BackgroundBenefit of thrombectomy in patients with a low initial Alberta Stroke Program Early CT Score (ASPECTS) is still uncertain. We hypothesized that, despite low ASPECTS, patients may benefit from endovascular recanalization if good collaterals are present.MethodsIschemic stroke patients with large vessel occlusion in the anterior circulation and an ASPECTS of ≤5 were analyzed. Collateral status (CS) was assessed using a 5-point-scoring system in CT angiography with poor CS defined as CS=0–1. Clinical outcome was determined using the modified Rankin Scale (mRS) score after 90 days. Edema formation was measured in admission and follow-up CT by net water uptake.Results27/100 (27%) patients exhibited a CS of 2–4. 50 patients underwent successful vessel recanalization and 50 patients had a persistent vessel occlusion. In multivariable logistic regression analysis, collateral status (OR 3.0; p=0.003) and vessel recanalization (OR 12.2; p=0.009) significantly increased the likelihood of a good outcome (mRS 0–3). A 1-point increase in CS was associated with 1.9% (95% CI 0.2% to 3.7%) lowered lesion water uptake in follow-up CT .ConclusionEndovascular recanalization in patients with ASPECTS of ≤5 but good collaterals was linked to improved clinical outcome and attenuated edema formation. Collateral status may serve as selection criterion for thrombectomy in low ASPECTS patients.

Cerebrovascular diseases, in particular ischemic stroke, are one of the leading global causes of death in developed countries. Perfusion CT and/or MRI are ideal imaging modalities for characterizing affected ischemic tissue in the hyper-acute phase. If infarct growth over time could be predicted accurately from functional acute imaging protocols together with advanced machine-learning based image analysis, the expected benefits of treatment options could be better weighted against potential risks. The quality of the outcome prediction by convolutional neural networks (CNNs) is so far limited, which indicates that even highly complex deep learning algorithms are not fully capable of directly learning physiological principles of tissue salvation through weak supervision due to a lack of data (e.g., follow-up segmentation). In this work, we address these current shortcomings by explicitly taking into account clinical expert knowledge in the form of segmentations of the core and its surrounding penumbra in acute CT perfusion images (CTP), that are trained to be represented in a low-dimensional non-linear shape space. Employing a multi-scale CNN (U-Net) together with a convolutional auto-encoder, we predict lesion tissue probabilities for new patients. The predictions are physiologically constrained to a shape embedding that encodes a continuous progression between the core and penumbra extents. The comparison to a simple interpolation in the original voxel space and an unconstrained CNN shows that the use of such a shape space can be advantageous to predict time-dependent growth of stroke lesions on acute perfusion data, yielding a Dice score overlap of 0.46 for predictions from expert segmentations of core and penumbra. Our interpolation method models monotone infarct growth robustly on a linear time scale to automatically predict clinically plausible tissue outcomes that may serve as a basis for more clinical measures such as the expected lesion volume increase and can support the decision making on treatment options and triage.

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Objective In cases of spontaneous subarachnoid hemorrhage (sSAH) and symptomatic cerebral vasospasm (sCVS), multiple intra-arterial treatments (IATs) can be potentially useful for the functional outcome, even if the prognosis is initially poor. But the actual influence of the number of IATs has yet to be clarified. We wanted to assess if there are differences in the functional outcome between patients with a singular IAT and multiple IATs for sCVS after sSAH. Methods In a single-center study, 405 consecutive patients with nontraumatic SAH were analyzed retrospectively. A total of 126 developed sCVS, and 86 received IAT (32 singular and 54 multiple, i.e., more than one) with nimodipine with or without percutaneous transluminal angioplasty (PTA). Both groups were compared for demographic data, initial treatment (clipping or endovascular), and initial grading (World Federation of Neurosurgical Societies/Fisher classification, intraventricular hemorrhage, and intracerebral hemorrhage). The modified Rankin Scale (mRS) was used to assess functional outcome at the time of discharge and after 3 and 6 months. The development of CVS-associated infarction was assessed by computed tomography (CT). Categorical variables of the patient groups were analyzed in contingency tables using the Fisher exact test, chi-square test, and the Mann-Whitney U test. Statistical significance was accepted at p < 0.05. Results Patient groups with singular and multiple IATs were comparable concerning demographic data and initial grading. At the end of follow-up after 6 months, both groups showed comparable functional outcomes. A favorable outcome (mRS: 0–3) was observed in 14 of 26 patients (53.9%) with a single IAT and for 29 of 49 patients (59.2%) with multiple IATs. An unfavorable outcome (mRS: 4–6) occurred in 12 of 26 patients (46.1%) with a single IAT and for 20 of 49 patients (40.8%) with multiple IATs (p = 0.420). In the group with a single IAT, 22 of 32 patients (68.8%) developed CVS-associated infarction; 32 of 54 patients (59.3%) showed brain infarcts after multiple IATs (p = 0.259). Conclusion For patients with sCVS after sSAH, multiple IATs (nimodipine with or without additional PTA) can be applied safely because no significant differences in functional outcome were observed compared with a singular IAT. We conclude that patients should be treated repeatedly if vasospasm reoccurs.

The aim of this study was to investigate the accuracy of bone mineral density (BMD) determined by quantitative computed tomography (qCT) based on in situ and ex situ scans of cadavers of variable stature. The in uence of surrounding tissue on the quanti cation of CT images of ex situ scanned femora was investigated in air and in water and compared with the in situ scanned femora. The study showed that the surrounding tissue has an impact on the grey value-based representation of the scanned object as well as on the calibration of BMD, in uencing the determination of BMD. Local di erences in BMD of up to 17.5% were observed, which might originate from beam hardening artifacts.