Transcranial Doppler sonography for detecting stenosis or occlusion of intracranial arteries in people with acute ischaemic stroke

Transcranial Doppler ultrasonography to evaluate cerebral hemodynamic changes in neurocysticercosis

BACKGROUND

 Arteritis is a complication of neurocysticercosis (NCC), which is not well known and could trigger strokes. The transcranial Doppler ultrasound (TCD) is a noninvasive method for detecting, staging, and monitoring cerebrovascular diseases. Nonetheless, the utility of TCD to evaluate cerebral hemodynamic changes, suggesting vasculitis associated with NCC remains uncertain.

OBJECTIVE

 To evaluate cerebral hemodynamic changes using TCD in patients with subarachnoid and parenchymal NCC.

METHODS

 There were 53 patients with NCC evaluated at a reference hospital for neurological diseases included (29 with subarachnoid and 24 with parenchymal). Participants underwent a clinical interview and serology for cysticercosis and underwent TCD performed within 2 weeks of enrollment. Mean flow velocity, peak systolic velocity, end diastolic velocity, and pulsatility index were recorded.

RESULTS

 Among the participants, there were 23 (43.4%) women, with a median age of 37 years (IQR: 29-48). Cerebral hemodynamic changes suggesting vasculitis were detected in 12 patients (22.64%); the most compromised vessel was the middle cerebral artery in 11 (91.67%) patients. There were more females in the group with sonographic signs of vasculitis (10/12, 83.33% vs. 13/41, 31.71%; p = 0.002), and this was more frequent in the subarachnoid NCC group (9/29, 31.03% vs. 3/24, 12.5%; p = 0.187), although this difference did not reach statistical significance.

CONCLUSION

 Cerebral hemodynamic changes suggestive of vasculitis are frequent in patients with NCC and can be evaluated using TCD.

Cerebral pseudoinfarction due to venoarterial extracorporeal membrane oxygenation: A case report

BACKGROUND

Neurological complications are common in the management of venoarterial extracorporeal membrane oxygenation (VA-ECMO), with most patients requiring sedation and intubation, limiting the assessment of neurological function. There-fore, we must rely on advanced neuroimaging techniques, such as computed tomography angiography (CTA) and computed tomography perfusion (CTP). Because ECMO changes the normal blood flow pattern, it may interfere with the contrast medium in some special cases, leading to artifacts and ultimately mis-leading clinical decisions.

CASE SUMMARY

A 61-year-old man presented to a local hospital with chest tightness and pain 1 d prior to presentation. The patient was treated with VA-ECMO after sudden car-diac and respiratory arrest at a local hospital. For further treatment, the patient was transferred to our hospital. The initial consciousness assessment was not clear, and routine CTP was performed to understand the intracranial changes, which suggested a large area of cerebral infarction on the right side; however, the cerebral oxygen was not consistent with the CTP results, and the reexamination of CTA still suggested a right cerebral infarction. To identify this difference, bedside transcranial Doppler was performed, and the blood flow on both sides was different. By reducing the ECMO flow, CTP reexamination showed that the results were normal and consistent with the clinical results. On day 3, the patient was alert and showed good limb movements.

CONCLUSION

In patients with peripheral VA-ECMO, cerebral perfusion confirmed by CTP and CTA may lead to false cerebral infarction.

Middle Cerebral Artery Dissection: A Report of Two Cases With Treatments and Outcomes

In the present report, we describe two cases of right-sided M1 segment middle cerebral artery dissection in a 51-year-old Asian female and in a 28-year-old Caucasian male patient with no previous history of ischemic stroke or known intracranial atherosclerosis presenting with acute unilateral headache progressing to severe multifocal hemispheric infarction with nearly complete one-sided motor paralysis. In both patients, a middle cerebral artery dissection was detected on angiography; they were given exclusively medical therapy: patient 1 was not eligible to reperfusive therapies and was treated with a three-month course of acetylsalicylic acid and clopidogrel combined with low-dose enoxaparin, while patient 2 was initially treated with intravenous alteplase with no hemorrhagic complications and was later shifted to single antiplatelet therapy. Despite an initial worsening of clinical severity and an extensive ischemic lesion in both patients, neurologic function improved over time, eventually allowing recovery of unaided gait. Therefore, in the absence of signs of hemorrhage, intravenous thrombolysis or dual antiplatelet regimens could be considered in strokes related to middle cerebral artery dissection.

