CTA Protocols in a Telestroke Network Improve Efficiency for Both Spoke and Hub Hospitals.

BACKGROUND AND PURPOSE: Telestroke networks support screening for patients with emergent large-vessel occlusions who are eligible for endovascular thrombectomy. Ideal triage processes within telestroke networks remain uncertain. We characterize the impact of implementing a routine spoke hospital CTA protocol in our integrated telestroke network on transfer and thrombectomy patterns. MATERIALS AND METHODS: A protocol-driven CTA process was introduced at 22 spoke hospitals in November 2017. We retrospectively identified prospectively collected patients who presented to a spoke hospital with National Institutes of Health Stroke Scale scores ≥6 between March 1, 2016 and March 1, 2017 (pre-CTA), and March 1, 2018 and March 1, 2019 (post-CTA). We describe the demographics, CTA utilization, spoke hospital retention rates, emergent large-vessel occlusion identification, and rates of endovascular thrombectomy. RESULTS: There were 167 patients pre-CTA and 207 post-CTA. The rate of CTA at spoke hospitals increased from 15% to 70% (P < .001). Despite increased endovascular thrombectomy screening in the extended window, the overall rates of transfer out of spoke hospitals remained similar (56% versus 54%; P = .83). There was a nonsignificant increase in transfers to our hub hospital for endovascular thrombectomy (26% versus 35%; P = .12), but patients transferred >4.5 hours from last known well increased nearly 5-fold (7% versus 34%; P < .001). The rate of endovascular thrombectomy performed on patients transferred for possible endovascular thrombectomy more than doubled (22% versus 47%; P = .011). CONCLUSIONS: Implementation of CTA at spoke hospitals in our telestroke network was feasible and improved the efficiency of stroke triage. Rates of patients retained at spoke hospitals remained stable despite higher numbers of patients screened. Emergent large-vessel occlusion confirmation at the spoke hospital lead to a more than 2-fold increase in thrombectomy rates among transferred patients at the hub.

Telestroke-the promise and the challenge. Part one: growth and current practice.

Acute ischemic stroke remains a major public health concern, with low national treatment rates for the condition, demonstrating a disconnection between the evidence of treatment benefit and delivery of this treatment. Intravenous thrombolysis and endovascular thrombectomy are both strongly evidence supported and exquisitely time sensitive therapies. The mismatch between the distribution and incidence of stroke presentations and the availability of specialist care significantly affects access to care. Telestroke, the use of telemedicine for stroke, aims to surmount this hurdle by distributing stroke expertise more effectively, through video consultation with and examination of patients in locations removed from specialist care. This is the first of a detailed two part review, and explores the growth and current practice of telestroke, including the specific role it plays in the assessment and management of patients after emergent large vessel occlusion.

Telestroke-the promise and the challenge. Part two-expansion and horizons.

Acute ischemic stroke remains a major public health concern, with low national treatment rates for the condition, demonstrating a disconnection between the evidence of treatment benefit and delivery of this treatment. Intravenous thrombolysis and endovascular thrombectomy are both strongly evidence supported and exquisitely time sensitive therapies. The mismatch between the distribution and incidence of stroke presentations and the availability of specialist care significantly affects access to care. Telestroke, the use of telemedicine for stroke, aims to surmount this hurdle by distributing stroke expertise more effectively, through video consultation with and examination of patients in locations removed from specialist care. This is the second of a two part review, and is focused on the challenges telestroke faces for wider adoption. It further details the anticipated evolution of this novel therapeutic platform, and the potential roles it holds in stroke prevention, ambulance based care, rehabilitation, and research.

Combining MRI with NIHSS thresholds to predict outcome in acute ischemic stroke: value for patient selection.

