Recommendations for imaging of acute ischemic stroke: a scientific statement from the American Heart Association

Imaging-based treatment selection for intravenous and intra-arterial stroke therapies: a comprehensive review

Reperfusion therapy is the only approved treatment for acute ischemic stroke. The current approach to patient selection is primarily based on the time from stroke symptom onset. However, this algorithm sharply restricts the eligible patient population, and neglects large variations in collateral circulation that ultimately determine the therapeutic time window in individual patients. Time alone is unlikely to remain the dominant parameter. Alternative approaches to patient selection involve advanced neuroimaging methods including MRI diffusion-weighted imaging, magnetic resonance and computed tomography perfusion imaging and noninvasive angiography that provide potentially valuable information regarding the state of the brain parenchyma and the neurovasculature. These techniques have now been used extensively, and there is emerging evidence on how specific imaging data may result in improved clinical outcomes. This article will review the major studies that have investigated the role of imaging in patient selection for both intravenous and intra-arterial therapies.

A new image-based stroke registry containing quantitative magnetic resonance imaging data

BACKGROUND

Conventional stroke registries contain alphanumeric text-based data on the clinical status of stroke patients, but this format captures imaging data in a very limited form. There is a need for a new type of stroke registry to capture both text- and image-based data.

METHODS AND RESULTS

We designed a next-generation stroke registry containing quantitative magnetic resonance imaging (MRI) data, 'DUIH_SRegI', developed a supporting software package, 'Image_QNA', and performed experiments to assess the feasibility and utility of the system. Image_QNA enabled the mapping of stroke-related lesions on MR onto a standard brain template and the storage of this extracted imaging data in a visual database. Interuser and intrauser variability of the lesion mapping procedure was low. We compared the results from the semi automatic lesion registration using Image_QNA with automatic lesion registration using SPM5 (Statistical Parametric Mapping version 5), a well-regarded standard neuroscience software package, in terms of lesion location, size and shape, and found Image_QNA to be superior. We assessed the clinical usefulness of an image-based registry by studying 47 consecutive patients with first-ever lacunar infarcts in the corona radiata. We used the enriched dataset comprised of both image-based and alphanumeric databases to show that diffusion MR lesions overlapped in a more posterolateral brain location for patients with high NIH Stroke Scale scores (≥4) than for patients with low scores (≤3). In April 2009, we launched the first prospective image-based acute (≤1 week) stroke registry at our institution. The registered data include high signal intensity ischemic lesions on diffusion, T(2)-weighted, or fluid attenuation inversion recovery MRIs, and low signal intensity hemorrhagic lesions on gradient-echo MRIs. An interim analysis at 6 months showed that the time requirement for the lesion registration (183 consecutive patients, 3,226 MR slices with visible stroke-related lesions) was acceptable at about 1 h of labor per patient by a trained assistant with physician oversight.

CONCLUSIONS

We have developed a novel image-based stroke registry, with database functions that allow the formulation and testing of intuitive, image-based hypotheses in a manner not easily achievable with conventional alphanumeric stroke registries.

CT angiography predicts use of tertiary interventional services in acute ischemic stroke patients

Background

Patients with acute stroke are often transferred to tertiary care centers for advanced interventional services. We hypothesized that the presence of a proximal cerebral artery occlusion on CT angiography (CTA) is an independent predictor of the use of these services.

Methods

We performed a historical cohort study of consecutive ischemic stroke patients presenting within 24 h of symptom onset to an academic emergency department who underwent emergent CTA. Use of tertiary care interventions including intra-arterial (IA) thrombolysis, mechanical clot retrieval, and neurosurgery were captured.

Results

During the study period, 207/290 (71%) of patients with acute ischemic stroke underwent emergent CTA. Of the patients, 74/207 (36%) showed evidence of a proximal cerebral artery occlusion, and 22/207 (11%) underwent an interventional procedure. Those with proximal occlusions were more likely to receive a neurointervention (26% vs. 2%, p < 0.001). They were more likely to undergo IA thrombolysis (9% vs. 0%, p = 0.001) or a mechanical intervention (19% vs. 0%, p < 0.0001), but not more likely to undergo neurosurgery (5% vs. 2%, p = 0.2). After controlling for the initial NIH stroke scale (NIHSS) score, proximal occlusion remained an independent predictor of the use of neurointerventional services (OR 8.5, 95% CI 2.2-33). Evidence of proximal occlusion on CTA predicted use of neurointervention with sensitivity of 82% (95% CI 59-94%), specificity of 71% (95% CI 64%-77%), positive predictive value (PPV) of 25% (95% CI 16%-37%), and negative predictive value (NPV) of 97% (95% CI 92%-99%).

