Henk A Marquering

Academisch Medisch Centrum Universiteit van Amsterdam | AMC · Department of Radiology and Nuclear Medicine / Department of Biomedical Engineering and Physics

The development of in silico trials based on high-fidelity simulations of clinical procedures requires the availability of large cohorts of three-dimensional (3D) patient-specific anatomy models, which are often hard to collect due to limited availability and/or accessibility and imaging quality. Statistical shape modeling (SSM) allows one to ident...

Objectives: We aimed to evaluate the real-world variation in CT perfusion (CTP) imaging protocols among stroke centers and to explore the potential for standardizing vendor software to harmonize CTP images. Methods: Stroke centers participating in a nationwide multicenter healthcare evaluation were requested to share their CTP scan and processin...

Dry electrode electroencephalography (EEG) has the potential to diagnose ischemic stroke in the acute phase. In the current study we determined the correlation between EEG spectral power and ischemic stroke size and location as determined by computed tomography perfusion (CTP). Dry electrode EEG recordings were performed in patients with acute isch...

Background: Various mortality prediction models for Transcatheter Aortic Valve Implantation (TAVI) have been developed in the past years. The effect of time on the performance of such models, however, is unclear given the improvements in the procedure and changes in patient selection, potentially jeopardizing the usefulness of the prediction model...

Citation: Koopman, M.S.; Hoving, J.W.; Tolhuisen, M.L.; Jin, P.; Thiele, F.O.; Bremer-van der Heiden, L.; van Voorst, H.; Berkhemer, O.A.; Coutinho, J.M.; Beenen, L.F.M.; et al. Accuracy of Four Different CT Perfusion Thresholds for Ischemic Core Volume and Location Estimation Using IntelliSpace Portal. Abstract: Computed tomography perfusion (CTP)...

Background Cardiac CT acquired during the acute stroke imaging protocol is an emerging alternative to transthoracic echocardiography (TTE) to screen for sources of cardioembolism. Currently, its diagnostic accuracy to detect patent foramen ovale (PFO) is unclear. Methods This was a substudy of Mind the Heart, a prospective cohort in which consecut...

Objective: Convolutional Neural Networks (CNNs) are promising for artifact detection in electroencephalography (EEG) data, but require large amounts of data. Despite increasing use of dry electrodes for EEG data acquisition, dry electrode EEG datasets are sparse. We aim to develop an algorithm for clean versus artifact dry electrode EEG data class...

Introduction Locating a vessel occlusion is important for clinical decision support in stroke healthcare. The advent of endovascular thrombectomy beyond proximal large vessel occlusions spurs alternative approaches to locate vessel occlusions. We explore whether CT perfusion (CTP) data can help to automatically locate vessel occlusions. Methods We...

Background and purpose: Infarct evolution after endovascular treatment varies widely among patients with stroke and may be affected by baseline characteristics and procedural outcomes. Moreover, IV alteplase and endovascular treatment may influence the relationship of these factors to infarct evolution. We aimed to assess whether the infarct evolu...

Background: It remains unclear if deep-learning-based white matter lesion (DL-WML) volume can predict outcome after ischemic stroke. Purpose: We aimed to develop, validate, and evaluate DL-WML volume in NCCT as a risk factor and IVT effect modifier compared to the Fazekas scale (WML-Faz) in patients also receiving EVT in an EVT-capable center. Meth...

Introduction: Current stroke guidelines do not give uniform recommendations regarding the use of CT perfusion (CTP) for the selection of patients presenting within six hours after symptom onset for endovascular treatment (EVT). Model-based analyses can be used to estimate the potential long-term costs and health effects of CTP for patient selection...

Background: A larger thrombus in patients with acute ischemic stroke might result in more complex endovascular treatment procedures, resulting in poorer patient outcomes. Current evidence on thrombus volume and length related to procedural and functional outcomes remains contradicting. This study aimed to assess the prognostic value of thrombus vo...

Purpose: Intravenous alteplase (IVT) prior to endovascular treatment (EVT) is neither superior nor noninferior to EVT alone in acute ischemic stroke patients. We aim to assess whether the effect of IVT prior to EVT differs according to CT perfusion (CTP)-based imaging parameters. Methods: In this retrospective post hoc analysis, we included pati...

Background: Perinatal arterial ischemic stroke (PAIS) is associated with adverse neurological outcomes. Quantification of ischemic lesions and consequent brain development in newborn infants relies on labor-intensive manual assessment of brain tissues and ischemic lesions. Hence, we propose an automatic method utilizing convolutional neural networ...