Transcranial Doppler analysis based on computer and artificial intelligence for acute cerebrovascular disease

Cerebrovascular disease refers to damage to brain tissue caused by impaired intracranial blood circulation. It usually presents clinically as an acute nonfatal event and is characterized by high morbidity, disability, and mortality. Transcranial Doppler (TCD) ultrasonography is a non-invasive method for the diagnosis of cerebrovascular disease that uses the Doppler effect to detect the hemodynamic and physiological parameters of the major intracranial basilar arteries. It can provide important hemodynamic information that cannot be measured by other diagnostic imaging techniques for cerebrovascular disease. And the result parameters of TCD ultrasonography such as blood flow velocity and beat index can reflect the type of cerebrovascular disease and serve as a basis to assist physicians in the treatment of cerebrovascular diseases. Artificial intelligence (AI) is a branch of computer science which is used in a wide range of applications in agriculture, communications, medicine, finance, and other fields. In recent years, there are much research devoted to the application of AI to TCD. The review and summary of related technologies is an important work to promote the development of this field, which can provide an intuitive technical summary for future researchers. In this paper, we first review the development, principles, and applications of TCD ultrasonography and other related knowledge, and briefly introduce the development of AI in the field of medicine and emergency medicine. Finally, we summarize in detail the applications and advantages of AI technology in TCD ultrasonography including the establishment of an examination system combining brain computer interface (BCI) and TCD ultrasonography, the classification and noise cancellation of TCD ultrasonography signals using AI algorithms, and the use of intelligent robots to assist physicians in TCD ultrasonography and discuss the prospects for the development of AI in TCD ultrasonography.

Study on Model Iterative Reconstruction Algorithm vs. Filter Back Projection Algorithm for Diagnosis of Acute Cerebral Infarction Using CT Images

The aim was to explore the application value of computed tomography (CT) perfusion (CTP) imaging based on the iterative model reconstruction (IMR) in the diagnosis of acute cerebral infarction (ACI). 80 patients with ACI, admitted to hospital, were selected as the research objects and divided randomly into a routine treatment group (group A) and a low-dose group (group B) (each group with 40 patients). Patients in group A were scanned at 80 kV–150 mAs, and the traditional filtered back projection (FBP) algorithm was employed to reconstruct the images; besides, 80 kV–30 mAs was adopted to scan the patients in group B, and the images were reconstructed by IMR1, IMR2, IMR3, iDose4 (a kind of hybrid iterative reconstruction technology), and FBP, respectively. The application values of different algorithms were evaluated by CTP based on the collected CTP images of patients and detecting indicators. The results showed that the gray and white matter CT value, SD value, SNR, CNR, and subjective image scores of patients in group B were basically consistent with those of group A (p > 0.05) after the IMR1 reconstruction, and the CT and SD of gray and white matter in patients from group B reduced steeply (p < 0.05), while SNR and CNR increased dramatically after IMR2 and IMR3 reconstruction in contrast to group A (p < 0.05). Furthermore, the cerebral blood volume (CBV), cerebral blood flow (CBF), mean transit time (MTT) of contrast agent, and time to peak (TTP) of contrast agent in patients from group B after iDose4 and IMR reconstruction were basically the same as those of group A (p > 0.05). Therefore, IMR combined with low-dose CTP could obtain high-quality CTP images of the brain with stable perfusion indicators and low radiation dose, which could be clinically applied in the diagnosis of ACI.

Transcranial Doppler Ultrasonography in Pre-hospital Management of Stroke: Can it make a Difference?

The aim of this paper is to discuss the use of transcranial doppler in the pre-hospital management of stroke. In the pre-hospital organization, neurological defect scales are used, but they are often indicative of the occlusions of anterior circulation and not of the posterior circulation. Patients with posterior circulation stroke are sometimes not diagnosed and clinically treated. In the pre-hospital phase, the transcranial doppler may identify an occlusion of the large cerebral vessels and be useful for stroke patients, in particular those with posterior occlusions, for a more precise diagnosis and consequently for adequate treatment in the excellence centers for stroke.

Application of weighting methods for presenting risk-of-bias assessments in systematic reviews of diagnostic test accuracy studies

BACKGROUND

An assessment of the validity of individual diagnostic accuracy studies in systematic reviews is necessary to guide the analysis and the interpretation of results. Such an assessment is performed for each included study and typically reported at the study level. As studies may differ in sample size and disease prevalence, with larger studies contributing more to the meta-analysis, such a study-level report does not always reflect the risk of bias in the total body of evidence. We aimed to develop improved methods of presenting the risk of bias in the available evidence on diagnostic accuracy of medical tests in systematic reviews, reflecting the relative contribution of the study to the body of evidence in the review.

