A deep learning method to identify and localize large-vessel occlusions from cerebral digital subtraction angiography.

BACKGROUND AND PURPOSE: An essential step during endovascular thrombectomy is identifying the occluded arterial vessel on a cerebral digital subtraction angiogram (DSA). We developed an algorithm that can detect and localize the position of occlusions in cerebral DSA. METHODS: We retrospectively collected cerebral DSAs from a single institution between 2018 and 2020 from 188 patients, 86 of whom suffered occlusions of the M1 and proximal M2 segments. We trained an ensemble of deep-learning models on fewer than 60 large-vessel occlusion (LVO)-positive patients. We evaluated the model on an independent test set and evaluated the truth of its predicted localizations using Intersection over Union and expert review. RESULTS: On an independent test set of 166 cerebral DSA frames with an LVO prevalence of 0.19, the model achieved a specificity of 0.95 (95% confidence interval [CI]: 0.90, 0.99), a precision of 0.7450 (95% CI: 0.64, 0.88), and a sensitivity of 0.76 (95% CI: 0.66, 0.91). The model correctly localized the LVO in at least one frame in 13 of the 14 LVO-positive patients in the test set. The model achieved a precision of 0.67 (95% CI: 0.52, 0.79), recall of 0.69 (95% CI: 0.46, 0.81), and a mean average precision of 0.75 (95% CI: 0.56, 0.91). CONCLUSION: This work demonstrates that a deep learning strategy using a limited dataset can generate effective representations used to identify LVOs. Generating an expanded and more complete dataset of LVOs with obstructed LVOs is likely the best way to improve the model's ability to localize LVOs.

Dataset on permeability of wings from owls and non-silently flying birds.

The very soft and flow-permeable plumage is among the special adaptations of the owl that the silent flight is attributed to. Using a specially designed apparatus that provides a low-speed volume flow of air through a small sample of porous material, measurements of the air flow permeability were performed in accordance to ISO 9053 on a total of 39 prepared wing specimen from six different bird species, including three species of silently flying owls and three non-silently flying bird species. The resulting data set described in the present paper contains the static airflow resistance measured at different positions on the wing.

Using an artificial intelligence software improves emergency medicine physician intracranial haemorrhage detection to radiologist levels.

BACKGROUND: Tools to increase the turnaround speed and accuracy of imaging reports could positively influence ED logistics. The Caire ICH is an artificial intelligence (AI) software developed for ED physicians to recognise intracranial haemorrhages (ICHs) on non-contrast enhanced cranial CT scans to manage the clinical care of these patients in a timelier fashion. METHODS: A dataset of 532 non-contrast cranial CT scans was reviewed by five board-certified emergency physicians (EPs) with an average of 14.8 years of practice experience. The scans were labelled in random order for the presence or absence of an ICH. If an ICH was detected, the reader further labelled all subtypes present (ie, epidural, subdural, subarachnoid, intraparenchymal and/or intraventricular haemorrhage). After a washout period, the five EPs reviewed again the scans individually with the assistance of Caire ICH. The mean accuracy of the EP readings with AI assistance was compared with the mean accuracy of three general radiologists reading the films individually. The final diagnosis (ie, ground truth) was adjudicated by a consensus of the radiologists after their individual readings. RESULTS: Mean EP reader accuracy significantly increased by 6.20% (95% CI for the difference 5.10%-7.29%; p=0.0092) when using Caire ICH to detect an ICH. Mean accuracy of the EP cohort in detecting an ICH using Caire ICH was found to be more accurate than the radiologist cohort prior to discussion; this difference, however, was not statistically significant. CONCLUSION: The Caire ICH software significantly improved the accuracy and sensitivity of detecting an ICH by the EP to a level comparable to general radiologists. Further prospective research with larger numbers will be needed to understand the impact of Caire ICH on ED logistics and patient outcomes.

Mechanical Venous Thrombectomy Using Indigo Aspiration System: A Case Report.