Conclusion

Proximal cerebral artery occlusion on CTA predicts the need for advanced neurointerventional services.

HOBOE (Head-of-Bed Optimization of Elevation) Study: association of higher angle with reduced cerebral blood flow velocity in acute ischemic stroke

BACKGROUND

Cerebral autoregulation can be impaired after ischemic stroke, with potential adverse effects on cerebral blood flow during early rehabilitation.

OBJECTIVE

The objective of this study was to assess changes in cerebral blood flow velocity with orthostatic variation at 24 hours after stroke.

DESIGN

This investigation was an observational study comparing mean flow velocities (MFVs) at 30, 15, and 0 degrees of elevation of the head of the bed (HOB).

METHODS

Eight participants underwent bilateral middle cerebral artery (MCA) transcranial Doppler monitoring during orthostatic variation at 24 hours after ischemic stroke. Computed tomography angiography separated participants into recanalized (artery completely reopened) and incompletely recanalized groups. Friedman tests were used to determine MFVs at the various HOB angles. Mann-Whitney U tests were used to compare the change in MFV (from 30° to 0°) between groups and between hemispheres within groups.

RESULTS

For stroke-affected MCAs in the incompletely recanalized group, MFVs differed at the various HOB angles (30°: median MFV=51.5 cm/s, interquartile range [IQR]=33.0 to 103.8; 15°: median MFV=55.5 cm/s, IQR=34.0 to 117.5; 0°: median MFV=85.0 cm/s, IQR=58.8 to 127.0); there were no significant differences for other MCAs. For stroke-affected MCAs in the incompletely recanalized group, MFVs increased with a change in the HOB angle from 30 degrees to 0 degrees by a median of 26.0 cm/s (IQR=21.3 to 35.3); there were no significant changes in the recanalized group (-3.5 cm/s, IQR=-12.3 to 0.8). The changes in MFV with a change in the HOB angle from 30 degrees to 0 degrees differed between hemispheres in the incompletely recanalized group but not in the recanalized group.

LIMITATIONS

Generalizability was limited by sample size.

CONCLUSIONS

The incompletely recanalized group showed changes in MFVs at various HOB angles, suggesting that cerebral blood flow in this group may be sensitive to orthostatic variation, whereas the recanalized group maintained stable blood flow velocities.

Clinical applications of diffusion MR imaging for acute ischemic stroke

Diffusion magnetic resonance imaging is the best imaging tool for detecting acute ischemic brain injury. Studies have shown its high accuracy for delineating irreversible tissue damage within the first few hours after stroke onset; however, the true value of any diagnostic tool is whether it can be used to guide clinical management. This review discusses the role of diffusion imaging in the evaluation of the patient with acute ischemic stroke, and how this role is influenced by other important stroke-related variables, including the level of vessel occlusion and the clinical deficit. The review focuses on decision-making for intravenous and intra-arterial reperfusion therapies.

Revised and updated recommendations for the establishment of primary stroke centers: a summary statement from the brain attack coalition

BACKGROUND AND PURPOSE

The formation and certification of Primary Stroke Centers has progressed rapidly since the Brain Attack Coalition's original recommendations in 2000. The purpose of this article is to revise and update our recommendations for Primary Stroke Centers to reflect the latest data and experience.

METHODS

We conducted a literature review using MEDLINE and PubMed from March 2000 to January 2011. The review focused on studies that were relevant for acute stroke diagnosis, treatment, and care. Original references as well as meta-analyses and other care guidelines were also reviewed and included if found to be valid and relevant. Levels of evidence were added to reflect current guideline development practices.

RESULTS

Based on the literature review and experience at Primary Stroke Centers, the importance of some elements has been further strengthened, and several new areas have been added. These include (1) the importance of acute stroke teams; (2) the importance of Stroke Units with telemetry monitoring; (3) performance of brain imaging with MRI and diffusion-weighted sequences; (4) assessment of cerebral vasculature with MR angiography or CT angiography; (5) cardiac imaging; (6) early initiation of rehabilitation therapies; and (7) certification by an independent body, including a site visit and disease performance measures.