BACKGROUND AND PURPOSE: Selecting acute ischemic stroke patients for reperfusion therapy on the basis of a diffusion-perfusion mismatch has not been uniformly proved to predict a beneficial treatment response. In a prior study, we have shown that combining clinical with MR imaging thresholds can predict clinical outcome with high positive predictive value. In this study, we sought to validate this predictive model in a larger patient cohort and evaluate the effects of reperfusion therapy and stroke side. MATERIALS AND METHODS: One hundred twenty-three consecutive patients with anterior circulation acute ischemic stroke underwent MR imaging within 6 hours of stroke onset. DWI and PWI volumes were measured. Lesion volume and NIHSS score thresholds were used in models predicting good 3-month clinical outcome (mRS 0-2). Patients were stratified by treatment and stroke side. RESULTS: Receiver operating characteristic analysis demonstrated 95.6% and 100% specificity for DWI > 70 mL and NIHSS score > 20 to predict poor outcome, and 92.7% and 91.3% specificity for PWI (mean transit time) < 50 mL and NIHSS score < 8 to predict good outcome. Combining clinical and imaging thresholds led to an 88.8% (71/80) positive predictive value with a 65.0% (80/123) prognostic yield. One hundred percent specific thresholds for DWI (103 versus 31 mL) and NIHSS score (20 versus 17) to predict poor outcome were significantly higher in treated (intravenous and/or intra-arterial) versus untreated patients. Prognostic yield was lower in right- versus left-sided strokes for all thresholds (10.4%-20.7% versus 16.9%-40.0%). Patients with right-sided strokes had higher 100% specific DWI (103.1 versus 74.8 mL) thresholds for poor outcome, and the positive predictive value was lower. CONCLUSIONS: Our predictive model is validated in a much larger patient cohort. Outcome may be predicted in up to two-thirds of patients, and thresholds are affected by stroke side and reperfusion therapy.

Exposing hidden truncation-related errors in acute stroke perfusion imaging.

BACKGROUND AND PURPOSE: The durations of acute ischemic stroke patients' CT or MR perfusion scans may be too short to fully sample the passage of the injected contrast agent through the brain. We tested the potential magnitude of hidden errors related to the truncation of data by short perfusion scans. MATERIALS AND METHODS: Fifty-seven patients with acute ischemic stroke underwent perfusion MR imaging within 12 hours of symptom onset, using a relatively long scan duration (110 seconds). Shorter scan durations (39.5-108.5 seconds) were simulated by progressively deleting the last-acquired images. CBV, CBF, MTT, and time to response function maximum (Tmax) were measured within DWI-identified acute infarcts, with commonly used postprocessing algorithms. All measurements except Tmax were normalized by dividing by the contralateral hemisphere values. The effects of the scan duration on these hemodynamic measurements and on the volumes of lesions with Tmax of >6 seconds were tested using regression. RESULTS: Decreasing scan duration from 110 seconds to 40 seconds falsely reduced perfusion estimates by 47.6%-64.2% of normal for CBV, 1.96%-4.10% for CBF, 133%-205% for MTT, and 6.2-8.0 seconds for Tmax, depending on the postprocessing method. This truncation falsely reduced estimated Tmax lesion volume by 71.5 or 93.8 mL, depending on the deconvolution method. "Lesion reversal" (ie, change from above-normal to apparently normal, or from >6 seconds to ≤6 seconds for the time to response function maximum) with increasing truncation occurred in 37%-46% of lesions for CBV, 2%-4% for CBF, 28%-54% for MTT, and 42%-44% for Tmax, depending on the postprocessing method. CONCLUSIONS: Hidden truncation-related errors in perfusion images may be large enough to alter patient management or affect outcomes of clinical trials.

Outcomes of intravenous tissue plasminogen activator for acute ischaemic stroke in HIV-infected adults.

