Automated Segmentation of Intracranial Thrombus on NCCT and CTA in Patients with Acute Ischemic Stroke Using a Coarse-to-Fine Deep Learning Model

BACKGROUND AND PURPOSE

Identifying the presence and extent of intracranial thrombi is crucial in selecting patients with acute ischemic stroke for treatment. This article aims to develop an automated approach to quantify thrombus on NCCT and CTA in patients with stroke.

MATERIALS AND METHODS

A total of 499 patients with large-vessel occlusion from the Safety and Efficacy of Nerinetide in Subjects Undergoing Endovascular Thrombectomy for Stroke (ESCAPE-NA1) trial were included. All patients had thin-section NCCT and CTA images. Thrombi contoured manually were used as reference standard. A deep learning approach was developed to segment thrombi automatically. Of 499 patients, 263 and 66 patients were randomly selected to train and validate the deep learning model, respectively; the remaining 170 patients were independently used for testing. The deep learning model was quantitatively compared with the reference standard using the Dice coefficient and volumetric error. The proposed deep learning model was externally tested on 83 patients with and without large-vessel occlusion from another independent trial.

RESULTS

The developed deep learning approach obtained a Dice coefficient of 70.7% (interquartile range, 58.0%-77.8%) in the internal cohort. The predicted thrombi length and volume were correlated with those of expert-contoured thrombi (r = 0.88 and 0.87, respectively; P < .001). When the derived deep learning model was applied to the external data set, the model obtained similar results in patients with large-vessel occlusion regarding the Dice coefficient (66.8%; interquartile range, 58.5%-74.6%), thrombus length (r = 0.73), and volume (r = 0.80). The model also obtained a sensitivity of 94.12% (32/34) and a specificity of 97.96% (48/49) in classifying large-vessel occlusion versus non-large-vessel occlusion.

CONCLUSIONS

The proposed deep learning method can reliably detect and measure thrombi on NCCT and CTA in patients with acute ischemic stroke.

Outcomes with Endovascular Treatment of Patients with M2 Segment MCA Occlusion in the Late Time Window

BACKGROUND AND PURPOSE

Randomized trials in the late window have demonstrated the efficacy and safety of endovascular thrombectomy in large-vessel occlusions. Patients with M2-segment MCA occlusions were excluded from these trials. We compared outcomes with endovascular thrombectomy in patients with M2-versus-M1 occlusions presenting 6-24 hours after symptom onset.

MATERIALS AND METHODS

Analyses were on pooled data from studies enrolling patients with stroke treated with endovascular thrombectomy 6-24 hours after symptom onset. We compared 90-day functional independence (mRS ≤ 2), mortality, symptomatic intracranial hemorrhage, and successful reperfusion (expanded TICI = 2b-3) between patients with M2 and M1 occlusions. The benefit of successful reperfusion was then assessed among patients with M2 occlusion.

RESULTS

Of 461 patients, 367 (79.6%) had M1 occlusions and 94 (20.4%) had M2 occlusions. Patients with M2 occlusions were older and had lower median baseline NIHSS scores. Patients with M2 occlusion were more likely to achieve 90-day functional independence than those with M1 occlusion (adjusted OR = 2.13; 95% CI, 1.25-3.65). There were no significant differences in the proportion of successful reperfusion (82.9% versus 81.1%) or mortality (11.2% versus 17.2%). Symptomatic intracranial hemorrhage risk was lower in patients with M2-versus-M1 occlusions (4.3% versus 12.2%, P = .03). Successful reperfusion was independently associated with functional independence among patients with M2 occlusions (adjusted OR = 2.84; 95% CI, 1.11-7.29).

CONCLUSIONS

In the late time window, patients with M2 occlusions treated with endovascular thrombectomy achieved better clinical outcomes, similar reperfusion, and lower symptomatic intracranial hemorrhage rates compared with patients with M1 occlusion. These results support the safety and benefit of endovascular thrombectomy in patients with M2 occlusions in the late window.

Strength of Association between Infarct Volume and Clinical Outcome Depends on the Magnitude of Infarct Size: Results from the ESCAPE-NA1 Trial

BACKGROUND AND PURPOSE

Infarct volume is an important predictor of clinical outcome in acute stroke. We hypothesized that the association of infarct volume and clinical outcome changes with the magnitude of infarct size.

