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  • Albers, Gregory W  (7)
  • Olivot, Jean-Marc  (7)
  • 2010-2014  (7)
  • 1
    Online Resource
    Online Resource
    Abstract 95: Regional Very Low Cerebral Blood Volume with Subsequent Local Reperfusion Predicts Hemorrhagic Transformation in Acute Ischemic Stroke
    Ovid Technologies (Wolters Kluwer Health) ; 2012
    In:  Stroke Vol. 43, No. suppl_1 ( 2012-02)
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 43, No. suppl_1 ( 2012-02)
    Abstract: Background and Purpose Regions of very low cerebral blood volume (VLCBV) on MR perfusion imaging have been shown to predict hemorrhagic transformation (HT) following stroke thrombolysis. We tested the hypothesis that local reperfusion in a region of VLCBV is a pre-requisite for hemorrhagic transformation using pooled imaging data from the EPITHET and DEFUSE studies. Methods Standard CBV maps were calculated and smoothed (Gaussian) to reduce noise. The volume of VLCBV was calculated within the acute Tmax 〉 4sec perfusion lesion using fully automated techniques and a range of VLCBV thresholds relative to CBV values in the non-stroke hemisphere. Receiver operating characteristic (ROC) analysis was used to determine the optimal definition and threshold of VLCBV to predict parenchymal hematoma (PH, ECASS definition). Regional reperfusion was assessed using co-registered subacute Tmax perfusion images (DEFUSE 3-6hrs post thrombolysis, EPITHET 3-5 days post thrombolysis/placebo). The risk of PH associated with VLCBV was assessed with and without exclusion of regions of VLCBV within persistently hypoperfused regions. Results Of 145 patients with baseline perfusion imaging, 22 (15.2%) had PH (13 PH1, 9 PH2). A VLCBV definition of either 〈 2.5 th percentile of the contralateral CBV distribution (VLCBV 〈 2.5pctile) or 〈 15% of the mean contralateral CBV (VLCBV 〈 15%) had similar performance in predicting PH (AUC 0.73 for both). To achieve sensitivity of 95% required a VLCBV 〈 2.5pctile threshold of 〉 2mL (specificity 47%) or a VLCBV 〈 15% threshold of 〉 0.5mL (specificity 41%). There were 130 patients with subacute perfusion imaging, at which time 15 (11.5%) had developed PH. A further 3 patients (without reperfusion at subacute MRI) later developed PH and were excluded as reperfusion status at the time of PH was unknown. In the remaining 127 patients, the AUC for PH increased from 0.77 to 0.92 (p 〈 0.001, VLCBV 〈 2.5pctile definition) when regions of VLCBV without reperfusion on subacute imaging were excluded. The specificity of the 〉 2mL threshold (VLCBV 〈 2.5pctile) increased from 46 to 75%, positive predictive value increased from 20 to 35%, likelihood ratio for PH increased from 1.9 to 4.0 (sensitivity and negative predictive value were both 100% in these 127 patients). No patient developed PH at the time of subacute imaging in the absence of local reperfusion, including one patient where reperfusion of basal ganglia infarction had occurred (with CBV normalisation) prior to thrombolysis. Conclusions Local reperfusion is a critical factor in determining the risk of HT associated with regional VLCBV. This is consistent with the hypothesis that the severe ischemia represented by VLCBV is associated with focal blood-brain-barrier disruption and potential HT should reperfusion subsequently occur. Assessment of VLCBV can be automated and may be useful in clinical risk-benefit decisions regarding thrombolysis.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/str.43.suppl_1.A95
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2012
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  • 2
    Online Resource
    Online Resource
    The Infarct Core is Well Represented by the Acute Diffusion Lesion: Sustained Reversal is Infrequent
    SAGE Publications ; 2012
    In:  Journal of Cerebral Blood Flow & Metabolism Vol. 32, No. 1 ( 2012-01), p. 50-56
    Details
    In: Journal of Cerebral Blood Flow & Metabolism, SAGE Publications, Vol. 32, No. 1 ( 2012-01), p. 50-56
    Abstract: Diffusion-weighted imaging (DWI) is commonly used to assess irreversibly infarcted tissue but its accuracy is challenged by reports of diffusion lesion reversal (DLR). We investigated the frequency and implications for mismatch classification of DLR using imaging from the EPITHET (Echoplanar Imaging Thrombolytic Evaluation Trial) and DEFUSE (Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution) studies. In 119 patients (83 treated with IV tissue plasminogen activator), follow-up images were coregistered to acute diffusion images and the lesions manually outlined to their maximal visual extent in diffusion space. Diffusion lesion reversal was defined as voxels of acute diffusion lesion that corresponded to normal brain at follow-up (i.e., final infarct, leukoaraiosis, and cerebrospinal fluid (CSF) voxels were excluded from consideration). The appearance of DLR was visually checked for artifacts, the volume calculated, and the impact of adjusting baseline diffusion lesion volume for DLR volume on perfusion-diffusion mismatch analyzed. Median DLR volume reduced from 4.4 to 1.5 mL after excluding CSF/leukoaraiosis. Visual inspection verified 8/119 (6.7%) with true DLR, median volume 2.33 mL. Subtracting DLR from acute diffusion volume altered perfusion—diffusion mismatch ( T max 〉 6 seconds, ratio 〉 1.2) in 3/119 (2.5%) patients. Diffusion lesion reversal between baseline and 3 to 6 hours DWI was also uncommon (7/65, 11%) and often transient. Clinically relevant DLR is uncommon and rarely alters perfusion—diffusion mismatch. The acute diffusion lesion is generally a reliable signature of the infarct core.