Background and objective: Mechanical thrombectomy is a minimally invasive procedure that aims at removing the occluding thrombus from the vasculature of acute ischemic stroke patients. Thrombectomy success and failure can be studied using in-silico thrombectomy models. Such models require realistic modeling steps to be effective. We here present a...

Objectives The beneficial effect of endovascular thrombectomy (EVT) on clinical outcome is assumed to be caused by reduced follow-up infarct volume (FIV), which could serve as an early imaging endpoint. However, the effect of EVT on the modified Rankin Scale (mRS) was poorly explained by FIV. NIHSS at 5-7 days could be a more specific measure of th...

Introduction: Endovascular thrombectomy (EVT) for large vessel occlusion stroke of the anterior circulation (LVO-a) can only be performed in selected hospitals. A prehospital triage instrument with which paramedics can reliably identify patients with an LVO-a stroke would enable direct routing of these patients to the right hospital and would conse...

Objective: To illustrate in-depth validation of prediction models developed on multicenter data. Methods: For each hospital in a multicenter registry, we evaluated predictive performance of a 30-day mortality prediction model for transcatheter aortic valve implantation (TAVI) using the Netherlands heart registration (NHR) dataset. We measured di...

CT perfusion imaging is commonly used for infarct core quantification in acute ischemic stroke patients. The outcomes and perfusion maps of CT perfusion software, however, show many discrepancies between vendors. We aim to perform infarct core segmentation directly from CT perfusion source data using machine learning, excluding the need to use the...

Good collateral status in acute ischemic stroke patients is an important indicator for good outcomes. Perfusion imaging potentially allows for the simultaneous assessment of local perfusion and collateral status. We combined multiple CTP parameters to evaluate a CTP-based collateral score. We included 85 patients with a baseline CTP and single-phas...

Background Intravenous alteplase treatment (IVT) for acute ischemic stroke carries a risk of intracranial hemorrhage (ICH). However, reperfusion of an occluded vessel itself may contribute to the risk of ICH. We determined whether IVT and reperfusion are associated with ICH or its volume in the Multicenter Randomized Clinical trial of Endovascular...

Background Cardiac thrombi are a major risk factor for ischemic stroke, but are rarely diagnosed in the acute phase. We examined characteristics and functional outcome of patients with ischemic stroke and a concomitant cardiac thrombus detected on cardiac CT performed in the acute phase. Patients and Methods We used data from “Mind the Heart,” a p...

Radiomics in neuroimaging uses fully automatic segmentation to delineate the anatomical areas for which radiomic features are computed. However, differences among these segmentation methods affect radiomic features to an unknown extent. A scan-rescan dataset (n = 46) of T1-weighted and diffusion tensor images was used. Subjects were split into a sl...

The presence of collaterals and high thrombus permeability are associated with good functional outcomes after an acute ischaemic stroke. We aim to understand the combined effect of the collaterals and thrombus permeability on cerebral blood flow during an acute ischaemic stroke. A cerebral blood flow model including the leptomeningeal collateral ci...

Background Endovascular thrombectomy (EVT) is the standard treatment for large vessel occlusion stroke of the anterior circulation (LVO-a stroke). Approximately half of EVT-eligible patients are initially presented to hospitals that do not offer EVT. Subsequent inter-hospital transfer delays treatment, which negatively affects patients' prognosis....

Background and Purpose Intracranial collateral capacity is conducive to imply parenchymal perfusion of affected territory after acute vessel occlusion. The Tan collateral score is commonly used to assess the intracranial collateral capacity; however, this score is coarsely grained and interobserver agreement is low, which reduces prognostic value a...

Background It has been suggested that selection of a first‐line endovascular thrombectomy device, that is, contact aspiration (CA) or stent retriever (SR) thrombectomy, could be based on thrombus type. Thrombus composition and mechanical behavior can partially be predicted with thrombus computed tomography (CT) characteristics. We aimed to assess t...

Purpose We aimed to study the association of non-contrast CT (NCCT) thrombus density with procedural and clinical outcomes in patients with acute ischemic stroke who underwent endovascular treatment (EVT). Since thrombus density is associated with thrombus location, we focused on M1 occlusions only. Methods Patients with available thin-slice (< 2....

Background and objective Computed tomography perfusion (CTP) is widely used in the evaluation of acute ischemic stroke patients for endovascular thrombectomy (EVT). The stability of CTP core estimation is suboptimal and varies between software packages. We aimed to quantify the volumetric and spatial agreement between the CTP ischemic core and foll...

