New Endovascular Method for Transvascular Exit of Arteries and Veins: Developed in Simulator, in Rat and in Rabbit with Full Clinical Integration

BACKGROUND: Endovascular technique has benefits vis-a-vis surgical access to organs with less accessible anatomical locations. To minimize surgical risk we propose a novel endovascular technique, to create parenchymal access through endovascular methods. METHODOLOGY/PRINCIPAL FINDINGS: We have developed, manufactured and tested an endovascular catheter with a depth limiting collar and a penetrating tip that is used to perforate vessels, thereby creating a working channel to the extra-vascular space. Computer simulations and subsequent interventions have been performed ex vivo and in vivo in both small and large animals by testing different prototypes. All tests were designed for testing extravascular hemostasis and absence of thrombo-embolic complications when exiting the vessels from the inside to the extra vascular space. We have deposited prototypes after intervention in vascular walls over a period of 14 days in rat with no impairment on blood flow and no signs of thrombo-embolic complications upon re-exploration (n = 7). We have also incorporated the catheter system with clinically available systems both in an ex vivo simulator setting and in a full scale clinical angiographical setting in rabbit were no bleeding (0%) in any of the interventions performed (n = 40). To prevent hemorrhage during termination of the procedure, a hollow electrolysis detachment-zone leaves the distal tip in the vessel-wall after the intervention. This has also been tested with absolute hemostasis in large animals (n = 6). CONCLUSIONS/SIGNIFICANCE: We have developed and tested a new system for transvascular tissue access in simulations, ex vivo and in vivo in small and large animals, integrating it with standard clinical catheters and angiographical environment, with absolute hemostasis and without thromboembolic complications. In a clinical setting for stem cell transplantation, local substance administration or tissue sampling, the benefit should be greatest in organs that are difficult or high-risk to access with other techniques, such as the pancreas, the central nervous system (CNS) and the heart

Mechanical thrombectomy in acute ischemic stroke—experience from 6 years of practice

INTRODUCTION: We present our results from the first 6 years with mechanical thrombectomy in the treatment of ischemic stroke. METHODS: Every patient treated with mechanical thrombectomy for acute ischemic stroke from September 2005 to December 2011 was consecutively included in this retrospective analysis. Baseline and outcome data were retrieved from computerized records at the hospital. National Institute of Health Stroke Scale (NIHSS) score and the modified Rankin Scale (mRS) score were used as outcome parameters. Favorable outcome was defined as a mRS score of 0–2, corresponding to independence in activities of daily living. We also evaluated revascularization and severe adverse events, with focus on symptomatic intracranial hemorrhage. RESULTS: Good functional outcome (mRS 0–2) was achieved in 50 % (120/240) of all patients. For patients with no neurological deficit prior to stroke onset (i.e., mRS = 0 before stroke), the proportion with good functional outcome was 54 %. Symptomatic hemorrhages occurred in 4.6 % of the cases (5.7 % in the anterior circulation). CONCLUSION: In summary, our results supports that mechanical thrombectomy is a safe and effective method to restore blood flow in selected patients suffering from an acute ischemic stroke

Image denoising in photon-counting CT using PFGM++ with hijacked regularized sampling

Deep learning (DL) has proven to be an important tool for high quality image denoising in low-dose and photon-counting CT. However, DL models are usually trained using supervised methods, requiring paired data that may be difficult to obtain in practice. Physics-inspired generative models, such as score-based diffusion models, offer unsupervised means of solving a wide range of inverse problems via posterior sampling. The latest in this family are Poisson flow generative models (PFGM)++ which, inspired by electrostatics, treat the $N$-dimensional data as positive electric charges in a $N+D$-dimensional augmented space. The electric field lines generated by these charges are used to find an invertible mapping, via an ordinary differential equation, between an easy-to-sample prior and the data distribution of interest. In this work, we propose a method for CT image denoising based on PFGM++ that does not require paired training data. To achieve this, we adapt PFGM++ for solving inverse problems via posterior sampling, by hijacking and regularizing the sampling process. Our method incorporates score-based diffusion models (EDM) as a special case as $D\rightarrow \infty$, but additionally allows trading off robustness for rigidity by varying $D$. The network is efficiently trained on randomly extracted patches from clinical normal-dose CT images. The proposed method demonstrates promising performance on clinical low-dose CT images and clinical images from a prototype photon-counting system

PPFM: Image denoising in photon-counting CT using single-step posterior sampling Poisson flow generative models

Diffusion and Poisson flow models have shown impressive performance in a wide range of generative tasks, including low-dose CT image denoising. However, one limitation in general, and for clinical applications in particular, is slow sampling. Due to their iterative nature, the number of function evaluations (NFE) required is usually on the order of $10-10^3$, both for conditional and unconditional generation. In this paper, we present posterior sampling Poisson flow generative models (PPFM), a novel image denoising technique for low-dose and photon-counting CT that produces excellent image quality whilst keeping NFE=1. Updating the training and sampling processes of Poisson flow generative models (PFGM)++, we learn a conditional generator which defines a trajectory between the prior noise distribution and the posterior distribution of interest. We additionally hijack and regularize the sampling process to achieve NFE=1. Our results shed light on the benefits of the PFGM++ framework compared to diffusion models. In addition, PPFM is shown to perform favorably compared to current state-of-the-art diffusion-style models with NFE=1, consistency models, as well as popular deep learning and non-deep learning-based image denoising techniques, on clinical low-dose CT images and clinical images from a prototype photon-counting CT system

