapid resolution of neurological deficits after severe middle cerebral artery (MCA) stroke has been coined spectacular shrinking deficit (SSD). We studied clinical and MRI patterns in patients with SSD. METHODS: Patients with acute MCA stroke <6 h were examined by stroke MRI (perfusion- and diffusion-weighted imaging (PWI, DWI), MR angiography (MRA)) at admission, day 1 and day 7. SSD was defined as a > or =8-point-reduction of neurological deficit in the National Institute of Health Stroke Scale (NIHSS) to a score of < or =4 within 24 h. PWI and DWI lesion volumes were measured on ADC (ADC < 80%) and time to peak maps (TTP > +4 s). Recanalization was assessed by MRA after 24 h. Final infarct volumes were defined on T2 weighted images at day seven. Outcome was assessed after 90 days using modified Rankin Scale (mRS) and Barthel Index (BI). RESULTS: SSD was present in 14 of 104 patients. Initial DWI and PWI lesion volumes were smaller in SSD patients - ADC < 80%: 8.9 (4.3-20.5) vs. 30 (0-266.7) ml; TTP > +4 s: 91.6 (29.7-205.8) vs. 131.5 (0-311.5) ml. Early recanalization was associated with SSD resulted in smaller final infarct volumes (11.9 (2.4-25.9) vs. 47.7 (1.2-288.5)). All SSD patients were independent at day 90 (mRS 0 (0-2); BI 100). CONCLUSION: The clinical syndrome of SSD is reflected by a typical MRI pattern with small initial DWI and PWI lesion volumes, timely recanalization and small final infarct volumes.

Acute Disease↗

PubMed2005

Aggressive therapy with intravenous abciximab and intra-arterial rtPA and additional PTA/stenting improves clinical outcome in acute vertebrobasilar occlusion: combined local fibrinolysis and intravenous abciximab in acute vertebrobasilar stroke treatment (FAST): results of a multicenter study.

BACKGROUND AND PURPOSE: A combined therapy of local recombinant tissue plasminogen activator (rtPA) fibrinolysis and intravenous Abciximab platelet inhibition with additional percutaneous transluminal angioplasty (PTA)/stenting may improve recanalization and neurological outcome in patients with acute vertebrobasilar occlusion. METHODS: Combined FAST therapy consisted on intravenous bolus of Abciximab (0.25 mg/kg) followed by a 12-hour infusion therapy (0.125 microg/kg per minute) and low-dose intra-arterial rtPA (median dosage: 20 mg, FAST cohort: N=47). The results were compared with a retrospective cohort, treated by intraarterial rtPA monotherapy (median dosage: 40 mg, rtPA cohort, N=41). Additional PTA/stenting was performed in case of severe residual stenosis. Recanalization success was classified according to the Trials in Myocardial Infarction (TIMI) criteria: TIMI0/1, failed recanalization; TIMI2/3, successful recanalization. Bleeding complications were evaluated according to severe extracerebral hemorrhage (ECH), asymptomatic intracerebral hemorrhage (AIH), and symptomatic intracerebral hemorrhage (SIH). RESULTS: Overall bleeding rate was higher under the combined therapy, but the SIH rate did not differ (FAST versus rtPA: ECH, 3% versus 0%; AIH, 32% versus 22%; SIH 13% versus 12%). Additional PTA/stenting was performed in 14 (FAST) versus 5 (rtPA) patients. TIMI2/3 recanalization rate was similar (FAST, 72%; rtPA, 68%), but TIMI3 rate was remarkably higher under combined therapy (FAST, 45%; rtPA, N=22%). Neurologic outcome appeared better under combined therapy (FAST versus rtPA: favorable outcome rate: 34% versus 17%) with a significantly lower mortality rate (FAST versus rtPA: 38% versus 68%; P=0.006). These results were consistent for embolic and atherothrombotic occlusions. CONCLUSIONS: Combined therapy of intravenous Abciximab and half dose intra-arterial rtPA with additional PTA/stenting appears to improve neurologic outcome in acute vertebrobasilar occlusion despite an increase of overall bleeding complications.

Abciximab↗

PubMed2005

Reperfusion after severe local perfusion deficit precedes hemorrhagic transformation: an MRI study in acute stroke patients.