CONCLUSIONS

Based on the evidence, several elements of Primary Stroke Centers are particularly important for improving the care of patients with an acute stroke. Additional elements focus on imaging of the brain, the cerebral vasculature, and the heart. These new elements may improve the care and outcomes for patients with stroke cared for at a Primary Stroke Center.

CT angiography source images acquired with a fast-acquisition protocol overestimate infarct core on diffusion weighted images in acute ischemic stroke

BACKGROUND AND PURPOSE

Studies have demonstrated that computed tomography (CT) angiography source images (CTA-SI) acquired under near-steady-state contrast concentration provide infarct core estimates equivalent to diffusion-weighted images (DWI). We sought to test this relationship using our current CTA protocol optimized for faster scan acquisition.

METHODS

Forty-eight consecutive acute ischemic stroke patients met the following criteria: fast-acquisition CTA and magnetic resonance imaging (MRI) within 9 hours of symptom onset, CTA-to-MRI interval under 2 hours, and anterior circulation vessel occlusion. Collaterals were graded on CTA, and lesion volumes were calculated on CTA-SI, DWI, and MR mean transit time (MTT) maps.

RESULTS

The mean CTA-to-MRI interval was 36 minutes (± 18 minutes). In paired analysis, lesion volumes on CTA-SI were significantly larger than on DWI (45.6 cm3 vs. 29.9 cm3; P < .0001). In 14 (29.2%) cases, there was major CTA-SI overestimation (>25 cm3 difference) of the DWI lesion. Lower collateral score (P = .001), higher National Institutes of Health stroke scale (NIHSS) score (P = .01), older age (P = .01), and proximal occlusion (P < .05) were univariate predictors of major overestimation, with collateral score being the only independent predictor. The interobserver agreement was worse for CTA-SI than for DWI (P < .001 for limits of agreement).

CONCLUSIONS

CTA-SI performed using a fast-acquisition protocol overestimates the infarct core on DWI. Substantial differences are observed in over 25% of cases, and are associated with reduced collateralization.

Vascular imaging in stroke: comparative analysis

Advances in stroke treatment have mirrored advances in vascular imaging. Understanding and advances in reperfusion therapies were made possible by improvements in computed tomographic angiography, magnetic resonance angiography, neurovascular ultrasound, and renewed interest in catheter angiography. As technology allows better noninvasive vascular diagnosis, digital subtraction angiography (the remaining gold standard for vascular imaging) is increasingly used for rescue procedures and elective interventions. This review will examine specific advantages and disadvantages of different vascular imaging modalities as related to stroke diagnosis.

Early management of stroke patients in the emergency department

Stroke continues to be one of the leading causes of death and adult disability. Increasing public awareness of stroke has led to a rise in the number of patients presenting to emergency departments (EDs) who qualify for emergent and time-sensitive treatments such as t-PA, clot extraction, and surgery. Timely treatment and supportive care of the stroke patient in the ED is crucial for patient outcomes. Emergency medicine (EM) pharmacists are the medication experts and can have a significant impact on the care of a stroke patient. Thus, it is essential for EM pharmacists to have a solid knowledge of the current guidelines and evidence-based literature or lack there of. In this article, we describe the epidemiology of stroke, review the classifications of stroke, and discuss the present treatment strategies for emergent and supportive care.

Intra-arterial stroke therapy: recanalization strategies, patient selection and imaging

With more than 700,000 strokes per year resulting in greater than 160,000 deaths per year, stroke remains the leading cause of disability and third leading cause of death in the United States. Despite an overall decline in stroke mortality over the past 40 years, the total number of stroke deaths continues to increase, suggesting an increase in stroke incidence. The last 20 years of neuroscience advances have moved stroke from a condition that is monitored clinically and imaged serially as it evolves to an entity that can be treated acutely, with remarkable alterations in its natural history.

CT Angiographic Source Images Predict Outcome and Final Infarct Volume Better Than Noncontrast CT in Proximal Vascular Occlusions

Background and Purpose—

Alberta Stroke Programme Early CT Score (ASPECTS) is widely used for assessment of early ischemic changes in acute stroke. We hypothesized that CT angiography source image (CTA-SI) ASPECTS correlates better with baseline National Institutes of Health Stroke Scale score, final ASPECTS and neurological outcomes when compared with noncontrast CT ASPECTS.

