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Blockage of healthy blood vessels by blood clots can lead to serious or even life-threatening complications. The use of a combined ultrasound (US) and photoacoustic (PA) imaging was explored for blood clot monitoring during microbubble-assisted sonothrombolysis. PA imaging is an emerging hybrid imaging modality that has garnered the attention of the biomedical imaging community in recent years. It enables the study of the composition of a blood clot due to its sensitivity toward optical absorption. Here, in vitro imaging of the side of a blood clot facing the microbubbles was done over time. The US and PA signal-to-noise (SNR) ratio value changes during microbubble-assisted sonothrombolysis were studied for two different local environments: blood clot in deionized water and blood clot in blood. In the first case, US and PA SNR values increased by 4.6% and reduced by 20.8%, respectively after 30 min of sonothrombolysis treatment. After 10 min of sonothrombolysis treatment of the blood clot in blood, the US and PA SNR values increased by 7.7% and 38.3%, respectively. The US and PA SNR value changes were recorded in response to its local environment. This technique can be used to determine the final composition of the blood clot which may, in turn, help in the administration of clot-dissolving drugs. MOE (Min. of Education, S’pore) Published version

BACKGROUND: The benefit of intravenous tissue plasminogen activator (tPA) given within 3 h of acute ischaemic stroke to patients over 80 years of age is uncertain. AIM: To examine the clinical characteristics and complications and the predictors of outcome after intravenous tPA treatment in patients aged > or = 80 years. METHODS: Data (n = 1135) prospectively collected from the Canadian Alteplase for Stroke Effectiveness Study were reviewed and patients aged > or = 80 years (n = 270) treated with intravenous tPA for acute ischaemic stroke were compared with those aged or = 80 years and or = 80 years and in 40% of those or = 80 years than in those aged or = 80 years, stroke severity, baseline Alberta Stroke Program Early CT Score and glucose level were found to be the major independent predictors of outcome. CONCLUSION: In carefully selected elderly patients, the use of intravenous tPA was not found to be associated with an increased risk of symptomatic intracerebral haemorrhage. Age-related differences were seen in the clinical characteristics and outcome in the elderly population.

Several studies indicate that only a small proportion of patients with acute ischaemic stroke are treated with intravenous thrombolysis. Indications and contraindications for this treatment are usually based on the inclusion and exclusion criteria of randomised clinical trials. The trial context of these criteria hampers implementation in real life settings. We therefore aimed to obtain specialist opinion in a Delphi consensus on these contraindications.We used the Delphi approach on an international group of specialists in the field of thrombolysis. Inclusion and exclusion criteria were reworded into 18 quantitatively phrased propositions. Feedback consisted of the median score, interquartile range and the panellist's own score in the previous round. For each item, we defined consensus as the achievement of an interdecile range within two prespecified clinically relevant units.Thirty-one specialists participated in the first round and 30 completed all three rounds. Consensus was reached on 12 of the 18 propositions: previous ischaemic stroke, head trauma and gastrointestinal tract bleeding should not have taken place earlier than 1.5 months, 2 months and 14 days, respectively; the severity of the neurological deficit is defined as a National Institutes of Health Stroke Scale (NIHSS) score of 2-3 or more, and blood pressure level should not be185/110 mmHg; platelet count should be90x10(12)/l, glucose levels 2.7-22 mmol/l, international normalised ratio1.5 and activated partial thromboplastin time50 s. No consensus was reached on propositions concerning the stroke onset to treatment time, patient's age, recent medical procedures, spontaneous improvement rate and blood pressure treatment.We present specialists' opinion on contraindications for intravenous thrombolysis in ischaemic stroke. The results of this study may be relevant for routine clinical practice as they may help to increase the number of treated patients.

