Combined carotid and transcranial color-coded sonography in acute ischemic stroke

Diagnostic feasibility of middle cerebral artery stenosis or occlusion evaluated by TCCS and CEUS: Repeatability, reproducibility, and diagnostic agreement with DSA

AIM

This study aimed to evaluate the feasibility of transcranial color-coded sonography (TCCS) and contrast-enhanced ultrasound (CEUS) in assessing middle cerebral artery (MCA) stem stenosis or occlusion compared to digital subtraction angiography (DSA).

METHODS

A total of 48 cases including 96 MCAs suspected stem stenosis or obstruction in the MCA were assessed by TCCS, CE-TCCS, and DSA. The diameters of the most severe stenosis (Ds), proximal normal artery (Dn), and diameter stenosis rate of MCA were measured using both the color doppler flow imaging (CDFI) modality of TCCS or CEUS and the CEUS imaging modality. The intraclass correlation coefficients (ICCs) and 95 % confidence intervals (CI) were evaluated, and a weighted Kappa value was used to evaluate the intra-observer agreement, inter-observer agreement, agreement between CDFI modality and DSA stenosis or occlusion, and agreement between CEUS imaging modality and DSA stenosis or occlusion.

RESULTS

The ICC results indicated excellent repeatability and reproducibility (all ICCs > 0.75; weighted Kappa values >0.81). Compared with DSA, the weighted Kappa values and 95 % CIs of stenosis (the first measurement was taken by two observers) of CDFI modality and CEUS imaging modality were 0.175 (0.041, 0.308) and 0.779 (0.570, 0.988) for observers A and 0.181 (0.046, 0.316) and 0.779 (0.570, 0.988) for observers B respectively.

CONCLUSION

This study indicates that inter- and intra-observer agreements were good for the direct method of measuring percentages of MCA stenosis by TCCS and CEUS. CEUS imaging modality is a new and reliable imaging modality approach to evaluate the MCAs stenosis and occlusion.

Applying Machine Learning to Carotid Sonographic Features for Recurrent Stroke in Patients With Acute Stroke

BACKGROUND

Although carotid sonographic features have been used as predictors of recurrent stroke, few large-scale studies have explored the use of machine learning analysis of carotid sonographic features for the prediction of recurrent stroke.

METHODS

We retrospectively collected electronic medical records of enrolled patients from the data warehouse of China Medical University Hospital, a tertiary medical center in central Taiwan, from January 2012 to November 2018. We included patients who underwent a documented carotid ultrasound within 30 days of experiencing an acute first stroke during the study period. We classified these participants into two groups: those with non-recurrent stroke (those who has not been diagnosed with acute stroke again during the study period) and those with recurrent stoke (those who has been diagnosed with acute stroke during the study period). A total of 1,235 carotid sonographic parameters were analyzed. Data on the patients' demographic characteristics and comorbidities were also collected. Python 3.7 was used as the programming language, and the scikit-learn toolkit was used to complete the derivation and verification of the machine learning methods.

RESULTS

In total, 2,411 patients were enrolled in this study, of whom 1,896 and 515 had non-recurrent and recurrent stroke, respectively. After extraction, 43 features of carotid sonography (36 carotid sonographic parameters and seven transcranial color Doppler sonographic parameter) were analyzed. For predicting recurrent stroke, CatBoost achieved the highest area under the curve (0.844, CIs 95% 0.824-0.868), followed by the Light Gradient Boosting Machine (0.832, CIs 95% 0.813-0.851), random forest (0.819, CIs 95% 0.802-0.846), support-vector machine (0.759, CIs 95% 0.739-0.781), logistic regression (0.781, CIs 95% 0.764-0.800), and decision tree (0.735, CIs 95% 0.717-0.755) models.

CONCLUSION

When using the CatBoost model, the top three features for predicting recurrent stroke were determined to be the use of anticoagulation medications, the use of NSAID medications, and the resistive index of the left subclavian artery. The CatBoost model demonstrated efficiency and achieved optimal performance in the predictive classification of non-recurrent and recurrent stroke.