Methods—

We studied patients presenting with acute ischemic stroke and identified proximal arterial occlusions (internal carotid artery, middle cerebral artery M1, and proximal middle cerebral artery M2) from the Calgary CT Angiography database. CT scans were independently read by 3 observers for baseline noncontrast CT ASPECTS, CT angiography source image ASPECTS, and follow-up ASPECTS. Details of demographics and risk factors were noted. A modified Rankin Scale score ≤2 at 3 months was considered a favorable outcome.

Results—

We identified 261 patients with proximal occlusions for analysis. We found a better correlation between CT angiography source image ASPECTS and follow-up ASPECTS (Spearman correlation coefficient r =0.65; 95% CI, 0.58 to 0.72; P <0.001) than between noncontrast CT ASPECTS and follow-up CT ASPECTS ( r =0.46; 95% CI, 0.36 to 0.55; P <0.001). CT angiography source image ASPECTS correlated better with baseline National Institutes of Health Stroke Scale and 24-hour National Institutes of Health Stroke Scale when compared with noncontrast CT ASPECTS ( P <0.001). In an adjusted model including both CT angiography source image ASPECTS and noncontrast CT ASPECTS, CT angiography source image ASPECTS was associated with good outcome (OR, 2.30; 95%, CI, 1.16 to 4.53), whereas noncontrast CT ASPECTS was not (OR, 1.54; 95% CI, 0.84 to 2.82). Among imaging parameters, CT angiography source image ASPECTS was the only independent predictor of good outcome (OR, 2.29; 95% CI, 1.16 to 4.53).

Conclusions—

CT angiography source image ASPECTS correlates better with baseline stroke severity, is a better predictor of final infarct extension, and independently predicts neurological outcome than noncontrast CT ASPECTS.

Is it possible to recognize cervical artery dissection on stroke brain MR imaging? A matched case-control study

BACKGROUND AND PURPOSE

Extracranial CAD accounts for nearly 20% of cases of stroke in young adults. The mural hematoma frequently extends cranially to the petrous carotid segment in cCAD or is distally located in vCAD. We hypothesized that standard brain MR imaging could allow the early detection of CAD of the upper portion of carotid and vertebral arteries.

MATERIALS AND METHODS

Our prospectively maintained stroke data base was retrospectively queried to identify all patients with the final diagnosis of CAD. In the 103 consecutive patients studied, analysis of cervical fat-suppressed T1-weighted sequences demonstrated that the mural hematoma was located in the FOV of brain MR imaging in 77 patients. Subsequent to enrollment of a patient, a control patient was extracted from the same data base, within a similar categories for sex, age, NIHSS score, and stroke on DWI. Two blinded observers independently reviewed the 5 brain MR sequences of each examination and determined whether a CAD was present.

RESULTS

Fifty-nine of the 77 patients with CAD (76.6%) and 73 of the 77 patients without CAD (94.8%) were correctly classified. Brain MR imaging demonstrated cCAD more frequently than vCAD in 54/58 (93.1%) and 5/19 (26.3%) patients, respectively, (P < .0001).

CONCLUSIONS

Initial brain MR imaging can correctly suggest CAD in more than two-thirds of patients. This may have practical implications in patients with stroke with delayed cervical MRA or in those who are not initially suspected of having CAD.

Multimodal CT-assisted thrombolysis in patients with acute stroke: a cohort study

BACKGROUND AND PURPOSE

The value of multimodal CT to assist thrombolysis has received little attention in stroke.

METHODS

We assessed prospectively the impact derived from the routine application of CT perfusion and CTA in patients with acute stroke treated consecutively with alteplase. The safety and efficacy of thrombolytic therapy were compared in 106 patients assisted with CT/CTA/CT perfusion (multimodal CT group) and 262 patients assisted without full multimodal brain imaging (control group) during a 5-year period (2005-2009).

RESULTS

Good outcome (modified Rankin scale score ≤2) at 3 months was increased in the multimodal group compared with controls (adjusted OR, 2.88; 95% CI, 1.50-5.52). Multimodal-assisted thrombolysis yielded superior benefits in patients treated beyond 3 hours (adjusted OR, 4.48; 95% CI, 1.68-11.98) than treated within 3 hours (adjusted OR, 1.31; 95% CI, 0.80-2.16; interaction test P=0.043). Mortality (14% and 15%) and symptomatic hemorrhage (5% and 7%) were similar in both groups.