BACKGROUND AND PURPOSE: To our knowledge there are no studies reporting the use and short-term outcomes of intravenous tissue plasminogen activator (IV-TPA) for the treatment of acute ischaemic stroke (AIS) in people living with HIV. METHODS: The US Nationwide Inpatient Sample (NIS) (2006-2010) was searched for HIV-infected AIS patients treated with IV-TPA. RESULTS: In the NIS, 2.2% (62/2877) of HIV-infected AIS cases were thrombolyzed with IV-TPA (median age 52 years, range 27-78, 32% female, 22% Caucasian) vs. 2.1% (19 335/937 896) of HIV-uninfected cases (median age 72 years, range 17-102 years, 50% female, 74% Caucasian; P = 0.77). There were more deaths in HIV-infected versus uninfected patients with stroke (220/2877, 7.6% vs. 49 089/937 547, 5.2%, P < 0.001) but no difference in the proportion of deaths amongst IV-TPA-treated patients. The age- and sex-adjusted odds ratio for death following IV-TPA administration in HIV-infected versus uninfected patients was 2.26 (95% CI 1.12, 4.58), but the interaction on mortality between HIV and IV-TPA use was not statistically significant, indicating no difference in risk of in-hospital death by HIV serostatus with IV-TPA use. A higher number of HIV-infected patients remained in hospital versus died or were discharged at both 10 and 30 days (P < 0.01 at 10 and 30 days). No difference in the proportion of intracerebral hemorrhage in the two groups was found (P = 0.362). CONCLUSIONS: The in-hospital mortality is higher amongst HIV-infected AIS patients than HIV-uninfected patients. However, the risk of death amongst HIV-infected patients treated with IV-TPA is similar to HIV-uninfected groups.

A score to predict early risk of recurrence after ischemic stroke.

BACKGROUND: There is currently no instrument to stratify patients presenting with ischemic stroke according to early risk of recurrent stroke. We sought to develop a comprehensive prognostic score to predict 90-day risk of recurrent stroke. METHODS: We analyzed data on 1,458 consecutive ischemic stroke patients using a Cox regression model with time to recurrent stroke as the response and clinical and imaging features typically available to physician at admission as covariates. The 90-day risk of recurrent stroke was calculated by summing up the number of independent predictors weighted by their corresponding beta-coefficients. The resultant score was called recurrence risk estimator at 90 days or RRE-90 score (available at: http://www.nmr.mgh.harvard.edu/RRE-90/). RESULTS: Sixty recurrent strokes (54 had baseline imaging) occurred during the follow-up period. The risk adjusted for time to follow-up was 6.0%. Predictors of recurrence included admission etiologic stroke subtype, prior history of TIA/stroke, and topography, age, and distribution of brain infarcts. The RRE-90 score demonstrated adequate calibration and good discrimination (area under the ROC curve [AUC] = 0.70-0.80), which was maintained when applied to a separate cohort of 433 patients (AUC = 0.70-0.76). The model's performance was also maintained for predicting early (14-day) risk of recurrence (AUC = 0.80). CONCLUSIONS: The RRE-90 is a Web-based, easy-to-use prognostic score that integrates clinical and imaging information available in the acute setting to quantify early risk of recurrent stroke. The RRE-90 demonstrates good predictive performance, suggesting that, if validated externally, it has promise for use in creating individualized patient management algorithms and improving clinical practice in acute stroke care.

Unsuspected coagulopathy rarely prevents IV thrombolysis in acute ischemic stroke.

BACKGROUND: American Heart Association/American Stroke Association guidelines recommend initiating treatment with IV tissue plasminogen activator (tPA) in acute ischemic stroke patients without suspected coagulopathy prior to availability of clotting results; however, little or no data support this practice. We sought to identify how often blood clotting abnormalities were responsible for withholding IV tPA at our institution. METHODS: We conducted a retrospective review of our prospectively acquired Get With the Guidelines Stroke database from January 2003 to April 2008. All patients underwent clinical evaluation by a neurologist, diagnostic neuroimaging, and laboratory testing on admission. We classified patients with absolute contraindications to IV tPA as ineligible, and those with warnings/relative contraindications or potentially treatable factors as potentially eligible. RESULTS: Of 2,335 considered for analysis, 470 (20.1%) patients presented to our emergency department (ED) within 3 hours. Among these, 147 (31.3%) received IV tPA in our ED, 102 (21.7%) had an absolute contraindication, and 221 (47%) had a reason to consider withholding tPA. Only 30/470 (6.4%) of potential thrombolysis patients were discovered to have international normalized ratio > or =1.7 or platelets < or =100,000/microL, and of these, 28 were suspected a priori due to known coagulopathy from medication or illness. Only 2/470 (0.4%) patients had an unsuspected coagulopathy that ultimately prevented thrombolysis. CONCLUSIONS: Based on the experience of a large thrombolysis referral center, stroke patients without suspected clotting abnormality can safely begin thrombolytic therapy before clotting results are available. These data support the current practice guidelines, and may reassure clinicians that the benefits of early administration greatly outweigh the risks due to an unsuspected bleeding diathesis.