The use of transcranial ultrasound and clinical assessment to diagnose ischaemic stroke due to large vessel occlusion in remote and rural areas

Rapid endovascular thrombectomy, which can only be delivered in specialist centres, is the most effective treatment for acute ischaemic stroke due to large vessel occlusion (LVO). Pre-hospital selection of these patients is challenging, especially in remote and rural areas due to long transport times and limited access to specialist clinicians and diagnostic facilities. We investigated whether combined transcranial ultrasound and clinical assessment (“TUCA” model) could accurately triage these patients and improve access to thrombectomy. We recruited consecutive patients within 72 hours of suspected stroke, and performed non-contrast transcranial colour-coded ultrasonography within 24 hours of brain computed tomography. We retrospectively collected clinical information, and used hospital discharge diagnosis as the “gold standard”. We used binary regression for diagnosis of haemorrhagic stroke, and an ordinal regression model for acute ischaemic stroke with probable LVO, without LVO, transient ischaemic attacks (TIA) and stroke mimics. We calculated sensitivity, specificity, positive and negative predictive values and performed a sensitivity analysis. We recruited 107 patients with suspected stroke from July 2017 to December 2019 at two study sites: 13/107 (12%) with probable LVO, 50/107 (47%) with acute ischaemic stroke without LVO, 18/107 (17%) with haemorrhagic stroke, and 26/107 (24%) with stroke mimics or TIA. The model identified 55% of cases with probable LVO who would have correctly been selected for thrombectomy and 97% of cases who would not have required this treatment (sensitivity 55%, specificity 97%, positive and negative predictive values 75% and 93%, respectively). Diagnostic accuracy of the proposed model was superior to the clinical assessment alone. These data suggest that our model might be a useful tool to identify pre-hospital patients requiring mechanical thrombectomy, however a larger sample is required with the use of CT angiogram as a reference test.

Diagnostic value of transcranial ultrasonography for selecting subjects with large vessel occlusion: a systematic review

Introduction

A number of pre-hospital clinical assessment tools have been developed to triage subjects with acute stroke due to large vessel occlusion (LVO) to a specialised endovascular centre, but their false negative rates remain high leading to inappropriate and costly emergency transfers. Transcranial ultrasonography may represent a valuable pre-hospital tool for selecting patients with LVO who could benefit from rapid transfer to a dedicated centre.

Methods

Diagnostic accuracy of transcranial ultrasonography in acute stroke was subjected to systematic review. Medline, Embase, PubMed, Scopus, and The Cochrane Library were searched. Published articles reporting diagnostic accuracy of transcranial ultrasonography in comparison to a reference imaging method were selected. Studies reporting estimates of diagnostic accuracy were included in the meta-analysis.

Results

Twenty-seven published articles were selected for the systematic review. Transcranial Doppler findings, such as absent or diminished blood flow signal in a major cerebral artery and asymmetry index ≥ 21% were shown to be suggestive of LVO. It demonstrated sensitivity ranging from 68 to 100% and specificity of 78–99% for detecting acute steno-occlusive lesions. Area under the receiver operating characteristics curve was 0.91. Transcranial ultrasonography can also detect haemorrhagic foci, however, its application is largely restricted by lesion location.

Conclusions

Transcranial ultrasonography might potentially be used for the selection of subjects with acute LVO, to help streamline patient care and allow direct transfer to specialised endovascular centres. It can also assist in detecting haemorrhagic lesions in some cases, however, its applicability here is largely restricted. Additional research should optimize the scanning technique. Further work is required to demonstrate whether this diagnostic approach, possibly combined with clinical assessment, could be used at the pre-hospital stage to justify direct transfer to a regional thrombectomy centre in suitable cases.

Diagnostic accuracy of clinical tools for assessment of acute stroke: a systematic review

INTRODUCTION

Recanalisation therapy in acute ischaemic stroke is highly time-sensitive, and requires early identification of eligible patients to ensure better outcomes. Thus, a number of clinical assessment tools have been developed and this review examines their diagnostic capabilities.

METHODS

Diagnostic performance of currently available clinical tools for identification of acute ischaemic and haemorrhagic strokes and stroke mimicking conditions was reviewed. A systematic search of the literature published in 2015-2018 was conducted using PubMed, EMBASE, Scopus and The Cochrane Library. Prehospital and in-hospital studies with a minimum sample size of 300 patients reporting diagnostic accuracy were selected.