METHODS

We applied alternative methods to represent evaluations with the Quality Assessment of Diagnostic Accuracy Studies tool (QUADAS-2), weighting studies according to their relative contribution to the total sample size or their relative effective sample size. We used these methods in four existing systematic reviews of diagnostic accuracy studies, including 9, 13, 22, and 32 studies, respectively.

RESULTS

The risk-of-bias summaries for each domain of the QUADAS-2 checklist changed in all four sets of studies after replacing unit weights for the studies with relative sample sizes or with the relative effective sample size. As an example, the risk of bias was high in the patient selection domain in 31% of the studies in one review, unclear in 23% and low in 46% of studies. Weighting studies according to the relative sample size changed the corresponding proportions to 4%, 4%, and 92%, respectively. The difference between the two weighting methods was small and more noticeable when the reviews included a smaller number of studies with wider range of sample size.

CONCLUSIONS

We present an alternative way of presenting the results of risk-of-bias assessments in systematic reviews of diagnostic accuracy studies. Weighting studies according to their relative sample size or their relative effective sample size can be used as more informative summaries of the risk of bias in the total body of available evidence.

SYSTEMATIC REVIEW REGISTRATIONS

Not applicable.

Challenges of acute phase neuroimaging in VA-ECMO, pitfalls and alternative imaging options

Large vessel occlusion in patients on ECMO is challenging to appreciate clinically secondary to sedation or induced paralysis, thus placing more emphasis on neurovascular imaging. However, emergent CTA and CTP are both inaccurate and unreliable in ECMO patients due to altered circuitry and interference with normal physiologic hemodynamics. In this review, the utility of DSA is discussed in evaluating the altered hemodynamics of VA-ECMO circuits and patency of major vasculature. In addition, the potential use of TCD in ECMO patients is discussed.

European Stroke Organisation (ESO) guidelines on management of transient ischaemic attack

The aim of the present European Stroke Organisation Transient Ischaemic Attack (TIA) management guideline document is to provide clinically useful evidence-based recommendations on approaches to triage, investigation and secondary prevention, particularly in the acute phase following TIA. The guidelines were prepared following the Standard Operational Procedure for a European Stroke Organisation guideline document and according to GRADE methodology. As a basic principle, we defined TIA clinically and pragmatically for generalisability as transient neurological symptoms, likely to be due to focal cerebral or ocular ischaemia, which last less than 24 hours. High risk TIA was defined based on clinical features in patients seen early after their event or having other features suggesting a high early risk of stroke (e.g. ABCD2 score of 4 or greater, or weakness or speech disturbance for greater than five minutes, or recurrent events, or significant ipsilateral large artery disease e.g. carotid stenosis, intracranial stenosis). Overall, we strongly recommend using dual antiplatelet treatment with clopidogrel and aspirin short term, in high-risk non-cardioembolic TIA patients, with an ABCD2 score of 4 or greater, as defined in randomised controlled trials (RCTs). We further recommend specialist review within 24 hours after the onset of TIA symptoms. We suggest review in a specialist TIA clinic rather than conventional outpatients, if managed in an outpatient setting. We make a recommendation to use either MRA or CTA in TIA patients for additional confirmation of large artery stenosis of 50% or greater, in order to guide further management, such as clarifying degree of carotid stenosis detected with carotid duplex ultrasound. We make a recommendation against using prediction tools (eg ABCD2 score) alone to identify high risk patients or to make triage and treatment decisions in suspected TIA patients as due to limited sensitivity of the scores, those with score value of 3 or less may include significant numbers of individual patients at risk of recurrent stroke, who require early assessment and treatment. These recommendations aim to emphasise the importance of prompt acute assessment and relevant secondary prevention. There are no data from randomised controlled trials on prediction tool use and optimal imaging strategies in suspected TIA.

Value of transcranial color-code Doppler in evaluating intracranial atherosclerotic stenosis in patients with diabetes mellitus type 2: a comparison of transcranial Doppler and computed tomography angiography

BACKGROUND

There are several imaging assessment methods for intracranial atherosclerotic stenosis (ICAS). This study investigated the most efficient method by which to diagnose ICAS in patients with diabetes mellitus.