Background: The mismatch between perfusion and diffusion lesions on magnetic resonance perfusion-weighted imaging (PWI)/diffusion-weighted imaging (DWI) may help identify patients for thrombolysis. Evidence underlying this hypothesis was assessed. Methods: All papers describing magnetic resonance PWI/DWI findings in patients with acute ischaemic stroke, and their functional and/or radiological outcome at 1 month, with or without thrombolysis were systematically reviewed. Results: 11 papers fulfilled the inclusion criteria. Among these, there were 5 different mismatch definitions and at least 7 different PWI methods. Only 3 papers including 61 patients with and 18 without mismatch provided data on mismatch, outcome and influence of thrombolysis. Mismatch ( v no mismatch) without thrombolysis was associated with a non-significant twofold increase in the odds of infarct expansion (odds ratio (OR) 2.2, 95% confidence interval (CI) 0.34 to 14.1), which did not change with thrombolysis (OR 2.0, 95% CI 0.37 to 10.9). Half of the patients without mismatch also had infarct growth (with or without thrombolysis). No data were available on functional outcome. Conclusions: Standardised definitions of mismatch and perfusion are needed. Infarct growth may occur even in the absence of mismatch. Currently, data available on mismatch are too limited to guide thrombolysis in routine practice. More data are needed from studies including patients with and without mismatch, and randomised treatment allocation, to determine the role of mismatch.

To determine the safety, efficacy, and predictors of favourable outcome of intra-arterial thrombolysis in acute stroke attributable to internal carotid "T"occlusionThe authors analysed 24 consecutive patients with T occlusions of the internal carotid artery treated by local intra-arterial thrombolysis using urokinase.The median baseline National Institutes of Health Stroke Scale was 19. The average time from symptom onset to treatment was 237 minutes. Four patients (16.6%) had a favourable (modified Rankin Scale score (mRS/=2)) and 10 patients (41.7%) a poor outcome (mRS 3 or 4) after three months. Ten patients (41.7%) died. One symptomatic intracerebral haemorrhage (4.2%) occurred. Partial recanalisation of the intracranial internal carotid artery was achieved in 15 (63%), of the middle cerebral artery in four (17%), and of the anterior cerebral artery in eight patients (33%). Complete recanalisation never occurred. Sufficient leptomeningeal collaterals as seen on arteriography (p=0.02) and age60 years (p=0.012) were the only predictors of favourable clinical outcome.Acute stroke attributable to carotid T occlusion remains a condition with a generally poor prognosis even when intra-arterial thrombolysis is performed. Favourable outcome was seen only in patients with sufficient leptomeningeal collaterals.

Objectives: The astroglial protein S100B is a marker of cerebral tissue damage. This study investigated whether the serum kinetic of S100B may serve as a surrogate marker of successful clot lysis and early recanalisation (

Owing to the fear of an increased bleeding risk, thrombolytic therapy is withheld from many patients with acute stroke80 years of age.To analyse the risk for symptomatic intracranial haemorrhage (sICH), morbidity and mortality after thrombolytic therapy in octogenarians focusing, in particular, on whether patients selected using magnetic resonance imaging (MRI) had a better risk:benefit ratio.The prospectively collected single-centre data of all patients treated with systemic thrombolytic therapy for acute ischaemic stroke since 1998 (n = 468) were reviewed, and patientsor = 80 years (n = 90) were compared with those aged80 years (n = 378). In addition, the group of octogenarians was analysed with respect to initial imaging modality.The overall rate of sICH in the octogenarians was 6.9%, compared with 5.3% in younger patients (p = 0.61). In older patients selected by computed tomography, the rate of sICH was 9.4%; no patient selected by MRI had sICH (p = 0.10). Mortality in the octogenarians selected by computed tomography was 29.7% after 3 months as compared with 26.9% in the patients selected by MRI (p = 1.0). 20.3% of the octogenarians selected by computed tomography and 15.4% of those selected by MRI had a favourable outcome (modified Rankin scaleor = 1) after 3 months (p = 0.77).Compared with younger patients, octogenarians do not have an increased risk of sICH. The use of MRI to select octogenarians for thrombolytic therapy seemed to decrease the risk of sICH, but did not influence the overall outcome after 3 months.