RESULTS

Twenty-five articles were included. Cortical signs (gaze deviation, aphasia and neglect) were shown to be significant indicators of large vessel occlusion (LVO). Sensitivity values for selecting subjects with LVO ranged from 23 to 99% whereas specificity was 24 to 97%. Clinical tools, such as FAST-ED, NIHSS, and RACE incorporating cortical signs as well as motor dysfunction demonstrated the best diagnostic accuracy. Tools for identification of stroke mimics showed sensitivity varying from 44 to 91%, and specificity of 27 to 98% with the best diagnostic performance demonstrated by FABS (90% sensitivity, 91% specificity). Hypertension and younger age predicted intracerebral haemorrhage whereas history of atrial fibrillation and diabetes were associated with ischaemia. There was a variation in approach used to establish the definitive diagnosis. Blinding of the index test assessment was not specified in about 50% of included studies.

CONCLUSIONS

A wide range of clinical assessment tools for selecting subjects with acute stroke has been developed in recent years. Assessment of both cortical and motor function using RACE, FAST-ED and NIHSS showed the best diagnostic accuracy values for selecting subjects with LVO. There were limited data on clinical tools that can be used to differentiate between acute ischaemia and haemorrhage. Diagnostic accuracy appeared to be modest for distinguishing between acute stroke and stroke mimics with optimal diagnostic performance demonstrated by the FABS tool. Further prehospital research is required to improve the diagnostic utility of clinical assessments with possible application of a two-step clinical assessment or involvement of simple brain imaging, such as transcranial ultrasonography.

The use of neurovascular ultrasound versus digital subtraction angiography in acute ischemic stroke

Cervical and intracranial arterial evaluation is an important issue for acute ischemic stroke (IS).

OBJECTIVE

Compare the use of the neurovascular ultrasound examination (NVUE) to digital subtraction angiography (DSA) in acute IS patients for diagnosing significant extracranial and intracranial arteriopathy.

METHOD

Nonconsecutive patients with IS or transient ischemic attack admitted within 12 hours of the onset of symptoms were evaluated retrospectively. Standardized NVUE and DSA were done in all patients within the first 120 hours of hospital admission.

RESULTS

Twenty-four patients were included in the study. Compared to DSA, the NVUE demonstrated 94.7% sensitivity and 100% specificity for identifying symptomatic extracranial and/or intracranial arteriopathy.

CONCLUSION

The standardized NVUE technique demonstrated high sensitivity and specificity compared to DSA for diagnosing arterial abnormalities in acute IS patients.

Focused examination of cerebral blood flow in peri-resuscitation: a new advanced life support compliant concept—an extension of the focused echocardiography evaluation in life support examination

Aim

To introduce a new concept of the extension of focused echocardiography evaluation in life support (FEEL) with advanced life support (ALS)-compliant duplex sonography of the extracranial internal carotid artery (ICA) blood flow velocity for monitoring of cerebral blood circulation during peri-resuscitation.

Concept and results

With respect to pulseless electrical activity states, the question of adequate cerebral blood flow (CBF) cannot be answered by echocardiography alone. Pulse checks are unreliable. To build up a concept for assessing CBF, we analyzed duplex sonography workflow in three adults on the intensive care unit (postoperative, cardiogenic shock, cardiac standstill), and in simulated procedures. We decided to use duplex flow velocity of the ICA, for it is an accepted measurement for estimating CBF and it seems to be easy to obtain a window and interpretation during peri-resuscitation. The presence of an arterial blood flow pattern and an end-diastolic flow velocity of more than 20 cm/s, arbitrarily set, is considered to indicate sufficient CBF. The method of ICA flow velocity analysis during peri-resuscitation was tentatively added to the FEEL concept and is described with algorithm, workflow and three cases. This method may give an assist to answer the question, if CBF is sufficient, when myocardial wall motion is detectable in peri-resuscitation care.

Conclusion

This new concept of an ALS-conformed analysis of ICA blood flow velocity by duplex sonography may provide a simple, fast applicable and inexpensive method to qualitatively assess CBF in the peri-resuscitation setting.

Hyperoxia potentiated sonothrombolysis as a method of acute ischemic stroke therapy