Influence of stroke subtype on quality of care in the Get With The Guidelines-Stroke Program.

OBJECTIVE: Little is known about in-hospital care for hemorrhagic stroke. We examined quality of care in intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH) admissions in the national Get With The Guidelines-Stroke (GWTG-Stroke) database, and compared them to ischemic stroke (IS) or TIA admissions. METHODS: Between April 1, 2003, and December 30, 2007, 905 hospitals contributed 479,284 consecutive stroke and TIA admissions. The proportions receiving each quality of care measure were calculated by dividing the total number of patients receiving the intervention by the total number of patients eligible for the intervention, excluding ineligible patients or those with contraindications to treatment. Logistic regression models were used to determine associations between measure compliance and stroke subtype, controlling for patient and hospital characteristics. RESULTS: Stroke subtypes were 61.7% IS, 23.8% TIA, 11.1% ICH, and 3.5% SAH. Performance on care measures was generally lower in ICH and SAH compared to IS/TIA, including guideline-recommended measures for deep venous thrombosis (DVT) prevention (for ICH) and smoking cessation (for SAH) (multivariable-adjusted p < 0.001 for all comparisons). Exceptions were that ICH patients were more likely than IS/TIA to have door-to-CT times <25 minutes (multivariable-adjusted p < 0.001) and to undergo dysphagia screening (multivariable-adjusted p < 0.001). Time spent in the GWTG-Stroke program was associated with improvements in many measures of care for ICH and SAH patients, including DVT prevention and smoking cessation therapy (multivariable-adjusted p < 0.001). CONCLUSIONS: Many hospital-based acute care and prevention measures are underutilized in intracerebral hemorrhage and subarachnoid hemorrhage compared to ischemic stroke /TIA. Duration of Get With The Guidelines-Stroke participation is associated with improving quality of care for hemorrhagic stroke.

Feasibility of NIRS in the neurointensive care unit: a pilot study in stroke using physiological oscillations.

INTRODUCTION: Near-infrared spectroscopy (NIRS) is a non-invasive, real-time bedside modality sensitive to changes in cerebral perfusion and oxygenation and is highly sensitive to physiological oscillations at different frequencies. However, the clinical feasibility of NIRS remains limited, partly due to concerns regarding NIRS signal quantification, which relies on mostly arbitrary assumptions on hemoglobin concentrations and tissue layers. In this pilot study comparing stroke patients to healthy controls, we explored the utility of the interhemispheric correlation coefficient (IHCC) during physiological oscillations in detecting asymmetry in hemispheric microvascular hemodynamics. METHODS: Using bi-hemispheric continuous-wave NIRS, 12 patients with hemispheric strokes and 9 controls were measured prospectively. NIRS signal was band-pass filtered to isolate cardiac (0.7-3 Hz) and respiratory (0.15-0.7 Hz) oscillations. IHCCs were calculated in both oscillation frequency bands. Using Fisher's Z-transform for non-Gaussian distributions, the IHCC during cardiac and respiratory oscillations were compared between both groups. RESULTS: Nine patients and nine controls had data of sufficient quality to be included in the analysis. The IHCCs during cardiac and respiratory oscillations were significantly different between patients versus controls (cardiac 0.79 +/- 0.18 vs. 0.94 +/- 0.07, P = 0.025; respiratory 0.24 +/- 0.28 vs. 0.59 +/- 0.3; P = 0.016). CONCLUSIONS: Computing the IHCC during physiological cardiac and respiratory oscillations may be a new NIRS analysis technique to quantify asymmetric microvascular hemodynamics in stroke patients in the neurocritical care unit. It allows each subject to serve as their own control obviating the need for arbitrary assumptions on absolute hemoglobin concentration. Future clinical applications may include rapid identification of patients with ischemic brain injury in the pre-hospital setting. This promising new analysis technique warrants further validation.