    Type of Medium: Online Resource
    ISSN: 0271-678X , 1559-7016
    URL: Article
    DOI: 10.1038/jcbfm.2011.102
    Language: English
    Publisher: SAGE Publications
    Publication Date: 2012
    detail.hit.zdb_id: 2039456-1
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  • 3
    Online Resource
    Online Resource
    Abstract W P175: Diagnostic Yield of Echocardiography in Patients Presenting with Transient Ischemic Attack
    Ovid Technologies (Wolters Kluwer Health) ; 2014
    In:  Stroke Vol. 45, No. suppl_1 ( 2014-02)
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 45, No. suppl_1 ( 2014-02)
    Abstract: Background: Transthoracic (TTE) or transesophageal (TEE) echocardiography is often performed to identify a cardioembolic (CE) source as part of the TIA evaluation. However, TTE/TEE can be difficult to obtain on an urgent basis, and the diagnostic yield in TIA remains undetermined. Methods: Patients with presumed TIA (defined as acute onset of focal symptoms lasting 〈 24 hours likely due to a vascular cause) within 48 hours after presentation were prospectively enrolled at 3 stroke centers. Data regarding clinical features, medical history, results of diagnostic testing including TTE/TEE, treatment at discharge, and 90-day outcome were recorded. TIA etiology was determined by the enrolling investigator from all available information. CE sources were defined using a modified version of the Causative Classification of Stroke system. Results: A total of 633 TIA patients were included. Mean age was 66 ± 15 years, 52% were male, and the median ABCD 2 score was 4 (IQR 3-5). The 90 day stroke rate was 2% (12/633). TIA mechanism was determined to be CE in 16% of subjects. Echocardiography was performed in 495 subjects (TTE alone in 444, TTE+TEE in 44, and TEE alone in 7). TTE revealed a CE source in 45/488 (9%) patients. TEE revealed a CE source in 17/51 (33%) patients, of whom 9 had either negative TTE or TTE was not performed. Therefore, the overall yield of TTE/TEE for a CE source was 54/495 (11%). The most common CE source detected on TTE/TEE was dilated cardiomyopathy; CE sources not detected on TTE/TEE consisted mostly of atrial fibrillation. Anticoagulation was initiated because of a CE source found on TTE/TEE in 19/495 (4%) patients. Of those who underwent an MRI, 169/495 (34%) were DWI+. Yield of both TTE and TEE tended to be higher in DWI+ compared to DWI- subjects (TTE: 17/146 [12%] vs 17/235 [7%], p=0.14; TEE: 12/27 [44%] vs. 1/15 [7%], p=0.01). Conclusions: TTE and TEE identify a CE source and prompt a change in antithrombotic regimen with sufficient frequency to consider their inclusion in the diagnostic evaluation of patients with TIA. The yield of these tests, particularly TEE, is higher in patients with diffusion restriction on MRI.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/str.45.suppl_1.wp175
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2014
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  • 4
    Online Resource
    Online Resource
    Abstract 92: MRI Patient Selection In Acute Stroke Trials: Implications For Sample Size
    Ovid Technologies (Wolters Kluwer Health) ; 2012
    In:  Stroke Vol. 43, No. suppl_1 ( 2012-02)
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 43, No. suppl_1 ( 2012-02)
    Abstract: Background: MRI selection of patients with acute stroke may reduce the required sample size for randomized controlled trials of interventions aimed at restoring blood flow. The Target Mismatch pattern has been proposed as a MRI-marker that can differentiate patients who are likely to benefit from reperfusion from those who will have no effect from or may be harmed by reperfusion. The Target Mismatch pattern is present in approximately 50% of stroke patients with a middle cerebral artery occlusion who present in the 3-6 hour time-window. The pattern is based on the following PWI and DWI criteria: ratio of Tmax 〉 6s over DWI volume 〉 1.2, difference between Tmax 〉 6s and DWI volume 〉 10ml, and DWI volume 〈 100ml. The aim of this study was to compare the required sample size of acute stroke studies that use MRI selection to that of studies which do not use MRI selection. Methods: All sample size calculations were based on an alpha of 0.05 in a two-sided