MATERIALS AND METHODS

Data were derived from the Safety and Efficacy of Nerinetide in Subjects Undergoing Endovascular Thrombectomy for Stroke (ESCAPE-NA1) trial, in which patients with acute stroke with large-vessel occlusion were randomized to endovascular treatment plus either nerinetide or a placebo. Infarct volume was manually segmented on 24-hour noncontrast CT or DWI. The relationship between infarct volume and good outcome, defined as mRS 0-2 at 90 days, was plotted. Patients were categorized on the basis of visual grouping at the curve shoulders of the infarct volume/outcome plot. The relationship between infarct volume and adjusted probability of good outcome was fitted with linear or polynomial functions as appropriate in each group.

RESULTS

We included 1099 individuals in the study. Median infarct volume at 24 hours was 24.9 mL (interquartile range [IQR] = 6.6-92.2 mL). On the basis of the infarct volume/outcome plot, 4 infarct volume groups were defined (IQR = 0-15 mL, 15.1-70 mL, 70.1-200 mL, >200 mL). Proportions of good outcome in the 4 groups were 359/431 (83.3%), 219/337 (65.0%), 71/201 (35.3%), and 16/130 (12.3%), respectively. In small infarcts (IQR = 0-15 mL), no relationship with outcome was appreciated. In patients with intermediate infarct volume (IQR = 15-200 mL), there was progressive importance of volume as an outcome predictor. In infarcts of > 200 mL, outcomes were overall poor.

CONCLUSIONS

The relationship between infarct volume and clinical outcome varies nonlinearly with the magnitude of infarct size. Infarct volume was linearly associated with decreased chances of achieving good outcome in patients with moderate-to-large infarcts, but not in those with small infarcts. In very large infarcts, a near-deterministic association with poor outcome was seen.

Rivaroxaban versus aspirin for secondary prevention of ischaemic stroke in patients with cancer: a subgroup analysis of the NAVIGATE ESUS randomized trial

BACKGROUND AND PURPOSE

Cancer is a frequent finding in ischaemic stroke patients. The frequency of cancer amongst participants in the NAVIGATE ESUS randomized trial and the distribution of outcome events during treatment with aspirin and rivaroxaban were investigated.

METHODS

Trial participation required a recent embolic stroke of undetermined source. Patients' history of cancer was recorded at the time of study entry. During a mean follow-up of 11 months, the effects of aspirin and rivaroxaban treatment on recurrent ischaemic stroke, major bleeding and all-cause mortality were compared between patients with cancer and patients without cancer.

RESULTS

Amongst 7213 randomized patients, 543 (7.5%) had cancer. Of all patients, 3609 were randomized to rivaroxaban [254 (7.0%) with cancer] and 3604 patients to aspirin [289 (8.0%) with cancer]. The annual rate of recurrent ischaemic stroke was 4.5% in non-cancer patients in the rivaroxaban arm and 4.6% in the aspirin arm [hazard ratio (HR) 0.98, 95% confidence interval (CI) 0.78-1.24]. In cancer patients, the rate of recurrent ischaemic stroke was 7.7% in the rivaroxaban arm and 5.4% in the aspirin arm (HR 1.43, 95% CI 0.71-2.87). Amongst cancer patients, the annual rate of major bleeds was non-significantly higher for rivaroxaban than aspirin (2.9% vs. 1.1%; HR 2.57, 95% CI 0.67-9.96; P for interaction 0.95). All-cause mortality was similar in both groups.

CONCLUSIONS

Our exploratory analyses show that patients with embolic stroke of undetermined source and a history of cancer had similar rates of recurrent ischaemic strokes and all-cause mortality during aspirin and rivaroxaban treatments and that aspirin appeared safer than rivaroxaban in cancer patients regarding major bleeds. www.clinicaltrials.gov (NCT02313909).

Endovascular Treatment Decisions in Patients with M2 Segment MCA Occlusions

BACKGROUND AND PURPOSE

Endovascular therapy in acute ischemic stroke is rapidly evolving. We explored physicians' treatment attitudes and practice in patients with acute ischemic stroke due to M2 occlusion, given the absence of Level-1 guidelines.

MATERIALS AND METHODS

We conducted an international multidisciplinary survey among physicians involved in acute stroke care. Respondents were presented with 10 of 22 case scenarios (4 with proximal M2 occlusions and 1 with a small-branch M2 occlusion) and asked about their treatment approach under A) current local resources, and B) assumed ideal conditions (no monetary or infrastructural restraints). Overall treatment decisions were evaluated; subgroup analyses by physician and patient baseline characteristics were performed.