ABC/2 for rapid clinical estimate of infarct, perfusion, and mismatch volumes.

BACKGROUND: Rapid and easy clinical assessments for volumes of infarction and perfusion mismatch are needed. We tested whether simple geometric models generated accurate estimates of these volumes. METHODS: Acute diffusion-weighted image (DWI) and perfusion (mean transit time [MTT]) in 63 strokes and established infarct volumes in 50 subacute strokes were measured by computerized planimetry. Mismatch was defined as MTT/DWI > or = 1.2. Observers, blinded to planimetric values, measured lesions in three perpendicular axes A, B, and C. Geometric estimates of sphere, ellipsoid, bicone, and cylinder were compared to planimetric volume by least-squares linear regression. RESULTS: The ABC/2 formula (ellipsoid) was superior to other geometries for estimating volume of DWI (slope 1.16, 95% confidence interval [CI] 0.94 to 1.38; R(2) = 0.91, p = 0.001) and MTT (slope 1.11, 95% CI 0.99 to 1.23; R(2) = 0.89, p = 0.001). The intrarater and interrater reliability for ABC/2 was high for both DWI (0.992 and 0.965) and MTT (0.881 and 0.712). For subacute infarct, the ABC/2 formula also best estimated planimetric volume (slope 1.00, 95% CI 0.98 to 1.19; R(2) = 0.74, p = 0.001). In general, sphere and cylinder geometries overestimated all volumes and bicone underestimated all volumes. The positive predictive value for mismatch was 92% and negative predictive value was 33%. CONCLUSIONS: Of the models tested, ABC/2 is reproducible, is accurate, and provides the best simple geometric estimate of infarction and mean transit time volumes. ABC/2 has a high positive predictive value for identifying mismatch greater than 20% and might be a useful tool for rapid determination of acute stroke treatment.

Endovascular approaches to acute stroke, part 1: Drugs, devices, and data.

Despite years of research and pioneering clinical work, stroke remains a massive public health concern. Since 1996, we have lived in the era of US Food and Drug Administration-approved intravenous (i.v.) recombinant tissue plasminogen activator (rtPA). This treatment, despite its promise, continues to exhibit its limitations. Endovascular therapy has several theoretic advantages over i.v. rtPA, including site specificity, longer treatment windows, and higher recanalization rates. In this article, we will review the various pharmacologic strategies for acute stroke treatment, providing both a historic context and the state of the art. The drugs will be classified on the basis of their theoretic rationale for therapy. Next, we will review the various devices and strategies for mechanical revascularization with an aim toward comprehensiveness. These range from wire disruption of thrombus to preclinical trials for novel mechanical solutions. This first installment of this 2-part series will end with an analysis of retrograde reperfusion techniques.

Case volumes of intra-arterial and intravenous treatment of ischemic stroke in the USA.