CONCLUSIONS

Multimodal CT use in routine clinical practice may heighten the overall efficacy of thrombolytic therapy in acute ischemic stroke. The benefits seem greater in patients treated >3 hours after stroke onset, but further randomized clinical trials are needed to confirm these findings.

Ischemic stroke

The goal of stroke imaging is to appropriately select patients for different types of therapeutic management in order to optimize outcome and minimize potential complications. To accomplish this, the radiologist has to evaluate each case and tailor an imaging protocol to fit the patient's needs and best answer the clinical question. This review outlines the routinely used, current neuroimaging techniques and their role in the evaluation of the acute stroke patient. The ability of computed tomography and magnetic resonance imaging to adequately evaluate the infarcted brain parenchyma, the cerebral vasculature, and the ischemic, but potentially viable tissue, often referred to as the "ischemic penumbra," is compared The authors outline an imaging algorithm that has been employed at their institution, and briefly review endovascular therapies that can be used in specific patients for stroke treatment.

Experimental stroke research: the contributions of in vivo MRI

Stroke is a disease that develops from the very acute time point of first symptoms during the next several hours and further to a chronic time period of days or even weeks. During this evolution process, a whole series of pathophysiological events takes place. Therefore, the disease is characterized by a continuously changing pathophysiological pattern. In consequence, as the disease develops over time, different imaging modalities must be chosen to accurately describe the status of stroke. In the present chapter, we have divided the evolution of stroke into various dominant steps of the cascade of events, with corresponding time windows. Choice of MRI variables for depiction of the most important aspects during these time windows are presented and their information content is discussed for diagnosis and for investigations into a better understanding of the underlying mechanisms for the disease as well as the relevance of these imaging tools in success assessments for therapeutic strategies.

CT angiographic source images: flow- or volume-weighted?

BACKGROUND AND PURPOSE

CTA-SI have been previously reported to correlate with CBV. We hypothesized that CTA-SI performed by modern multisection CT scanners are CBF-, not CBV-weighted.

MATERIALS AND METHODS

Sixty-four consecutive patients with anterior circulation stroke symptoms were selected from a stroke data base between June 2007 and January 2009. Two independent blinded readers calculated defect volumes of CTA-SI and PCCT, CBF, and CBV images. Spearman correlation of lesion volumes was performed. Linear regression and residual analysis demonstrated factors associated with outliers for CTA or PCCT for CBF and CBV volumes.

RESULTS

We found a strong positive correlation between CTA with CBF (r = 0.89, P < .0001) and between PCCT and CBV (r = 0.79, P < .0001). CTA to CBV (r = 0.5, P < .0001) and PCCT to CBF (r = 0.52, P < .0001) correlations were weaker. Positive CTA outliers had lower ASPECTS (P = .01), larger baseline CTA (149 ± 46 cm(3) versus 83 ± 32 cm(3); P = .002, respectively), and final infarct (190 ± 100 cm(3) versus 80 ± 50 cm(3); P = .09, respectively) volumes than nonoutliers. No baseline features were significantly related to PCCT outliers. There was no difference in the vessel occlusion sites for positive or negative outliers for CTA or PCCT (P = .55 and P = 1.00, respectively).

CONCLUSIONS

Our results indicate that CTA-SI are CBF- rather than CBV-weighted.

The apnea test: rationale, confounders, and criticism

The apnea test is recommended for the diagnosis of brain death. There are several reasons this test should be reconsidered. Confounding factors for performing the test are vaguely and poorly specified. The following 2 confounders are usually present and not considered: potentially reversible high cervical spinal cord injury and central endocrine failure of adrenal and thyroid axes. There are case reports of breathing at a higher partial pressure of arterial carbon dioxide threshold and cases of recovery of breathing after brain death is diagnosed. The test is dangerous for an injured brain in the setting of high intracranial pressure. It can convert viable penumbral brain tissue to irreversibly nonfunctioning tissue via a transient increase in intracranial pressure and no-reflow phenomena. Hyperoxia during the apnea test can further suppress the function of medullary respiratory rhythm centers. Finally, the philosophical rationale for the need to show lack of spontaneous breathing in brain death is lacking.

Cost-effectiveness of multimodal CT for evaluating acute stroke

OBJECTIVE

Multimodal CT, including noncontrast CT (NCCT), CT with contrast, CT angiography (CTA), and perfusion CT (CTP), is increasingly used in acute stroke patients to identify candidates for endovascular therapy. Our goal is to explore the cost-effectiveness of multimodal CT as a diagnostic test.