BACKGROUND: We applied magnetic resonance imaging to analyze the degree of local diffusion and perfusion abnormalities and the status of reperfusion in regions with subsequent hemorrhagic transformation (HT). METHODS: 51 patients with acute ischemic stroke were studied by diffusion- and perfusion-weighted imaging within 3.0 +/- 0.8 h, on day 1 and days 5-8. After realignment of the image data sets, the parameter maps of the apparent diffusion coefficient (ADC), cerebral blood flow (CBF) and cerebral blood volume (CBV), and mean transit time were analyzed in the area of subsequent HT. The degree of local diffusion and perfusion impairment in the HT area was compared with the entire diffusion and perfusion abnormality. Reperfusion status was separately assessed for the entire perfusion abnormality and the HT area. RESULTS: HT was observed in 19/51 patients (37.2%) within 8 days after symptom onset. Areas destined for HT revealed a more severe decrease in ADC (to 70 +/- 13%; p < 0.01), CBV (to 31 +/- 26%; p < 0.001) and CBF (to 28 +/- 19%; p < 0.001) compared to the entire perfusion abnormality. Local reperfusion in the HT area was seen in 18/19 patients. The presence of HT did not coincide with a worse clinical outcome. DISCUSSION: HT is the result of reperfusion in the region with the most severe local perfusion impairment and does not influence the neurological outcome.

Age Factors↗

PubMed2005

Unenhanced CT and acute stroke physiology.

Unenhanced CT remains the most widely used imaging technique and is the standard of care for acute stroke evaluation. Early ischemic signs (EIS) within the first 3 to 6 hours of symptom onset (eg, parenchymal hypodensity, sulcal effacement, and dense vessel) have been advocated as a triage tool for thrombolytic therapy. Recent studies have challenged the relevance of these EIS within 3 hours of stroke onset, with advanced MR and CT methods increasingly competing with unenhanced CT as the primary imaging modality for acute ischemia. Nonetheless, the insights regarding acute stroke physiology provided by studying the CT evolution of early ischemic signs continue to be valuable for the informed interpretation of all stroke images. It is these insights that comprise the topic of this article.

Acute Disease↗

PubMed2005

Emergency carotid artery stenting in persistent hemodynamic deficit associated with severe carotid stenosis.

MR imaging in a 73-year-old man presenting with hemispheric stroke revealed a subcortical diffusion-weighted imaging lesion associated with a high-grade stenosis of the proximal internal carotid artery, which suggested hemodynamic infarction. Collateral supply was absent. After failure of conservative therapy, successful unprotected carotid artery stent placement (CAS) was performed followed by a complete neurologic recovery. Emergency CAS should be considered in acute stroke patients with severe hemodynamic impairment if conservative treatment options are not successful.

Aged↗

PubMed2005

Tissue at risk is overestimated in perfusion-weighted imaging: MR imaging in acute stroke patients without vessel recanalization.

BACKGROUND AND PURPOSE: The volume of decreased cerebral blood flow (CBF) in acute stroke perfusion-weighted imaging frequently overestimates final infarct volume. We hypothesized that surviving tissue exists even in patients without recanalization and tried to determine perfusion thresholds from initial MR imaging. METHODS: Stroke MR imaging including MR angiography was carried out at days 0, 1, and 7 after stroke onset in 19 patients without recanalization at least until day 1. The following lesions were defined: L0 = diffusion restriction at day 0; LG1 = lesion growth until day 1; LG7 = lesion growth until day 7; ST7 = initially hypoperfused, but surviving tissue. These lesions were transferred on initial MR imaging within 4.7 hours and perfusion values at day 0 were determined. RESULTS: Median lesion volume L0 at day 0 was 18.2 mL and increased to 39.4 and 43.8 mL at days 1 and 7. Volume of decreased rCBF not progressing to infarction was 148.5 mL (ST7). Mean ST7 perfusion values were different from L0 and LG1, but only mean relative cerebral blood volume (rCBV) was different from LG7, discriminating survival against death of tissue. A threshold value of 0.82 CBV for death versus survival was determined with a sensitivity of 0.56 and specificity of 0.95. Carotid T occlusions showed the greatest potential of lesion growth. CONCLUSION: Even when vessel occlusion persists, hypoperfused tissue on MR imaging does not necessarily progress toward infarction. The most conclusive inferences can be drawn from CBV images. The site of arterial occlusion also determines progression to infarction.