BACKGROUND AND PURPOSE: Ischemic stroke is a major cause of disability and death in the USA. Intravenous tissue plasminogen activator (t-PA) remains underutilized. With the development of newer intra-arterial reperfusion therapies, there is increased opportunity to address the more devastating large-vessel occlusions. We seek to identify the numbers of patients with stroke treated with intravenous and intra-arterial therapies, as well as to estimate the potential number of intra-arterial cases in the foreseeable future. METHODS: We performed a literature search to determine case volumes of intravenous t-PA use. We extrapolated the current case volume of intra-arterial stroke therapies from the numbers of cases in which the Merci retrieval device was used. In order to estimate the potential numbers of intra-arterial stroke cases, we characterized the percentage of patients with stroke who received intra-arterial therapy at two leading stroke centers. We applied these percentages to the numbers of patients with stroke seen at the top 100, 200 and 500 stroke centers by volume. RESULTS: The rate of intravenous t-PA use is 2.4-3.6%, resulting in 15 000-22 000 cases/year in the USA. The estimated case volume of intra-arterial therapies is 3500-7200 in 2006. Based on data from St. Luke's Brain and Stroke Institute and Massachusetts General Hospital, approximately 5-20% of patients with ischemic stroke can be treated with intra-arterial therapies. Extrapolating this to the top 500 stroke centers by volume, the potential number of intra-arterial cases in the USA is 10 400-41 500/year. CONCLUSION: Based on the current numbers of intra-arterial cases, our theoretical model identifies a potential for significant growth of this stroke therapy.

Role of recanalization in acute stroke outcome: rationale for a CT angiogram-based "benefit of recanalization" model.

BACKGROUND AND PURPOSE: In acute middle cerebral artery (MCA) stroke, CT angiographic (CTA) source images (CTA-SI) identify tissue likely to infarct despite early recanalization. This pilot study evaluated the impact of recanalization status on clinical and radiologic predictors of patient outcomes. MATERIALS AND METHODS: Of 44 patients undergoing CT/CTA within 6 hours of developing symptoms of proximal MCA ischemia, 19 patients achieved complete proximal MCA (MCA M1) recanalization. Admission National Institutes of Health Stroke Scale (NIHSS) score, onset-to-imaging time, CTA-SI Alberta Stroke Program Early CT Score, MCA M1 occlusion, cerebrovascular collaterals score, and CTA-SI lesion volume were correlated with 3- to 6-month follow-up modified Rankin Scale (mRS). We developed 2 stepwise regression models: one for patients with complete MCA M1 recanalization and one for patients without complete recanalization. RESULTS: Complete and incomplete recanalization groups had similar median admission NIHSS scores (19 versus 19) and mean onset-to-imaging times (2.3 versus 1.9 hours) but different proportions of patients achieving mRS scores 0-2 (74% versus 40%; P = .04). The only independent predictors of clinical outcome in patients with complete recanalization were onset-to-imaging time and admission CTA-SI lesion volume (total model R(2) = 0.75; P = .01). The only independent predictors of outcome in patients with incomplete recanalization were admission CTA-SI lesion volume and NIHSS score (total model R(2) = 0.66; P = .007). CONCLUSION: Regardless of recanalization status, admission CTA-SI lesion volume was associated with clinical outcome. Recanalization status did, however, affect which variables in addition to CTA-SI volume significantly impacted clinical outcome: time with complete recanalization and NIHSS with incomplete recanalization. This finding may support the development of a model predicting the potential clinical benefit expected with early successful recanalization.

An acute ischemic stroke classification instrument that includes CT or MR angiography: the Boston Acute Stroke Imaging Scale.

BACKGROUND AND PURPOSE: A simple classification instrument based on imaging that predicts outcomes in patients with acute ischemic stroke is lacking. We tested the hypotheses that the Boston Acute Stroke Imaging Scale (BASIS) classification instrument effectively predicts patient outcomes and is superior to the Alberta Stroke Program Early CT Score (ASPECTS) in predicting outcomes in acute ischemic stroke. MATERIALS AND METHODS: Of 230 prospectively screened, consecutive patients with acute ischemic stroke, 87 had noncontrast CT (NCCT)/CT angiography (CTA), and 118 had MR imaging/MR angiography (MRA) at admission and were classified as having major stroke by BASIS criteria if they had a proximal cerebral artery occlusion or, if no occlusion, imaging evidence of significant parenchymal ischemia; all of the others were classified as minor strokes. Outcomes included death, length of hospitalization, and discharge disposition. BASIS was compared with ASPECTS (dichotomized > or

Neuroanatomic correlates of stroke-related myocardial injury.