RESULTS

A total of 607 physicians participated. Most of the respondents decided in favor of endovascular therapy in M2 occlusions, both under current local resources and assumed ideal conditions (65.4% versus 69.6%; P = .017). Under current local resources, older patient age (P < .001), longer time since symptom onset (P < .001), high center endovascular therapy volume (P < .001), high personal endovascular therapy volume (P = .005), and neurosurgeons (P < .001) were more likely to favor endovascular therapy. European respondents were less likely to favor endovascular therapy (P = .001). Under assumed ideal conditions, older patient age (P < .001), longer time since symptom onset (P < .001), high center endovascular therapy volume (P = .041), high personal endovascular therapy volume (P = .002), and Asian respondents were more likely to favor endovascular therapy (P = .037). Respondents with more experience (P = .048) and high annual stroke thrombolysis treatment volume (P = .001) were less likely to favor endovascular therapy.

CONCLUSIONS

Patients with M2 occlusions are considered appropriate candidates for endovascular therapy by most respondents in this survey, especially by those performing endovascular therapy more often and those practicing in high-volume centers.

[NT-PROBNP LEVEL IN PATIENTS WITH LIVER CIRRHOSIS: RELATION TO PORTAL HYPERTENSION AND CARDIOVASCULAR CHANGES]

Cirrhotic cardiomyopathy (CC) is a frequent complication of liver cirrhosis (LC) and characterised by impaired contractile response to stress, altered diastolic relaxation, and QTc prolongation. Symptoms of CC can be masked by edematous ascitic syndrome, high cardiac output, hyperdynamic circulation and preserved left ventricular (LV) ejection fraction at rest. NT-proBNP is a sensitive marker of heart failure in patients with primary heart disease, but its diagnostic value in CC has not been determined. The aim of the study was to evaluate NT-proBNP levels in patients with LC and estimate its relationship with the severity of the main disease, cardiac and hemodynamic dysfunction. The study involved 90 patients with LC (age 49,9±1,92 years). LC decompensation was associated with an increase of end-systolic, end-diastolic volume (ESV, EDV), left ventricular myocardial index (LVMI), cardiac index (CI), decrease E/A and preserve ejection fraction (EF) at rest. Serum NT-proBNP levels in class A, B and C were 109±26.2, 174±17.6, 358±40.1 pg/ml (p˂0.05). The highest NT-proBNP levels were in patients with refractory ascites, severe esophagus varices, hepatorenal syndrome, hypoalbuminemia (374±49.4, 345±33.9, 467±47.4, 323±32.0 pg/ml), the lowest - in pre-ascitics patients (112±23.4 pg/ml). NT-proBNP was correlated with CTP, MELD, serum albumin, portal vein diameter (r= 0.550, 0.429, -0.334, 0.237, p˂0.05), eGFR, CI, EDV, LVMI, E/A (r= 0.419, 0.401, 0.296, 0.233, 0.325, p˂0.05). Thus, elevated levels of NT-proBNP may be an indicator of cardiac dysfunction in patients with LC.

FROM THE PERSISTENT EPSTEIN-BARR VIRUS INFECTION TO ANGIOIMMUNOBASTIC T-CELL LYMPHOMA - DRAMATIC CONVERGENCE. ANALYSIS OF THE CLINICAL CASE

The problem of timely diagnosis and effective treatment of EBD-associated lymphoproliferative diseases is associated with a large variety of morphological and immunological manifestations, which require a powerful, highly specific immunohistochemical and molecular genetic research methods for the correct assessment. The article elucidates current information about the pathogenesis of oncogenic EBV infection, the main clinical forms of associated lymphoproliferative processes, their main diagnostic criteria. The given clinical case of angioimmunoblastic T cell lymphoma clearly demonstrates the complexity of the diagnostic process, underestimation of informativity and the importance of molecular genetic research, which led to the rejection of chemotherapeutic treatment, the rapid progression of the terminal stage of lymphoproliferative disease with the development of polyorganic failure and lifetime destruction, necrosis of the structural components of the tumor, as a result of which during the autopsy of morphological signs of lymphoma was not detected.