Adult↗

PubMed2005

Vascular occlusion sites determine differences in lesion growth from early apparent diffusion coefficient lesion to final infarct.

BACKGROUND AND PURPOSE: Occlusion of major cerebral arteries is the primary source of tissue damage in ischemic stroke and the target of thrombolytic therapy. We hypothesized that large infarcts in more proximal vascular occlusions correspond with substantially increased ischemic lesions shown on initial apparent diffusion coefficient (ADC) maps. METHODS: Initial ADC lesions in 120 patients with acute ischemic stroke were analyzed within 6 hours of stroke onset. Patients were categorized on the basis of vascular occlusion, as shown on MR angiography. Lesion volumes were determined by using manual delineation (ADC(man)) and a threshold method for ADC values (<550 x 10(-9) mm(2)/s(-1), ADC(<550)). Infarct volumes were analyzed by using T2-weighted (n = 109) or CT (n = 11) images obtained on days 5-8. RESULTS: Median lesion volumes for ADC(<550), ADC(man), and infarcts, respectively, were as follows: proximal internal carotid artery (ICA)/middle cerebral artery (MCA) occlusions, 10, 23, and 32 cm(3); carotid-T occlusions, 11, 37, and 138 cm(3); MCA trunk occlusions, 11, 27, and 44 cm(3)); and MCA branch occlusions 8, 27, and 21 cm(3). Initial ADC lesion volumes were different only between the carotid T and the MCA branch (P < .05). On days 5-8, infarct volumes decreased from proximal to distal sites (P < .05), with the exception of MCA trunk versus proximal ICA/MCA occlusions. Recanalization rate in carotid-T occlusion was significantly lower than those of all other occlusion types. CONCLUSION: Initial ADC lesions can be small, even in patients with proximal vascular occlusions. These patients develop considerably large infarctions, suggesting a high potential for infarct growth. This growth might be averted with improved early recanalization of proximal vascular occlusions.

Arterial Occlusive Diseases↗

PubMed2004

Screening for cerebellopontine angle tumors: is a CISS sufficient?

This study attempted to evaluate the reliability of ultra-thin T2-weighted imaging with a constructive interference in steady state (CISS) sequence as a screening method for tumors in the cerebellopontine angle. A retrospective study of 200 CISS examinations was made by five investigators. The examinations were inspected on plain film supported by clinical information. The interobserver agreement in the detection of lesions was analyzed. Fourteen cases (50% of the contrast-enhancing lesions) were rated pathological by all five readers. One case of subarachnoid lymphoma infiltration was overlooked by all five readers. Overall, six pathological lesions (median = 6, range 1-9) were not identified. The interobserver agreement for all pathological lesions was moderate (kappa=0.53; 95% CI, 0.43-0.62). The mean sensitivity was 77.8% (range 72.0-96.3%), and the mean specificity was 97.6% (range 94.8-100%). The median sensitivity for pathological lesions concerning only patients with acute sensorineural hearing loss (n=148, patients with 20 contrast-enhancing cases) was 86.6% (range 80-100%), and median specificity was 95.2% (range 84.4-96.9%) with a moderate interobserver agreement (kappa=0.55; 95% CI, 0.44-0.66). In our opinion the CISS sequence is a valuable addition to the examination of the cerebellopontine angle but lacks sufficient reliability for the detection of tumors of small size or of tumors adjacent to brain parenchyma or the temporal bone.

Cerebellar Neoplasms↗

PubMed2004

Are there time-dependent differences in diffusion and perfusion within the first 6 hours after stroke onset?