METHODS

A Markov model compared multimodal CT to NCCT in a hypothetical cohort of nonhemorrhagic stroke patients presenting within 3 hours of symptom onset who were potential IV tPA candidates. Patients who failed to improve after IV tPA or in whom IV tPA was contraindicated were candidates for endovascular therapy. Direct costs (2008 USD), outcomes, and probabilities were obtained from the literature.

RESULTS

For the 3-month time horizon, multimodal CT had lower costs (-$1,716), had greater quality-adjusted life-years (QALYs, 0.004), and was the cost-effective choice 100% of the time for a willingness-to-pay of $100,000/QALY (probabilistic sensitivity analysis). The number needed to screen with multimodal CT to avoid 1 diagnostic angiogram was 2. Over a lifetime, multimodal CT had lower costs (-$2,058), had greater QALYs (0.008), and was cost-effective, with a 90.1% likelihood, for a willingness-to-pay of $100,000/QALY.

CONCLUSIONS

Multimodal CT appears to be a cost-saving screening tool over the short term. However, additional data regarding clinical outcomes following multimodal CT-guided intra-arterial treatment are needed before the long-term cost-effectiveness can be suitably addressed. This analysis can be incorporated into future discussions of multimodal CT as a diagnostic test for unselected patients, within and beyond the 3-hour IV tPA time window.

The missing button sign as a tool for detecting proximal internal carotid artery occlusion

The aim of this study was to develop a simple and reliable sign for detecting proximal internal carotid artery occlusion (ICAO) using conventional CT scanning. The missing button sign (MBS) is defined as the absence of the ICA at the level of the foramen magnum on contrast-enhanced CT (CECT) scans. Two raters independently reviewed random CECT samples from consecutive patients with acute ischaemic stroke. A total of 399 patients with 798 carotid arteries were analysed. Rater A identified the MBS in 41 (5%) of the carotid arteries, and did not identify the MBS in 735 (92%) carotid arteries. Rater B identified the MBS in 45 (6%) of the arteries, and lack of the MBS in 731 (91%) arteries. The kappa value for agreement was 0.90 (95% CI 0.84-0.95). Compared with CT angiography, Rater A's sensitivity, specificity, positive predictive value, and negative predictive value for detecting proximal ICAO were 85%, 100%, 100%, and 99%, respectively, while Rater B's values were 87%, 99%, 93%, and 99%, respectively. This study indicated that the MBS on CECT scanning is both a consistent and specific tool for the early identification of proximal ICAO.

A Comparison of Computed Tomography Perfusion-Guided and Time-Guided Endovascular Treatments for Patients With Acute Ischemic Stroke

Background and Purpose— The role of CT perfusion (CT-P) imaging for the selection of patients with acute ischemic stroke who may benefit from endovascular treatment is not defined. The objective of this study was to determine whether CT-P-guided endovascular treatment improves clinical outcomes compared with standard endovascular treatment based on the time interval between symptom onset and presentation and noncontrast cranial CT imaging.

Methods— A retrospective study was performed comparing the clinical characteristics, complications, and clinical outcomes of patients with acute ischemic stroke who were treated using endovascular modalities based on either CT-P imaging (CT-P-guided) or time interval between symptom onset and presentation and absence of intracerebral hemorrhage or extensive ischemic changes on noncontrast cranial CT scan (time-guided).

Results— The rates of partial and complete recanalization were similar between the CT-P- and time-guided treatment groups (n=61 [88%] versus n=103 [81%]; P =0.52) regardless of whether they received intravenous recombinant tissue plasminogen activator before endovascular treatment. Comparing the CT-P-guided with the time-guided patients, favorable discharge outcome (modified Rankin Scale 0 to 2) was observed in 23 (32%) versus 41 (33%) of the patients, respectively ( P =0.9). In-hospital mortality was observed in 15 (21%) of CT-P- and 29 (23%) of time-guided patients ( P =0.74).

Conclusion— CT-P-guided endovascular treatment did not increase the rate of short-term favorable outcomes among patients with acute ischemic stroke. Prospective studies are required to validate the CT-P criteria and protocols currently in use before incorporating CT-P as a routine modality for patient selection for endovascular treatment.