Nonuniform allocation of hippocampal neurons to place fields across all hippocampal subfields

The mechanisms governing how the hippocampus selects neurons to exhibit place fields are not well understood. A default assumption in some previous studies was the uniform random draw with replacement (URDWR) model, which, theoretically, maximizes spatial "pattern separation", and predicts a Poisson distribution of the numbers of place fields expressed by a given cell per unit area. The actual distribution of mean firing rates exhibited by a population of hippocampal neurons, however, is approximately exponential or log-normal in a given environment and these rates are somewhat correlated across multiple places, at least under some conditions. The advantage of neural activity-dependent immediate-early gene (IEG) analysis, as a proxy for electrophysiological recording, is the ability to obtain much larger samples of cells, even those whose activity is so sparse that they are overlooked in recording studies. Thus, a more accurate representation of the activation statistics can potentially be achieved. Some previous IEG studies that examined behavior-driven IEG expression in CA1 appear to support URDWR. There was, however, in some of the same studies, an under-recruitment of dentate gyrus granule cells, indicating a highly skewed excitability distribution, which is inconsistent with URDWR. Although it was suggested that this skewness might be related to increased excitability of recently generated granule cells, we show here that CA1, CA3, and subiculum also exhibit cumulative under-recruitment of neurons. Thus, a highly skewed excitability distribution is a general principle common to all major hippocampal subfields. Finally, a more detailed analysis of the frequency distributions of IEG intranuclear transcription foci suggests that a large fraction of hippocampal neurons is virtually silent, even during sleep. Whether the skewing of the excitability distribution is cell-intrinsic or a network phenomenon, and the degree to which this excitability is fixed or possibly time-varying are open questions for future studies. © 2016 Wiley Periodicals, Inc.

Emergency noninvasive angiography for acute intracerebral hemorrhage

Spontaneous ICH is a devastating condition and is associated with significant mortality in the acute phase due to ongoing hemorrhage and hematoma expansion. A growing body of evidence suggests that there may be considerable utility in performing noninvasive vascular imaging during the acute-to-early phase of ICH. CTA has become widely available and is sensitive and specific for detecting vascular causes of secondary ICH such as aneurysms, arteriovenous malformations, dural arteriovenous fistulas, intracranial dissections, and neoplasm. CT venography can also diagnose dural sinus thrombosis presenting as hemorrhagic infarction. Recent data from stroke populations demonstrate a relatively low risk to patients when contrast is administered in the absence of a known serum creatinine. Detection of acute contrast extravasation within the hematoma ("spot sign") with CT angiography is predictive of subsequent hematoma expansion and is associated with increased morbidity and mortality. Risk stratification based on acute CTA can inform and expedite decision-making regarding intensive care unit admission, blood pressure control, correction of coagulopathy, and neurosurgical consultation. Noninvasive vascular imaging should be considered as an important component of the initial diagnostic work-up for patients presenting with acute ICH.

Quantification of thrombus hounsfield units on noncontrast CT predicts stroke subtype and early recanalization after intravenous recombinant tissue plasminogen activator

BACKGROUND AND PURPOSE

Little is known about the factors that determine recanalization after intravenous thrombolysis. We assessed the value of thrombus Hounsfield unit quantification as a predictive marker of stroke subtype and MCA recanalization after intravenous rtPA treatment.

MATERIALS AND METHODS

NCCT scans and CTA were performed on patients with MCA acute stroke within 4.5 hours of symptom onset. Demographics, stroke severity, vessel hyperattenuation, occlusion site, thrombus length, and time to thrombolysis were recorded. Stroke origin was categorized as LAA, cardioembolic, or indeterminate according to TOAST criteria. Two blinded neuroradiologists calculated the Hounsfield unit values for the thrombus and contralateral MCA segment. We used ROC curves to determine the rHU cutoff point to discriminate patients with successful recanalization from those without. We assessed the accuracy (sensitivity, specificity, and positive and negative predictive values) of rHU in the prediction of recanalization.

RESULTS

Of 87 consecutive patients, 45 received intravenous rtPA and only 15 (33.3%) patients had acute recanalization. rHU values and stroke mechanism were the highest predictive factors of recanalization. The Matthews correlation coefficient was highest for rHU (0.901). The sensitivity, specificity, and positive and negative predictive values for lack of recanalization after intravenous rtPA for rHU ≤ 1.382 were 100%, 86.67%, 93.75%, and 100%, respectively. LAA thrombi had lower rHU than cardioembolic and indeterminate stroke thrombi (P = .004).

CONCLUSIONS

The Hounsfield unit thrombus measurement ratio can predict recanalization with intravenous rtPA and may have clinical utility for endovascular treatment decision making.

Achieving faster recanalization times by IA thrombolysis in acute ischemic stroke: where should we direct our efforts?