The main goal in the treatment of acute ischemic stroke is prompt arterial recanalization. Thrombolysis with recombinant tissue plasminogen activator (rtPA) is efficient in humans, but shows significant problems including slow and incomplete recanalization and frequent bleeding complications. Limited therapeutic window (the first three hours after onset) is the major limitation resulting in reach too few patients. Therefore, adjunctive therapies extending the reperfusion time window, increasing efficacy and reducing side effects of rtPA are needed. Ultrasound augmentation of rtPA-mediated thrombolysis is suggested to overcome some of these problems, but low-frequency ultrasound (less than 1 MHz) is not safe and high frequency ultrasound (2 MHz) is not much effective. We suggest that normobaric hyperoxia (NBO) may increase the efficacy of ultrasound and rtPA combination in addition to its own efficacy in acute ischemic stroke. Briefly, NBO increases arterial partial oxygen pressure (pO(2)) significantly up to 6-fold. Increase of pO(2) results in an increase of dissolved oxygen in the blood according to Henry's law. Enhanced dissolved oxygen increases gas nuclei formation around and inside of the clot, and decreases the Blake threshold. Under ultrasound field, these small gas nuclei form nano bubbles which fuel inertial cavitation as substrates, and therefore increase the clot fragmentation and lysis. This hypothesis has not been tested so far. The combination of rtPA, therapeutic ultrasound and NBO may be more efficacious than rtPA alone or its combination with ultrasound as acute stroke treatment modality, because each has different and probably additive mechanism of action.

Absent Middle Cerebral Artery Signal in Transcranial Color-Coded Sonography: A Reliable Indicator of Occlusion?

BACKGROUND

Assess the accuracy of transcranial color-coded sonography (TCCS) for detecting middle cerebral artery (MCA) stem occlusion and compare it with cerebral angiography.

METHODS

This study enrolled a series of patients who received TCCS and cerebral angiography at the Department of Neurology in Chang Gung Memorial Hospital, Linkou Medical Center, Taoyuan, Taiwan, between January 1997 and July 2003. MCA stem occlusion was diagnosed based on digital subtraction angiography and/or computed tomographic angiography. The effect of the supplying artery on the insonation of MCA stem was considered. The sonographic criteria for MCA stem occlusion were defined as absent MCA stem signal + visible signal on the reference arteries, including ipsilateral posterior cerebral artery, ipsilateral anterior cerebral artery or contralateral MCA stem.

RESULTS

A total of 419 consecutive patients were enrolled. Factors that significantly influenced MCA stem insonation included > or =50% ipsilateral carotid artery stenosis, > or =50% MCA stem stenosis, female gender, and age > or =60 years. Comparing patients with <50% and those with > or =50% carotid stenosis, the MCA stem insonation rate was significantly reduced from 69.1% to 45.6% (p < 0.001). In patients with <50% ipsilateral carotid artery stenosis, the sonographic criteria had a positive predictive value of 10.5% and a negative predictive value of 98.9%, and could predict MCA stem occlusion with high specificity but low sensitivity (specificity = 89.6, sensitivity = 54.5, overall accuracy = 88.9, p < 0.001).

CONCLUSION

Absent MCA stem signal may result from MCA stem occlusion/tight stenosis and tight stenosis of ipsilateral carotid arteries, and has a limited value in detecting MCA stem occlusion. TCCS can be useful in identifying nonoccluded MCA stem, and cerebral angiography is necessary to confirm MCA stem occlusion.

Diagnosis of middle cerebral artery occlusive lesions with contrast-enhanced transcranial color-coded real-time sonography in acute stroke

It is useful to evaluate the occlusive lesions of middle cerebral artery (MCA) occlusion with transcranial color-coded real-time sonography (TCCS). However, TCCS criteria for locating the site of the MCA occlusion has, as yet, remained unclear. The aim of the present study was to establish TCCS criteria for MCA occlusive lesions. We prospectively performed contrast-enhanced TCCS (CE-TCCS) in 75 consecutive acute stroke patients within 24 h of digital subtraction angiography. Patients were divided into four groups: occlusion of the MCA stem (MO group, n=12); occlusion of the MCA branch (MBO group, n=10); stenosis of the MCA stem (MS group, n=9); and no occlusive or stenotic lesions (control group, n=44). The following parameters were measured: peak systolic velocity (PSV) and end diastolic velocity (EDV) of bilateral MCA stems, and ED-ratio (the side-to-side ratio of the EDV). We establish the CE-TCCS criteria for MCA occlusive lesions using the sensitivity-specificity curve analysis. A PSV of 170 cm/s distinguished MCA stenosis from other groups (positive and negative predictive values and the accuracies were 100%, 99.0% and 99.1%, respectively). An EDV of 26 cm/s differentiated MO or MBO from the other groups (positive and negative predictive values and the accuracies were 84.6%, 100% and 96.5%, respectively). An ED-ratio of 2.5 discriminated MO from the MBO group (positive and negative predictive values and the accuracies were 88.9%, 85.7% and 87.5%, respectively). Measurement of MCA stem flow velocity with CE-TCCS can identify MCA stem stenosis and occlusion, as well as MCA branch occlusion.