We present a case of successful endovascular thrombectomy of cerebral venous sinus thrombosis utilizing Penumbra's Indigo Aspiration System (Penumbra Inc., Place Alameda, CA), a minimally invasive system with a large-lumen (Indigo System CAT7, 7F) catheter predominantly used for the removal of thromboembolism involving the peripheral arterial and venous systems. A 30-year-old female presented with a seizure and focal neurological deficits and was found to have a left posterior temporal lobe hemorrhagic infarct secondary to an extensive cerebral venous sinus thrombosis extending from the left transverse sinus to the ipsilateral internal jugular bulb. We considered the combination of seizure, motor deficit, and hemorrhagic infarct high-risk features for poor response to standard medical therapy with therapeutic anticoagulation. Therefore, we performed a mechanical venous thrombectomy with the above device in addition to anticoagulation treatment with heparin infusion. This combination therapy resulted in a technically successful radiographic recanalization of the involved sinuses and an excellent functional outcome at follow-up. This case demonstrates that this trackable, atraumatic, large-bore system was safe and efficacious in the cerebral venous system, permitting near-complete thrombus removal.

External Validation of an Artificial Intelligence Device for Intracranial Hemorrhage Detection.

BACKGROUND: Artificial intelligence applications have gained traction in the field of cerebrovascular disease by assisting in the triage, classification, and prognostication of both ischemic and hemorrhagic stroke. The Caire ICH system aims to be the first device to move into the realm of assisted diagnosis for intracranial hemorrhage (ICH) and its subtypes. METHODS: A single-center retrospective dataset of 402 head noncontrast CT scans (NCCT) with an intracranial hemorrhage were retrospectively collected from January 2012 to July 2020; an additional 108 NCCT scans with no intracranial hemorrhage findings were also included. The presence of an ICH and its subtype were determined from the International Classification of Diseases-10 code associated with the scan and validated by an expert panel. We used the Caire ICH vR1 to analyze these scans, and we evaluated its performance in terms of accuracy, sensitivity, and specificity. RESULTS: We found the Caire ICH system to have an accuracy of 98.05% (95% confidence interval [CI]: 96.44%-99.06%), a sensitivity of 97.52% (95% CI: 95.50%-98.81%), and a specificity of 100% (95% CI: 96.67%-100.00%) in the detection of ICH. Experts reviewed the 10 incorrectly classified scans. CONCLUSIONS: The Caire ICH vR1 algorithm was highly accurate, sensitive, and specific in detecting the presence or absence of an ICH and its subtypes in NCCTs. This work suggests that the Caire ICH device has potential to minimize clinical errors in ICH diagnosis that could improve patient outcomes and current workflows as both a point-of-care tool for diagnostics and as a safety net for radiologists.

Deep Learning System Boosts Radiologist Detection of Intracranial Hemorrhage.

BACKGROUND: Intracranial hemorrhage (ICH) requires emergent medical treatment for positive outcomes. While previous artificial intelligence (AI) solutions achieved rapid diagnostics, none were shown to improve the performance of radiologists in detecting ICHs. Here, we show that the Caire ICH artificial intelligence system enhances a radiologist's ICH diagnosis performance. METHODS: A dataset of non-contrast-enhanced axial cranial computed tomography (CT) scans (n=532) were labeled for the presence or absence of an ICH. If an ICH was detected, its ICH subtype was identified. After a washout period, the three radiologists reviewed the same dataset with the assistance of the Caire ICH system. Performance was measured with respect to reader agreement, accuracy, sensitivity, and specificity when compared to the ground truth, defined as reader consensus. RESULTS: Caire ICH improved the inter-reader agreement on average by 5.76% in a dataset with an ICH prevalence of 74.3%. Further, radiologists using Caire ICH detected an average of 18 more ICHs and significantly increased their accuracy by 6.15%, their sensitivity by 4.6%, and their specificity by 10.62%. The Caire ICH system also improved the radiologist's ability to accurately identify the ICH subtypes present. CONCLUSION: The Caire ICH device significantly improves the performance of a cohort of radiologists. Such a device has the potential to be a tool that can improve patient outcomes and reduce misdiagnosis of ICH.

Predicting poor response to anti-coagulation therapy in cerebral venous thrombosis using a simple clinical-radiological score.