BACKGROUND: Myocardial injury can occur after ischemic stroke in the absence of primary cardiac causes. The neuroanatomic basis of stroke-related myocardial injury is not well understood. OBJECTIVE: To identify regions of brain infarction associated with myocardial injury using a method free of the bias of an a priori hypothesis as to any specific location. METHODS: Of 738 consecutive patients with acute ischemic stroke, the authors identified 50 patients in whom serum cardiac troponin T (cTnT) elevation occurred in the absence of any apparent cause within 3 days of symptom onset. Fifty randomly selected, age- and sex-matched patients with ischemic stroke without cTnT elevation served as controls. Diffusion-weighted images with outlines of infarction were co-registered to a template, averaged, and then subtracted to find voxels that differed between the two groups. Voxel-wise p values were determined using a nonparametric permutation test to identify specific regions of infarction that were associated with cTnT elevation. RESULTS: The study groups were well balanced with respect to stroke risk factors, history of coronary artery disease, infarction volume, and frequency of right and left middle cerebral artery territory involvement. Brain regions that were a priori associated with cTnT elevation included the right posterior, superior, and medial insula and the right inferior parietal lobule. Among patients with right middle cerebral artery infarction, the insular cluster was involved in 88% of patients with and 33% without cTnT elevation (odds ratio: 15.00; 95% CI: 2.65 to 84.79). CONCLUSIONS: Infarctions in specific brain regions including the right insula are associated with elevated serum cardiac troponin T level indicative of myocardial injury.

Thrombolytic therapy of acute ischemic stroke during pregnancy.

The authors report eight pregnant women with acute ischemic stroke treated with thrombolysis (rt-PA [recombinant human tissue plasminogen activator] or urokinase). Seven women recovered. Two extracranial and two asymptomatic intracranial hemorrhages complicated treatment; one woman died of arterial dissection complicating angiography. Three patients had therapeutic abortions, two fetuses were miscarried, and two babies were delivered healthy. Although pregnant women may be treated safely with thrombolytics, risks and benefits to mother and fetus must be carefully weighed.

First-pass quantitative CT perfusion identifies thresholds for salvageable penumbra in acute stroke patients treated with intra-arterial therapy.

BACKGROUND AND PURPOSE: The purpose of this study was to determine whether, in acute stroke patients treated with intra-arterial (IA) recanalization therapy, CT perfusion (CTP) can distinguish ischemic brain tissue destined to infarct from that which will survive. METHODS: Dynamic CTP was obtained in 14 patients within 8 hours of stroke onset, before IA therapy. Initial quantitative cerebral blood volume (CBV) and flow (CBF) values were visually segmented and normalized in the "infarct core" (region 1: reduced CBV and CBF, infarction on follow-up), "penumbra that infarcts" (region 2: normal CBV, reduced CBF, infarction on follow-up), and "penumbra that recovers" (region 3: normal CBV, reduced CBF, normal on follow-up). Normalization was accomplished by dividing the ischemic region of interest value by that of a corresponding, contralateral, uninvolved region, which resulted in CBV and CBF "ratios." Separate CBV and CBF values were obtained in gray matter (GM) and white matter (WM). RESULTS: Mean CBF ratios for regions 1, 2, and 3 were 0.19 +/- 0.06, 0.34 +/- 0.06, and 0.46 +/- 0.09, respectively (all P < .001). Mean CBV ratios for regions 1, 2, and 3 were similarly distinct (all P < .05). Absolute CBV and CBF values for regions 2 and 3 were not significantly different. All regions with CBF ratio <0.32, CBV ratio <0.68, CBF <12.7 mL/100 g/min, or CBV <2.2 mL/100 g infarcted. No region with CBF ratio >0.44 infarcted. GM versus WM CBF and CBV values were significantly different for region 2 compared with region 3 (P < .05). CONCLUSIONS: In acute stroke patients, quantitative CTP can distinguish ischemic tissue likely to infarct from that likely to survive.