test and a desired power of 0.8. MRI patient selection was assumed to be according to Target Mismatch criteria. The primary study outcome was assumed to be good functional outcome, defined as a modified Rankin Scale of 0-2 at 90 days. Other assumptions for the sample size calculations were based on data from the literature and data from the pooled EPITHET-DEFUSE database regarding patients with middle cerebral artery (MCA) occlusions treated up to six hours after symptom onset. The spontaneous reperfusion rate in this population was assumed to be 0.22. For MRI-selected mismatch patients the rate of good functional outcome was assumed to be 0.73 with reperfusion and 0.30 without reperfusion. For unselected patients, the rate of favorable clinical outcome was assumed to be 0.67 with reperfusion and 0.41 without reperfusion. Results: A trial of an intervention that leads to reperfusion of the MCA in 45% of patients would require 396 patients per group if MRI selection criteria were applied and 1096 patients per group without MRI selection criteria. A trial of an intervention that has a 70% reperfusion rate would require 92 patients in each arm if MRI selection criteria were applied versus 251 patients per arm if patients were enrolled without MRI selection. (see figure ) Conclusion: MRI selection can markedly reduce the required sample size of randomized controlled stroke trials in the delayed time-window. This advantage needs to be balanced against the potential drawbacks of using a MRI-marker as an inclusion criterion for a randomized controlled trial.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/str.43.suppl_1.A92
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2012
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  • 5
    Online Resource
    Online Resource
    Abstract 133: Magnetic Resonance Imaging Based Transient Ischemic Attack Triage In The Emergency Department Is Feasible And Safe
    Ovid Technologies (Wolters Kluwer Health) ; 2013
    In:  Stroke Vol. 44, No. suppl_1 ( 2013-02)
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 44, No. suppl_1 ( 2013-02)
    Abstract: Objective: To evaluate the safety and feasibility of a magnetic resonance imaging (MRI) based transient ischemic attack (TIA) triage pathway in the emergency department (ED). We hypothesized that an MRI based triage pathway in an academic setting would be feasible and associated with a low rate of stroke recurrence. Methods: From January 2010 to May 2011, consecutive patients assessed in our institution’s ED for suspicion of TIA were evaluated by a neurologist and underwent MRI with diffusion weighted imaging (DWI) and MRA of the head and neck within 12 hours per radiology department convention. By protocol, the neurologist recommended admission for patients with restricted diffusion on MRI, symptomatic vessel stenosis, or per clinical judgment. Final diagnosis was adjudicated by the treating neurologist at the time of discharge as definite or possible transient cerebrovascular event, or a non-cerebrovascular event. Stroke recurrence was evaluated at 1 week, 3 months, and 1 year with a telephone interview. Results: One hundred and twenty nine patients were enrolled with a mean age of 69 years (+/-16.8) and median ABCD 2 of 3 (IQR 3-4). Final diagnosis was definite transient cerebrovascular event in 77 (59.7%), possible in 21 (16.3%), and other in 31 (24%). At the time of triage, 112 (92%) patients underwent brain MRI in the ED after a median delay of 8.2 hours (IQR 4.8-14.7) from arrival and 15.7 hours (IQR 9.9-22.8) from symptom onset. No patients experienced a recurrent stroke before imaging. Twenty two (19.6%) patients had a positive DWI and 9 (8%) had a symptomatic vessel stenosis. All but two patients with a positive DWI or MRA were admitted. In total, 46 of the 129 (35.7%) patients were hospitalized and one (2.2%) had a recurrent stroke after 90 days. Of 83 patients discharged from the ED, one (1.2%) had a minor stroke at one week. This patient’s baseline MRI was DWI negative and MRA was without stenosis. Altogether, among 98 patients with a final diagnosis of possible or definite transient cerebrovascular event, the rate of recurrent stroke was 1.03% at 7 and 90 days, and 2.2% at one year. Conclusion: Acute evaluation of TIA using an MRI based triage approach is feasible and associated with a low rate of recurrent stroke.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/str.44.suppl_1.A133