METHODS

One hundred seven patients with type 2 diabetes mellitus were enrolled as the experimental group and 68 healthy subjects were designated as the control group. The experimental group was examined with transcranial color-code Doppler (TCCD) and transcranial Doppler (TCD). Sixty-five patients in the experimental group were diagnosed by computed tomography angiography (CTA) on a voluntary basis. The 68 subjects in the control group were examined by TCCD alone.

RESULTS

Based on TCCD examinations, the ICAS positivity rate was 71.0% (76/107) in the experimental group, which was greater than the 42.6% (29/68) in the control group (χ2 = 13.954, P＜0.001). The middle cerebral artery was most frequently affected by ICAS (χ2 = 4.684，P=0.030), with a higher incidence of moderate and severe stenosis (χ2 =4.510，P=0.034). The ICAS positivity rate was 64.6% (42/65) by TCCD, 75.4% (49/65) by CTA, and 53.8% (35/30) by TCD. There was a statistically significant difference between the TCCD and CTA (χ2=1.795, P=0.180) and between the TCD and CTA (χ2=6.594, P=0.010) positivity rates.

CONCLUSIONS

ICAS is expected to occur in patients with diabetes mellitus more often than healthy subjects, and to involve the middle cerebral artery with moderate-to-severe stenosis. The ICAS positivity rate evaluated by TCCD was lower than CTA and higher than TCD.

Asymmetric TCD Findings in Malignant MCA Infarction, Resolution after Decompressive Hemicraniectomy: A Case Report

Transcranial Doppler (TCD) is a non-invasive method for assessing cerebral hemodynamics in the acute phase of stroke. We report a case of a 33-year-old man who presented with a massive left hemispheric infarct developing into “malignant” MCA infarction. TCD was utilized to monitor intracranial hemodynamics while the clinical and neuroimaging findings were used to help us in the decision to proceed with decompressive craniectomy (DC). Pre-operatively, there was reduced mean flow velocities (MFV) of the middle cerebral artery (MCA) with increasing pulsatility index (PI) ipsilateral to the infarct. The subsequent but smaller rise in the PI in the contralateral MCA was suggestive of very high intracranial pressure (ICP) from massive brain swelling. Serial TCD examinations post-operatively showed normalization of the PI, and subsequent rise in the left MCA MFV. Clinical improvement was also noted as the TCD findings improved. The asymmetry in TCD findings can be attributed to occlusion of the MCA with subsequent spontaneous recanalisation, occlusion of the MCA with subsequent recanalisation due to the DC, or initial occlusion and subsequent pressure effects on the arterioles of the MCA due to the “malignant” edema of that hemisphere that was relieved by DC. This case illustrates the value of TCD as a useful modality in monitoring intracranial hemodynamics in acute stroke.

Transcranial Doppler and magnetic resonance angiography assessment of intracranial stenosis: An analysis of screening modalities

BACKGROUND:

Time-of-flight (TOF) magnetic resonance angiography (MRA) of the head and transcranial Doppler (TCD) are used to diagnose intracranial stenosis, an important cause of ischemic stroke. We aimed to compare TCD findings with TOF-MRA results in a population of patients with symptoms of cerebrovascular disease in whom both tests were done within a short intervening period of each other.

METHODS:

This is a retrospective, single-center study. Among adult patients referred for symptoms of cerebrovascular disease in both outpatient and inpatient settings, those who received a TCD with adequate insonation of all intracranial arteries and underwent MRA within 3 months intervals of TCD were included in this study. We evaluated the agreement between the results of these two modalities, and also assessed sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of TCD through receiver-operating characteristic (ROC) curve analysis, while MRA considered as a comparator.

RESULTS:

Among eighty included patients, 720 arteries were examined. An overall significant agreement of 96.5% was observed between TCD and MRA (Kappa = 0.377, P < 0.001). Compared to MRA, TCD had sensitivity of 42.1%, specificity of 99.6%, PPV of 72.7%, and NPV of 98.4% (ROC area: 0.708 [0.594–0.822]). TCD is specifically accurate in evaluating middle cerebral artery (MCA) (ROC area = 0.83).

CONCLUSIONS:

The high NPV of TCD in our study indicates the utility of TCD as a diagnostic test to exclude the presence of intracranial stenosis. This study supports TCD as a convenient, safe, and reproducible imaging modality applicable in the screening of intracranial stenosis, especially to evaluate MCA.