Prevalence of findings compatible with carotid artery calcifications on dental panoramic radiographs

Cerebrovascular accidents are responsible for killing or disabling more than half a million Americans every year. They are the third leading cause of death in this country. In Germany, the annual stroke incidence reaches 182 cases per 100,000 inhabitants. Stroke there is the fourth leading cause of death. There is a need of finding cost-effective means of decreasing stroke mortality and morbidity. Instruments for early diagnosis are of great humanitarian and economic importance. All possible clinical findings should be taken into account. It is not the demand of this study to present the panoramic radiograph as a screening test method for early diagnosis of atherosclerosis. The aim is to show the potential of this radiograph used in everyday clinical dental practice by the prevalence of radiopaque findings in the carotid region. This study included panoramic dental radiographs of 2,557 patients older than 30 years of age. Fifty-nine percent of the patients were women and 41% were men. The radiographs were adjudged for signs compatible with carotid arterial calcifications appearing as a radiopaque nodular mass adjacent to the cervical vertebrae at or below the intervertebral space C3-4. Of all these radiographs, 4.8% showed radiopaque findings compatible with atherosclerotic lesions. The proportion of women reached 64.8% and that of men reached 35.2%. In accordance to recent literature, the results of this study show that about 5% of the patients show radiological findings compatible with carotid arterial calcifications. Some of these patients at risk for a cerebrovascular accident may be identified in the dentist's office by appropriate review of the panoramic dental radiograph. The suspicion of carotid artery calcifications demands an impetuous referral to an appropriate practitioner who can assist in the control of risk factors and if necessary arrange surgical removal of the carotid arterial plaque. So, the dentist should be aware of this problem and able to make a contribution to stroke prevention.

Use of magnetic resonance imaging to predict outcome after stroke: a review of experimental and clinical evidence

Despite promising results in preclinical stroke research, translation of experimental data into clinical therapy has been difficult. One reason is the heterogeneity of the disease with outcomes ranging from complete recovery to continued decline. A successful treatment in one situation may be ineffective, or even harmful, in another. To overcome this, treatment must be tailored according to the individual based on identification of the risk of damage and estimation of potential recovery. Neuroimaging, particularly magnetic resonance imaging (MRI), could be the tool for a rapid comprehensive assessment in acute stroke with the potential to guide treatment decisions for a better clinical outcome. This review describes current MRI techniques used to characterize stroke in a preclinical research setting, as well as in the clinic. Furthermore, we will discuss current developments and the future potential of neuroimaging for stroke outcome prediction.

Anesthetic concerns in patients with known cerebrovascular insufficiency

This review outlines the perioperative anesthesia considerations of patients with vascular diseases of the central nervous system, including occlusive cerebrovascular diseases with ischemic risks and various cerebrovascular malformations with hemorrhagic potential. The discussion emphasizes perioperative management strategies to prevent complications and minimize their effects if they occur. Planning the anesthetic and perioperative management is predicated on understanding the goals of the therapeutic intervention and anticipating potential problems.

Acute stroke magnetic resonance imaging: current status and future perspective

Cerebral stroke is one of the most frequent causes of permanent disability or death in the western world and a major burden in healthcare system. The major portion is caused by acute ischemia due to cerebral artery occlusion by a clot. The minority of strokes is related to intracerebral hemorrhage or other sources. To limit the permanent disability in ischemic stroke patients resulting from irreversible infarction of ischemic brain tissue, major efforts were made in the last decade. To extend the time window for thrombolysis, which is the only approved therapy, several imaging parameters in computed tomography and magnetic resonance imaging (MRI) have been investigated. However, the current guidelines neglect the fact that the portion of potentially salvageable ischemic tissue (penumbra) is not dependent on the time window but the individual collateral blood flow. Within the last years, the differentiation of infarct core and penumbra with MRI using diffusion-weighted images (DWI) and perfusion imaging (PI) with parameter maps was established. Current trials transform these technical advances to a redefined patient selection based on physiological parameters determined by MRI. This review article presents the current status of MRI for acute stroke imaging. A special focus is the ischemic stroke. In dependence on the pathophysiology of cerebral ischemia, the basic principle and diagnostic value of different MRI sequences are illustrated. MRI techniques for imaging of the main differential diagnoses of ischemic stroke are mentioned. Moreover, perspectives of MRI for imaging-based acute stroke treatment as well as monitoring of restorative stroke therapy from recent trials are discussed.