BACKGROUND: Multiple studies have attempted to determine predictors of poor clinical outcomes in cerebral venous thrombosis (CVT). Fewer studies target to identify predictors of poor response to anticoagulation therapy in CVT. OBJECTIVE: We aimed to determine the predictors of poor clinical response to therapeutic anticoagulation in patients with acute CVT. METHODS: We performed a retrospective analysis of patients therapeutically anticoagulated for acute CVT. We defined poor clinical outcomes as death, need for mechanical thrombectomy during the hospitalization, or a modified Rankin Scale (mRS) > 3 at clinical follow-up. Bivariate and multivariate analyses identified factors associated with poor outcomes in anticoagulated patients for acute CVT, and we used the identified factors to create the PRACT-CVT (Poor Response to Anticoagulation Therapy in CVT) score. RESULTS: We included 109 patients anticoagulated with acute CVT. The mean patient age was 37 years old (SD 19); nine patients were > 65 years, ten patients were < 10 years, and 64 (59%) were female. Twenty-one (19%) patients had poor clinical outcomes. Age > 65 or < 10 years (OR: 3.16, 95% CI: 1.06-9.44), a GCS ≤ 12 upon presentation (OR: 19.2, 95% CI: 4.05-91.4), focal motor deficits at admission (OR: 5.03, 95% CI: 1.64-15.44), clinical deterioration following admission (OR: 28.18, CI: 4.81-164.86), seizures following admission (OR: 5.59, 95% CI: 1.27-24.51), evidence of brain bleeding/ischemia on admission (OR: 4.67, 95% CI: 1.42-15.34), involvement of the superior sagittal sinus (OR: 3.88, CI: 1.33-11.32), or involvement of both transverse sinuses (OR: 3.87, 95% CI: 1.01-14.90) predicted poor clinical outcome despite therapeutic anticoagulation. A PRACT-CVT score (0-22 points) of ≥ 7 points provided a sensitivity of 71% and a specificity of 95% for predicting poor clinical outcomes with anticoagulation alone. CONCLUSION: Patients with acute CVT aged > 65 or < 10 years old, presenting with a GCS ≤ 12, with focal motor deficits, showing clinical deterioration after admission, having clinical seizures during hospitalization, with brain bleeding/ischemia on initial neuroimaging, involvement of the superior sagittal sinus, or involvement of both transverse sinuses had poor response to anticoagulation. Clinicians may employ the PRACT-CVT score to predict poor response to anticoagulation for acute CVT.

Identification of successful cerebral reperfusions (mTICI ≥2b) using an artificial intelligence strategy.

BACKGROUND: The modified thrombolysis in cerebral infarction (mTICI) scale is a widely used and validated qualitative tool to evaluate angiographic intracerebral inflow following endovascular thrombectomy (EVT). We validated a machine-learning (ML) algorithm to grade digital subtraction angiograms (DSA) using the mTICI scale. MATERIALS AND METHODS: We included angiograms of identified middle cerebral artery (MCA) occlusions who underwent EVT. The complete DSA sequences were preprocessed and normalized. We created three convolutional neural networks to classify DSA into two outcomes, low- (mTICI 0,1,2a) and high-grade (mTICI 2b,2c,3). RESULTS: We included a total of 234 angiograms in this study. The area under the receiver operating characteristic was 0.863 (95% CI 0.816-0.909), 0.914 (95% CI 0.876-0.951), and 0.890 (95% CI 0.848-0.932) for the anteroposterior (AP), lateral (L), and combined models, respectively, when dichotomizing outcomes into low and high grade. The models' area under the precision-recall curve was 0.879 (95% CI 0.829-0.930), 0.906 (95% CI 0.844-0.968), and 0.887 (95% CI 0.834-0.941) for the AP, L, and combined models. CONCLUSION: In complete cerebral DSA, our angiography-based ML strategy was able to predict mTICI scores following EVT rapidly and reliably for MCA occlusions.

Bilateral carotid dissection due to Eagle syndrome in a young female.