Faster recanalization correlates with better outcomes in acute ischemic stroke. We analyzed times from arrival in ER to end of treatment in patients undergoing endovascular treatment for acute ischemic stroke at our institution.We retrospectively studied patients who underwent IA procedures for stroke from 2005 to 2009 noting the times of arrival to ER, CT scan, arrival to DSA, arterial puncture and recanalization from our endovascular database. A subgroup analysis was performed based on administration of GA, use of mechanical devices and whether the procedure was performed during regular hours or after hours.Of 101 patients, 53 were male, with a median age of 66 years (range 18-87). There were 81 anterior circulation strokes. Median ER to CT time was 22 min (2-1025), CT to DSA arrival time 80 min (range 4-990), DSA arrival to puncture time 24 min (range 0-75) and puncture to recanalization time 84 min (range 11-206). 23.3% of patients had an ER to CT time interval of > 60 min and 71.3 % had a CT to DSA time interval of > 60 min contributing to significant in-hospital delays. For subgroup analysis the Mann-Whitney test was used. No significant differences in CT to DSA arrival (p=0.8), DSA arrival to puncture (p=0.1) and puncture to recanalization (p=0.59) times were noted between patients with and without GA. No significant difference was noted in puncture to recanalization times with or without device (p=0.78). 39 cases were done during regular (R) hours and 62 after (A) hours. Median ER to CT time (R=18 min, A = 27 min, p 0.02), CT to DSA arrival time (R=64 min, A=90 min, p 0.004) and DSA arrival to puncture time (R=18 min, A=25 min, p 0.003) was significantly higher after hours.ER to CT and CT to DSA arrival times in patients undergoing endovascular stroke therapy show wide variability and therefore, considerable scope for reduction. Time differences during regular and after hours should serve as a reminder to make efforts to reduce overall ischemic times in spite of staffing patterns and resource availability.

Toward Growing III-V Clusters with Metalorganic Precursors

The present work reports on the formation of GaN-containing clusters from metalorganic precursors by combining pulsed laser photolysis and pulsed nozzle methods. Ammonia (NH3) and triethylgallium (C2H5)3Ga (TEG) or trimethylgallium (CH3)3Ga (TMG) with He, Ar, or N2 as the carrier gas are introduced into a high vacuum chamber via a specialized dual pulsed nozzle source. The light from an ArF excimer laser (193 nm, 23 ns FWHM) is focused into the mixing and reaction region of the nozzle source, and the products are then mass analyzed with a quadrupole mass spectrometer. Efficient laser-assisted growth of (GaN)x-containing clusters is shown with this technique.

Equipoise among recanalization strategies

Modern acute ischemic stroke therapy is based on the premise that recanalization and subsequent reperfusion are essential for the preservation of brain tissue and favorable clinical outcomes. We outline key issues that we think underlie equipoise regarding the comparative clinical efficacy of IV recombinant tissue-type plasminogen activator (rt-PA) and intra-arterial (IA) reperfusion therapies for acute ischemic stroke. On the one hand, IV rt-PA therapy has the benefit of speed with presumed lower rates of recanalization of large artery occlusions as compared to IA methods. More recent reports of major arterial occlusions treated with IV rt-PA, as measured by transcranial Doppler and magnetic resonance angiography, demonstrate higher rates of recanalization. Conversely, IA therapies report higher recanalization rates, but are hampered by procedural delays and risks, even failing to be applied at all in occasional patients where time to reperfusion remains a critical factor. Higher rates of recanalization in IA trials using clot-removal devices have not translated into improved patient functional outcome as compared to trials of IV therapy. Combined IV-IA therapy promises to offer advantages of both, but perhaps only when applied in the timeliest of fashions, compared to IV therapy alone. Where equipoise exists, randomizing subjects to either IV rt-PA therapy or IV therapy followed by IA intervention, while incorporating new interventions into the study design, is a rational and appropriate research approach.

Neurologic complications after coronary artery bypass grafting

Although outcomes from coronary artery bypass grafting (CABG) surgery have improved in general, there has been little or no improvement in the incidence of postoperative stroke or neurologic dysfunction. Several studies have identified factors that increase the CABG patient's risk for developing a stroke and neurologic complications. It is important to identify those patients at increased risk and differentiate among stroke, delirium, and seizures. Post-CABG patients need to be monitored for neurological dysfunction with appropriate assessments. Neurologic complications must be appropriately managed to optimize patient recovery.