Yield and Accuracy of Urgent Combined Carotid/Transcranial Ultrasound Testing in Acute Cerebral Ischemia

Background and Purpose— We routinely perform an urgent bedside neurovascular ultrasound examination (NVUE) with carotid/vertebral duplex and transcranial Doppler (TCD) in patients with acute cerebral ischemia. We aimed to determine the yield and accuracy of NVUE to identify lesions amenable for interventional treatment (LAITs).

Methods— NVUE was performed with portable carotid duplex and TCD using standardized fast-track (<15 minutes) insonation protocols. Digital subtraction angiography (DSA) was the gold standard for identifying LAIT. These lesions were defined as proximal intra- or extracranial occlusions, near-occlusions, ≥50% stenoses or thrombus in the symptomatic artery.

Results— One hundred and fifty patients (70 women, mean age 66±15 years) underwent NVUE at median 128 minutes after symptom onset. Fifty-four patients (36%) received intravenous or intra-arterial thrombolysis (median National Institutes of Health Stroke Scale (NIHSS) score 14, range 4 to 29; 81% had NIHSS ≥10 points). NVUE demonstrated LAITs in 98% of patients eligible for thrombolysis, 76% of acute stroke patients ineligible for thrombolysis (n=63), and 42% in patients with transient ischemic attack (n=33), P <0.001. Urgent DSA was performed in 30 patients on average 230 minutes after NVUE. Compared with DSA, NVUE predicted LAIT presence with 100% sensitivity and 100% specificity, although individual accuracy parameters for TCD and carotid duplex specific to occlusion location ranged 75% to 96% because of the presence of tandem lesions and 10% rate of no temporal windows.

Conclusions— Bedside neurovascular ultrasound examination, combining carotid/vertebral duplex with TCD yields a substantial proportion of LAITs in excellent agreement with urgent DSA.

Vertebral artery occlusion in duplex color-coded ultrasonography

BACKGROUND AND PURPOSE

To establish the diagnostic criteria for the site of occlusion in the vertebral arteries (VAs) using duplex color-coded ultrasonography.

METHODS

In 128 consecutive patients who underwent conventional cerebral angiography, we prospectively measured the diameter, mean flow velocity (MV), peak systolic flow velocity, and end-diastolic flow velocity of both VAs. The diameter-ratio (diameter of contralateral VA divided by that of target VA) and MV-ratio (MV of contralateral VA divided by that of target VA) were determined. Based on the angiographic findings, we classified the VAs into 4 types (5 groups) as follows: (1) the origin of VA occlusion (Origin group: n=9); (2) VA occlusion before branching into the posterior inferior cerebellar artery (PICA) (Before group: n=10); (3A) symptomatic VA occlusion after branching into the PICA (After group: n=12); (3B) asymptomatic or hypoplastic occlusive VA after branching into the PICA (PICA end group: n=15); and (4) no significant occlusive lesions in the VA (Control group: n=194).

RESULTS

No flow signals in the VAs apparently indicated the Origin group. Preserved peak systolic flow velocity but end-diastolic flow velocity of zero cm/s indicated the Before group. MV <18 cm/s and MV-ratio > or =1.4 indicated the PICA end group or After group. Furthermore, these groups could be distinguished as follows: a diameter-ratio <1.4 indicated the After group. A diameter-ratio > or =1.4 indicated the PICA end group. Either MV > or =18 cm/s or MV <18 cm/s in combination with MV-ratio <1.4 indicated the Control group.

CONCLUSIONS

Duplex color-coded ultrasonography can accurately diagnose the site of VA occlusion.

Cerebral Angiography in the Assessment of Acute Cerebral Ischemia: Guidelines and Recommendations

Catheter-based cerebral angiography remains an essential tool for evaluating patients with acute cerebral ischemia. Noninvasive vascular imaging techniques have yet to achieve the accuracy and wide availability necessary for this purpose. Angiography is rarely indicated when patients present within the short 3-hour time window for treatment with intravenous alteplase. For the many patients who present later in their course, however, angiography is useful for the accurate evaluation of the cerebral vasculature. In addition, angiography serves as the foundation for the endovascular therapies that may be performed to treat acute ischemic stroke beyond the 3-hour time window.