BACKGROUND AND PURPOSE: Stroke heterogeneity in computed tomography-based studies has been attributed as main cause for missing efficacy of intravenous tissue plasminogen activator (tPA) therapy within 3 to 6 hours. We investigated early time-dependent differences in acute stroke pathophysiology by multiparametric magnetic resonance imaging (MRI). METHODS: Stroke MRI of 112 acute ischemic stroke patients within <6 hours were dichotomized into a <3-hour group (n=52) and a 3- to 6-hour group (n=60). Infarct volume was determined on days 5 to 8. Lesion volumes were determined for apparent diffusion coefficient (ADC_man) and the subregion with ADC values <550x10(-9) mm/s2 (ADC <550), and for the time-to-peak (TTP) delay of 2 to 4 seconds, 4 to 6 seconds, 6 to 8 seconds, and >8 seconds. A subsample analysis was performed for occlusions of the middle carotid artery (MCA) trunk (n=36) and MCA branches (n=30), and for all patients treated by intravenous tPA (n=70). RESULTS: ADC and TTP lesion volumes were not different within <3 hours compared with volumes at 3 to 6 hours. In patients receiving intravenous tPA (n=70), there were no significant differences in ADC_man, TTP >2 seconds, and infarct volume (days 5 to 8) between the 2 groups. There was a greater proportion of ADC <550/ADC_man, which was most pronounced in patients with MCA trunk occlusions after 3 to 6 hours and a larger mismatch in the <3-hour group compared with that of the 3- to 6-hour group. In MCA branch occlusions, there was a less severe TTP delay after 3 to 6 hours. However, all differences missed the significance level (P=0.05) after correction for multiple testing. CONCLUSIONS: We observed no significant time-dependent differences within 6 hours after stroke onset in degree and volume of diffusion and perfusion impairment. An exclusion from intravenous tPA solely based on a rigid 3-hour time window seems unjustified in MRI-confirmed ischemic stroke.

Acute Disease↗

PubMed2004

Transient ischemic attacks before ischemic stroke: preconditioning the human brain? A multicenter magnetic resonance imaging study.

BACKGROUND AND PURPOSE: We investigated whether transient ischemic attacks (TIAs) before stroke can induce tolerance by raising the threshold of tissue vulnerability in the human brain. METHODS: Sixty-five patients with first-ever ischemic territorial stroke received diffusion- and perfusion-weighted MRI within 12 hours of symptom onset. Epidemiological and clinical data, lesion volumes in T2, apparent diffusion coefficient (ADC) maps and perfusion maps, and cerebral blood flow and cerebral blood volume values were compared between patients with and without a prodromal TIA. RESULTS: Despite similar size and severity of the perfusion deficit, initial diffusion lesions tended to be smaller and final infarct volumes were significantly reduced (final T2: 9.1 [interquartile range, 19.7] versus 36.5 [91.2] mL; P=0.014) in patients with a history of TIA (n=16). This was associated with milder clinical deficits. CONCLUSIONS: The beneficial effect of TIAs on lesion size in ADC and T2 suggests the existence of endogenous neuroprotection in the human brain.

Blood Flow Velocity↗

PubMed2004

Stroke magnetic resonance imaging is accurate in hyperacute intracerebral hemorrhage: a multicenter study on the validity of stroke imaging.

BACKGROUND AND PURPOSE: Although modern multisequence stroke MRI protocols are an emerging imaging routine for the diagnostic assessment of acute ischemic stroke, their sensitivity for intracerebral hemorrhage (ICH), the most important differential diagnosis, is still a matter of debate. We hypothesized that stroke MRI is accurate in the detection of ICH. To evaluate our hypotheses, we conducted a prospective multicenter trial. METHODS: Stroke MRI protocols of 6 university hospitals were standardized. Images from 62 ICH patients and 62 nonhemorrhagic stroke patients, all imaged within the first 6 hours after symptom onset (mean, 3 hours 18 minutes), were analyzed. For diagnosis of hemorrhage, CT served as the "gold standard." Three readers experienced in stroke imaging and 3 final-year medical students, unaware of clinical details, separately evaluated sets of diffusion-, T2-, and T2*-weighted images. The extent and phenomenology of the hemorrhage on MRI were assessed separately. RESULTS: Mean patient age was 65.5 years; median National Institutes of Health Stroke Scale score was 10. The experienced readers identified ICH with 100% sensitivity (confidence interval, 97.1 to 100) and 100% overall accuracy. Mean ICH size was 17.3 mL (range, 1 to 101.5 mL). The students reached a mean sensitivity of 95.16% (confidence interval, 90.32 to 98.39). CONCLUSIONS: Hyperacute ICH causes a characteristic imaging pattern on stroke MRI and is detectable with excellent accuracy. Even raters with limited film-reading experience reached good accuracy. Stroke MRI alone can rule out ICH and demonstrate the underlying pathology in hyperacute stroke.

Acute Disease↗