Eagle syndrome (ES) is a rare clinical syndrome characterized by the elongation of the temporal bone's styloid process, or calcification of stylohyoid ligament, compressing surrounding structures causing pharyngalgia. One of its variants, the styloid-carotid artery syndrome, produces symptoms by compression of the external or internal carotid arteries (ICA). Here, we present a case of a 43-year-old woman with ES and bilateral ICA dissections. The patient underwent staged bilateral angioplasty and covered stent placement, followed by styloidectomy. A computerized tomography angiogram revealed patency of both stents at a two-year follow-up.

Differential relative efficacy between drug-eluting stents in patients with bare metal and drug-eluting stent restenosis; evidence in support of drug resistance: insights from the ISAR-DESIRE and ISAR-DESIRE 2 trials.

AIMS: In drug-eluting stent (DES) restenosis, the contribution of drug hyporesponsiveness is poorly defined. We sought to evaluate if, in the setting of treatment for in-stent restenosis, the relative efficacy of sirolimus-eluting stents (SES) and of paclitaxel-eluting stents (PES) depends on the underlying substrate in which the stents are implanted, i.e., on whether the restenosis occurs within bare metal stents or within SES. METHODS AND RESULTS: We pooled data from the ISAR-DESIRE and ISAR-DESIRE 2 randomised trials and analysed outcomes in SES-treated and PES-treated patients. In all, 650 patients were included. Angiographic follow-up was available for 87% of patients. In SES-treated patients, both late loss (LL) and percentage diameter stenosis (%DS) were lower in patients treated for bare metal stent restenosis compared with SES restenosis (0.21±0.59 mm versus 0.41±0.66 mm, p=0.007; 27.6±19.4% versus 34.0±20.9%, p=0.015, respectively). In PES-treated patients, LL and %DS were similar in patients treated for bare metal stent restenosis compared with SES restenosis (0.48±0.59 mm versus 0.39±0.71, p=0.47; 33.5±22.2% versus 32.7±18.6%, p=0.75, respectively). Similarly, in terms of overall clinical efficacy, in SES-treated patients clinical outcomes were better in patients with bare metal stent restenosis compared with SES restenosis while in PES-treated patients outcomes were similar in both groups. At multivariate analyses the use of SES to treat restenosis within SES was predictive of both higher LL and %DS. CONCLUSIONS: The efficacy of sirolimus-eluting but not paclitaxel-eluting stents is significantly reduced when used for treatment of SES restenosis as compared to bare metal stent restenosis. The lower antirestenotic efficacy following SES implantation in patients with SES restenosis may support a role for drug resistance in restenosis within these stents.

Laser-heated emissive plasma probe.

Emissive probes are standard tools in laboratory plasmas for the direct determination of the plasma potential. Usually they consist of a loop of refractory wire heated by an electric current until sufficient electron emission. Recently emissive probes were used also for measuring the radial fluctuation-induced particle flux and other essential parameters of edge turbulence in magnetized toroidal hot plasmas [R. Schrittwieser et al., Plasma Phys. Controlled Fusion 50, 055004 (2008)]. We have developed and investigated various types of emissive probes, which were heated by a focused infrared laser beam. Such a probe has several advantages: higher probe temperature without evaporation or melting and thus higher emissivity and longer lifetime, no deformation of the probe in a magnetic field, no potential drop along the probe wire, and faster time response. The probes are heated by an infrared diode laser with 808 nm wavelength and an output power up to 50 W. One probe was mounted together with the lens system on a radially movable probe shaft, and radial profiles of the plasma potential and of its oscillations were measured in a linear helicon discharge.

Rapid, painless unilateral vision loss in a 37-year-old healthy woman.

A 37-year-old woman experienced painless, progressive vision loss to no light perception in the left eye over the course of 3 days. The right eye was unaffected. On examination, the only other abnormal finding was a +4 left afferent pupillary defect. She was initially diagnosed with retrobulbar optic neuritis and admitted for treatment with intravenous methylprednisolone. Neuro-imaging revealed a large right anterior cerebral artery aneurysm that crossed the midline to compress the left optic nerve. The aneurysm was treated with coil embolization, which was technically successful but which did not lead to significant improvement in vision.