Transcranial Doppler sonography for detecting stenosis or occlusion of intracranial arteries in people with acute ischaemic stroke

BACKGROUND

An occlusion or stenosis of intracranial large arteries can be detected in the acute phase of ischaemic stroke in about 42% of patients. The approved therapies for acute ischaemic stroke are thrombolysis with intravenous recombinant tissue plasminogen activator (rt-PA), and mechanical thrombectomy; both aim to recanalise an occluded intracranial artery. The reference standard for the diagnosis of intracranial stenosis and occlusion is intra-arterial angiography (IA) and, recently, computed tomography angiography (CTA) and magnetic resonance angiography (MRA), or contrast-enhanced MRA. Transcranial Doppler (TCD) and transcranial colour Doppler (TCCD) are useful, rapid, noninvasive tools for the assessment of intracranial large arteries pathology. Due to the current lack of consensus regarding the use of TCD and TCCD in clinical practice, we systematically reviewed the literature for studies assessing the diagnostic accuracy of these techniques compared with intra-arterial IA, CTA, and MRA for the detection of intracranial stenosis and occlusion in people presenting with symptoms of ischaemic stroke.

OBJECTIVES

To assess the diagnostic accuracy of TCD and TCCD for detecting stenosis and occlusion of intracranial large arteries in people with acute ischaemic stroke.

SEARCH METHODS

We limited our searches from January 1982 onwards as the transcranial Doppler technique was only introduced into clinical practice in the 1980s. We searched MEDLINE (Ovid) (from 1982 to 2018); Embase (Ovid) (from 1982 to 2018); Database of Abstracts of Reviews of Effects (DARE); and Health Technology Assessment Database (HTA) (from 1982 to 2018). Moreover, we perused the reference lists of all retrieved articles and of previously published relevant review articles, handsearched relevant conference proceedings, searched relevant websites, and contacted experts in the field.

SELECTION CRITERIA

We included all studies comparing TCD or TCCD (index tests) with IA, CTA, MRA, or contrast-enhanced MRA (reference standards) in people with acute ischaemic stroke, where all participants underwent both the index test and the reference standard within 24 hours of symptom onset. We included prospective cohort studies and randomised studies of test comparisons. We also considered retrospective studies eligible for inclusion where the original population sample was recruited prospectively but the results were analysed retrospectively.

DATA COLLECTION AND ANALYSIS

At least two review authors independently screened the titles and abstracts identified by the search strategies, applied the inclusion criteria, extracted data, assessed methodological quality (using QUADAS-2), and investigated heterogeneity. We contacted study authors for missing data.

MAIN RESULTS

A comprehensive search of major relevant electronic databases (MEDLINE and Embase) from 1982 to 13 March 2018 yielded 13,534 articles, of which nine were deemed eligible for inclusion. The studies included a total of 493 participants. The mean age of included participants was 64.2 years (range 55.8 to 69.9 years). The proportion of men and women was similar across studies. Six studies recruited participants in Europe, one in south America, one in China, and one in Egypt. Risk of bias was high for participant selection but low for flow, timing, index and reference standard. The summary sensitivity and specificity estimates for TCD and TCCD were 95% (95% CI = 0.83 to 0.99) and 95% (95% CI = 0.90 to 0.98), respectively. Considering a prevalence of stenosis or occlusion of 42% (as reported in the literature), for every 1000 people who receive a TCD or TCCD test, stenosis or occlusion will be missed in 21 people (95% CI = 4 to 71) and 29 (95% CI = 12 to 58) will be wrongly diagnosed as harbouring an intracranial occlusion. However, there was substantial heterogeneity between studies, which was no longer evident when only occlusion of the MCA was considered, or when the analysis was limited to participants investigated within six hours. The performance of either TCD or TCCD in ruling in and ruling out a MCA occlusion was good. Limitations of this review were the small number of identified studies and the lack of data on the use of ultrasound contrast medium.

AUTHORS' CONCLUSIONS

This review provides evidence that TCD or TCCD, administered by professionals with adequate experience and skills, can provide useful diagnostic information for detecting stenosis or occlusion of intracranial vessels in people with acute ischaemic stroke, or guide the request for more invasive vascular neuroimaging, especially where CT or MR-based vascular imaging are not immediately available. More studies are needed to confirm or refute the results of this review in a larger sample of stroke patients, to verify the role of contrast medium and to evaluate the clinical advantage of the use of ultrasound.