Background: Thrombus radiomics (TR) describe complex shape and textural thrombus imaging features. We aimed to study the relationship of TR extracted from non-contrast CT with procedural and functional outcome in endovascular-treated patients with acute ischemic stroke. Methods: Thrombi were segmented on thin-slice non-contrast CT (≤1 mm) from 6...

Background The effects of thrombus imaging characteristics on procedural and clinical outcomes after ischemic stroke are increasingly being studied. These thrombus characteristics – for eg, size, location, and density – are commonly analyzed as separate entities. However, it is known that some of these thrombus characteristics are strongly related....

Purpose Onset to imaging (OTI) time is a crucial factor in determining treatment eligibility for acute ischemic stroke patients, since the treatments are time-dependent. Patients with an unknown OTI time are often excluded from treatment, or advanced imaging is needed, which is not widely and readily available. As non-contrast CT (NCCT) is part of...

Objectives Patient-tailored contrast delivery protocols strongly reduce the total iodine load and in general improve image quality in CT coronary angiography (CTCA). We aim to use machine learning to predict cases with insufficient contrast enhancement and to identify parameters with the highest predictive value. Methods Machine learning models we...

Thrombus volume in posterior circulation stroke (PCS) has been associated with outcome, through recanalization. Manual thrombus segmentation is impractical for large scale analysis of image characteristics. Hence, in this study we develop the first automatic method for thrombus localization and segmentation on CT in patients with PCS. In this multi...

BACKGROUND Acute stroke care demands fast procedures carried out through the collaboration of multiple professionals across multiple organisations. Cloud computing and the wide adoption of electronic medical records (EMR) enable healthcare systems to improve data availability and facilitate sharing among professionals. However, designing a secure a...

Background Acute stroke care demands fast procedures performed through the collaboration of multiple professionals across multiple organizations. Cloud computing and the wide adoption of electronic medical records (EMRs) enable health care systems to improve data availability and facilitate sharing among professionals. However, designing a secure a...

Background: A DPP6 gene risk haplotype, putatively enhancing Purkinje fiber transient outward current I to , associates with familial idiopathic ventricular fibrillation (IVF). Outside this genetic disposition, no clinical risk factors nor ECG features for IVF have so far been identified to recognize those at risk for IVF. Objective: We aimed to de...

Background: A DPP6 gene risk haplotype, putatively enhancing Purkinje fiber transient outward current Ito, associates with familial idiopathic ventricular fibrillation (IVF). Outside this genetic disposition, no clinical risk factors nor ECG features for IVF have so far been identified to recognize those at risk for IVF. Objective: We aimed to deve...

Objectives: Thrombus computed tomography (CT) characteristics might be used to assess histopathologic thrombus composition in patients treated with endovascular thrombectomy (EVT) for acute ischemic stroke (AIS). We aimed to assess the variability in thrombus composition that could be predicted with combined thrombus CT characteristics. Methods:...

BACKGROUND Current American guidelines are uncertain regarding endovascular treatment (EVT) for patients with acute ischemic stroke with an Alberta Stroke Program Early Computed Tomography Score (ASPECTS) <6. Dutch guidelines do not specify ASPECTS‐based exclusion criteria for EVT. In this retrospective observational cohort study, we investigated o...

Introduction Computed tomography perfusion (CTP) is variably considered to assess eligibility for endovascular thrombectomy (EVT) in acute ischemic (AIS) stroke patients. Although CTP is recommended for patient selection in later (6–24 h) time window, it is currently not recommended in the earlier (0–6 h) time window and the costs and health effect...

BACKGROUND Fast and accurate detection of large vessel occlusions (LVOs) is crucial in selection of patients with acute ischemic stroke for endovascular treatment. We assessed accuracy of an automated LVO detection algorithm with LVO localization feature. METHODS Consecutive patients who underwent computed tomography angiography in 2 centers betwe...

Background Contrary to anterior circulation stroke, studies on the association between thrombus imaging characteristics and outcomes are scarce in patients with posterior circulation stroke (PCS). We aimed to investigate the association of thrombus imaging characteristics with reperfusion and functional outcome in patients with PCS who underwent en...

Background Prehospital detection of large vessel occlusion stroke of the anterior circulation (LVO-a) would enable direct transportation of these patients to an endovascular thrombectomy (EVT) capable hospital. The ongoing ELECTRA-STROKE study investigates the diagnostic accuracy of dry electrode electroencephalography (EEG) for LVO-a stroke in the...

Background Accurate prediction of clinical outcome is of utmost importance for choices regarding the endovascular treatment (EVT) of acute stroke. Recent studies on the prediction modeling for stroke focused mostly on clinical characteristics and radiological scores available at baseline. Radiological images are composed of millions of voxels, and...