Objective: To establish the validity of visual interpretation of immediately processed perfusion computed tomography (CT) maps in acute stroke for prediction of final infarction. Methods: Perfusion CT studies acquired prospectively were reprocessed within six hours of stroke onset using standard CT console software. Four contiguous 5 mm thick images were obtained and maps of time to peak (TTP) and cerebral blood volume (CBV) generated. Volumes of lesions identified only by visual inspection were measured from manually drawn regions of interest. Volumes of tissue with prolonged TTP or reduced CBV were compared with independently calculated volume of infarction on non-contrast CT (NCCT) at 24–48 hours, and with clinical severity using the NIHSS score. Arterial patency at 24–48 h was included in analyses. Results: Studies were analysed from 17 patients 150 minutes (median) after stroke onset. Volume of tissue with prolonged TTP correlated with initial NIHSS ( r = 0.62, p = 0.009), and with NCCT final infarct volume when arterial occlusion persisted ( r = 0.953, p = 0.012). Volume of tissue with reduced CBV correlated with final infarct volume if recanalisation occurred ( r = 0.835, p = 0.001). Recanalisation was associated with lower 24 h NIHSS score (6 (IQR, 5 to 9.5) v 19 (18 to 26), p = 0.027), and in 10 patients given rtPA for MCA M1 occlusion, with lower infarct volume (73 v 431 ml, p = 0.002). Conclusions: Visual evaluation of TTP and CBV maps generated by standard perfusion CT software correlated with 24–48 hour CT infarct volumes. Comparison of TTP and CBV maps yields information on tissue viability. Perfusion CT represents a practical technique to aid acute clinical decision making. Recanalisation was a crucial determinant of clinical and radiological outcome.

Background: Several case series and a recent meta-analysis indicate that intra-arterial thrombolysis (IAT) is effective for the treatment of acute central retinal artery occlusion (CRAO). Methods: A total of 37 patients with acute monocular blindness because of unilateral thromboembolic CRAO were treated with IAT using urokinase within six hours of the onset of symptoms. Visual outcome was compared with a control group of 19 patients, also seen within six hours, who did not undergo thrombolytic treatment. In both groups some patients were treated by paracentesis and/or acetazolamide. Predictors of visual outcome were evaluated. Results: Visual improvement was more likely with IAT (p = 0.01) as were the chances to regain visual acuity of >0.6 significantly better (p = 0.04): 8/37 patients (22%) regained visual acuity of >0.6 in the IAT group and none (0/19) in the control group. Younger patients were more likely to regain some vision with (p = 0.012) or without IAT (p = 0.026). Three patients had minor treatment related cerebral ischaemic events, two had transient ischaemic attacks and one a minor stroke. There were no haemorrhagic complications. Conclusions: This series of patients with CRAO demonstrated that IAT enhanced the chances of visual improvement compared with conventional treatment only. Furthermore, younger patients have a better chance to achieve some visual recovery.

Factors that predict basilar artery occlusion outcome Acute basilar artery occlusion is a known cause of brain stem infarction that is often fatal. The most physiological way of treating this condition is recanalisation of the occluded artery to revascularise endangered ischemic brain. Thrombolysis by intravenous recombinant tissue plasminogen activator (rtPA) brings substantial clinical benefit in acute stroke, however, a large number of patients do not respond to this treatment. Intra-arterial thrombolysis may improve overall outcome in patients with basilar artery occlusion but predicting benefit of therapy is still difficult in the individual patient. The crucial issue in acute basilar artery occlusion is defining the predictors for successful recanalisation and improved outcome. Arnold et al 1 (pp 857) have tried to define clinical and radiological predictors of recanalisation and outcome in acute basilar artery occlusion. They found that a low National Institutes of Health Stroke Scale (NIHSS) score and vessel recanalisation (as seen on the angiogram) were associated with a favourable outcome. Complete …