Predictors for cerebral edema in acute ischemic stroke treated with intravenous thrombolysis

Cerebral edema (CED) is a severe complication of acute ischemic stroke. There is uncertainty regarding the predictors for the development of CED after cerebral infarction. We aimed to determine which baseline clinical and radiological parameters predict development of CED in patients treated with intravenous thrombolysis. We used an image-based classification of CED with 3 degrees of severity (less severe CED 1 and most severe CED 3) on postintravenous thrombolysis imaging scans. We extracted data from 42 187 patients recorded in the SITS International Register (Safe Implementation of Treatments in Stroke) during 2002 to 2011. We did univariate comparisons of baseline data between patients with or without CED. We used backward logistic regression to select a set of predictors for each CED severity. CED was detected in 9579/42 187 patients (22.7%: 12.5% CED 1, 4.9% CED 2, 5.3% CED 3). In patients with CED versus no CED, the baseline National Institutes of Health Stroke Scale score was higher (17 versus 10; P<0.001), signs of acute infarct was more common (27.9% versus 19.2%; P<0.001), hyperdense artery sign was more common (37.6% versus 14.6%; P<0.001), and blood glucose was higher (6.8 versus 6.4 mmol/L; P<0.001). Baseline National Institutes of Health Stroke Scale, hyperdense artery sign, blood glucose, impaired consciousness, and signs of acute infarct on imaging were independent predictors for all edema types. The most important baseline predictors for early CED are National Institutes of Health Stroke Scale, hyperdense artery sign, higher blood glucose, decreased level of consciousness, and signs of infarct at baseline. The findings can be used to improve selection and monitoring of patients for drug or surgical treatment

Carotid Endarterectomy After Intracranial Endovascular Thrombectomy for Acute Ischaemic Stroke in Patients with Carotid Artery Stenosis

Objective: Recent randomised controlled trials demonstrated the benefit of intracranial endovascular thrombectomy (EVT) in acute ischaemic stroke. There is no consensus, however, on how to treat concomitant extracranial carotid artery stenosis after EVT. The aim of this study was to evaluate the outcome in patients treated with carotid endarterectomy (CEA) after EVT, comparing complication rates among patients undergoing CEA for stroke without previous EVT. Methods: This was a registry study of all patients (n = 3 780) treated with CEA after stroke in Sweden and the capital Helsinki region, Finland, from January 2011 to September 2020. Sixty three patients (1.7%; 0.5% 2011, 4.3% 2019) underwent EVT prior to CEA. The primary outcome was 30 day stroke and death rate. Results: The EVT+CEA group had major stroke as the qualifying neurological event (QNE) in 79%, but just 5.9% had this in the CEA only group (p < .001). Intravenous thrombolysis was administered before EVT in 54% of patients in the EVT+CEA group, but in just 12% in those receiving CEA only (p < .001). The combined stroke and death rate at 30 days for EVT+CEA was 0.0% (95% confidence interval [CI] 0.0 - 5.7). One patient had a post-operative TIA, none had post-operative intracerebral or surgical site haemorrhage. CEA was performed within a median of seven days (interquartile range 4, 15) after QNE, and 75% had CEA Conclusion: These results indicate that CEA is safe to perform after previous successful EVT for acute ischaemic stroke. Results were comparable with those undergoing CEA only, despite the EVT+CEA patients having more severe stroke symptoms prior to surgery, and timing was similar.Peer reviewe

Mechanical thrombectomy in acute ischemic stroke : Consensus statement by ESO-Karolinska Stroke Update 2014/2015, supported by ESO, ESMINT, ESNR and EAN

The original version of this consensus statement on mechanical thrombectomy was approved at the European Stroke Organisation (ESO)-Karolinska Stroke Update conference in Stockholm, 16-18 November 2014. The statement has later, during 2015, been updated with new clinical trials data in accordance with a decision made at the conference. Revisions have been made at a face-to-face meeting during the ESO Winter School in Berne in February, through email exchanges and the final version has then been approved by each society. The recommendations are identical to the original version with evidence level upgraded by 20 February 2015 and confirmed by 15 May 2015. The purpose of the ESO-Karolinska Stroke Update meetings is to provide updates on recent stroke therapy research and to discuss how the results may be implemented into clinical routine. Selected topics are discussed at consensus sessions, for which a consensus statement is prepared and discussed by the participants at the meeting. The statements are advisory to the ESO guidelines committee. This consensus statement includes recommendations on mechanical thrombectomy after acute stroke. The statement is supported by ESO, European Society of Minimally Invasive Neurological Therapy (ESMINT), European Society of Neuroradiology (ESNR), and European Academy of Neurology (EAN).Peer reviewe