Objectives: To compare single parameter thresholding with multivariable probabilistic classification of ischemic stroke regions in the analysis of computed tomography perfusion (CTP) parameter maps. Methods: Patients were included from two multicenter trials and were divided into two groups based on their modified arterial occlusive lesion grade...

Background A thrombus in the M1 segment of the middle cerebral artery (MCA) can occlude this main stem only or extend into the M1-M2 bifurcation. The occlusion pattern may affect endovascular treatment (EVT) success, as a bifurcated thrombus may be more prone to fragmentation during retrieval. Objective To investigate whether bifurcated thrombus p...

Purpose Follow-up infarct volume (FIV) is moderately associated with functional outcome. We hypothesized that accounting for infarct location would strengthen the association of FIV with functional outcome. Methods We included 252 patients from the HERMES collaboration with follow-up diffusion weighted imaging. Patients received endovascular treat...

Introduction: Vascular anatomy might affect endovascular treatment success in acute ischemic stroke patients with large vessel occlusion. We investigated the prognostic value of extracranial vascular characteristics on procedural time and revascularization success in patients with large vessel occlusion in the anterior cerebral circulation. Patie...

Background: Cardiac thrombi are a major risk factor for ischemic stroke. We used cardiac CT to assess the prevalence of cardiac thrombi in acute ischemic stroke patients. Methods: This was a substudy of Mind the Heart, a prospective single-center cohort study in which consecutive adult patients with acute ischemic stroke underwent prospective ECG-g...

Background: In patients with ischemic stroke undergoing endovascular treatment (EVT), time to treatment and collateral status are important prognostic factors. We assessed the relation between time to CT angiography (CTA) and collateral status. Furthermore, we assessed whether collateral status modifies the relationship between onset to recanalizat...

Summary Purpose : Mechanical thrombectomies (MT) in patients with large vessel occlusion (LVO) related to calcified cerebral embolus (CCE) have been reported, through small case series, being associated with low reperfusion rate and worse outcome, compared to regular MT. The purpose of the MASC (Mechanical Thrombectomy in Acute Ischemic Stroke Rela...

Background Higher expanded Treatment In Cerebral Ischemia (eTICI) reperfusion scores after endovascular treatment (EVT) are associated with better outcomes. However, the influence of the number of passes on this association is unclear. We aimed to compare outcomes of single-pass good reperfusion (eTICI 2B) with multiple-pass excellent/complete repe...

Background: A considerable proportion of acute ischemic stroke patients treated with endovascular thrombectomy (EVT) are dead or severely disabled at 3 months despite successful reperfusion. Ischemic core imaging biomarkers may help to identify patients who are more likely to have a poor outcome after endovascular thrombectomy (EVT) despite success...

Development of in silico models of patient-specific cerebral artery networks presents several significant technical challenges: (i) The resolution and smoothness of medical CT images are much lower than the required element/cell length for FEA/CFD/FSI models; (ii) contact between vessels, and indeed self contact of high tortuosity vessel segments a...

Background: Machine learning models have been developed for numerous medical prognostic purposes. These models are commonly developed using data from single centers or regional registries. Including data from multiple centers improves robustness and accuracy of prognostic models. However, data sharing between multiple centers is complex, mainly bec...

Background and objectives: Transfer learning is a valuable approach to perform medical image segmentation in settings with limited cases available for training convolutional neural networks (CNN). Both the source task and the source domain influence transfer learning performance on a given target medical image segmentation task. This study aims to...

Objective: For accurate risk assessment of unruptured intracranial aneurysms, it is important to understand the underlying mechanisms that lead to rupture. It is known that hemodynamic anomalies contribute to aneurysm growth and rupture, and that growing aneurysms carry higher rupture risks. However, it is unknown how growth affects hemodynamic ch...

Background and Purpose Endovascular treatment for acute ischemic stroke has been proven clinically effective, but evidence of the cost-effectiveness based on real-world data is scarce. The aim of this study was to assess whether endovascular therapy plus usual care is cost-effective in comparison to usual care alone in acute ischemic stroke patient...

Background and Purpose Blinded outcome assessment in trials with prospective randomized open blinded end point design is challenging. Unblinding can result in misclassified outcomes and biased treatment effect estimates. An outcome adjudication committee assures blinded outcome assessment, but the added value for trials with prospective randomized...

Thrombus composition and mechanical properties significantly impact the procedural ease and outcomes of thrombectomy procedures in patients with acute ischemic stroke. A wide variation exists in the histological properties of thrombi between patients. If a relationship can be determined between the histological composition of a thrombus and its mec...