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2013
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  • 6
    Online Resource
    Online Resource
    Abstract 3071: Automated CT Perfusion Processing For the Evaluation of Transient Ischemic Attack
    Ovid Technologies (Wolters Kluwer Health) ; 2012
    In:  Stroke Vol. 43, No. suppl_1 ( 2012-02)
    Details
    In: Stroke, Ovid Technologies (Wolters Kluwer Health), Vol. 43, No. suppl_1 ( 2012-02)
    Abstract: Introduction: The diagnosis of transient ischemic attack (TIA) can be difficult. We evaluated the yield of automated CT perfusion (CTP) in addition to non contrast head CT and CT angiography for the detection of acute ischemic lesions among TIA patients and compare it with multimodal MRI [diffusion weighted imaging (DWI) and perfusion weighted imaging (PWI)] results. Methods: Consecutive patients with a final diagnosis of transient neurological symptoms secondary to ischemia who underwent acute CT, CTP and CTA were enrolled. A subset of the patients underwent multimodal MRI. Presence of symptomatic stenosis was assessed on CTA by the treating team at the time of patient evaluation. The presence and location of acute ischemic lesions was assessed on: CT, CTP, DWI, and PWI. The rater was blinded to the clinical presentation. The presence of a MR or CT perfusion lesion was assessed using TMax. TMax maps for both CT and MR were automatically generated by RApid processing of PerfusIon and Diffusion (RAPID) software. Results: Thirty-three patients were enrolled: median age was 66 years old (IQR 58-82); median ABCD2 score was 4 (IQR 3-5); median delay from symptom onset to CTP was 4.6 hours (IQR 2-9.6). MRI was performed in 23 (70%) patients after a median delay of 20.4 hours (IQR 8.3-30.6) after symptom onset and 5.5 hours (IQR 3.4-20.8) after CTP. No patient experienced recurrence between CTP and MRI. Non-contrast head CT did not demonstrate any acute ischemic lesions. CTA found 3 symptomatic vessel lesions. CTP revealed a focal ischemic lesion in 11 patients (33%). The lesion location concurred with the presumed symptom side in all but one patient, and with the 3 symptomatic vessel lesions found on CTA. DWI was performed in 23 patients, and was positive in 7 (30%). Three of these patients had a negative early CTP. CTP was positive in 3 patients with subsequent normal DWI. MR perfusion was performed in 17 patients and found an acute ischemic lesion in 8 (47%) of them. Four of these MR PWI positive patients also had a positive CTP. In 3 patients with a negative MR PWI, CTP detected an acute ischemic lesion. At least 1 of the 3 modalities (CTP, DWI, PWI) was positive among 10/17 (59%) of patients. Conclusion: The results of this exploratory study suggest that automatically processed CTP increases the yield of head CT and CTA for the evaluation of TIA patients. In some cases CTP found evidence of transient focal ischemia that was not detected by MRI, in others CTP was negative and DWI or PWI was positive. These findings suggest that CTP and MRI may be complementary techniques to confirm the ischemic nature of transient neurological symptoms.
    Type of Medium: Online Resource
    ISSN: 0039-2499 , 1524-4628
    URL: Article
    DOI: 10.1161/str.43.suppl_1.A3071
    RVK:
    XA 10000
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2012
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  • 7
    Online Resource
    Online Resource
    Diffusion–perfusion MRI for triaging transient ischemic attack and acute cerebrovascular syndromes
    Ovid Technologies (Wolters Kluwer Health) ; 2011
    In:  Current Opinion in Neurology Vol. 24, No. 1 ( 2011-02), p. 44-49
    Details
    In: Current Opinion in Neurology, Ovid Technologies (Wolters Kluwer Health), Vol. 24, No. 1 ( 2011-02), p. 44-49
    Type of Medium: Online Resource
    ISSN: 1350-7540
    URL: Article
    DOI: 10.1097/WCO.0b013e328341f8a5
    Language: English
    Publisher: Ovid Technologies (Wolters Kluwer Health)
    Publication Date: 2011
    detail.hit.zdb_id: 2026967-5
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