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Littérature scientifique sur le sujet « Non-Contrast CT (NCCT) »
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Articles de revues sur le sujet "Non-Contrast CT (NCCT)"
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Qazi, Shakeel, Emmad Qazi, Alexis T. Wilson, Connor McDougall, Fahad Al-Ajlan, James Evans, Henrik Gensicke et al. « Identifying Thrombus on Non-Contrast CT in Patients with Acute Ischemic Stroke ». Diagnostics 11, no 10 (16 octobre 2021) : 1919. http://dx.doi.org/10.3390/diagnostics11101919.
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The hyperdense sign is a marker of thrombus in non-contrast computed tomography (NCCT) datasets. The aim of this work was to determine optimal Hounsfield unit (HU) thresholds for thrombus segmentation in thin-slice non-contrast CT (NCCT) and use these thresholds to generate 3D thrombus models. Patients with thin-slice baseline NCCT (≤2.5 mm) and MCA-M1 occlusions were included. CTA was registered to NCCT, and three regions of interest (ROIs) were placed in the NCCT, including: the thrombus, contralateral brain tissue, and contralateral patent MCA-M1 artery. Optimal HU thresholds differentiating the thrombus from non-thrombus tissue voxels were calculated using receiver operating characteristic analysis. Linear regression analysis was used to predict the optimal HU threshold for discriminating the clot only based on the average contralateral vessel HU or contralateral parenchyma HU. Three-dimensional models from 70 participants using standard (45 HU) and patient-specific thresholds were generated and compared to CTA clot characteristics. The optimal HU threshold discriminating thrombus in NCCT from other structures varied with a median of 51 (IQR: 49–55). Experts chose 3D models derived using patient-specific HU models as corresponding better to the thrombus seen in CTA in 83.8% (31/37) of cases. Patient-specific HU thresholds for segmenting the thrombus in NCCT can be derived using normal parenchyma. Thrombus segmentation using patient-specific HU thresholds is superior to conventional 45 HU thresholds.
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Saifudin, Saifudin, et Catur Budi Saputra. « NOISE REDUCTION AT IMAGE NON CONTRAST CT-SCAN UROGRAPHY WITH USING ITERATIVE RECONSTRUCTION ». SANITAS : Jurnal Teknologi dan Seni Kesehatan 12, no 1 (14 juillet 2021) : 15–20. http://dx.doi.org/10.36525/sanitas.2021.2.
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The CT Scan examination technique that in the last decade is popular in diagnosing urinary stones is NCCT Urography examination. This examination is fast and informative, but this examination has a deficiency that the resulting image has a fairly high noise. Iterative Reconstruction is a method of algorithm reconstruction on CT Scan with the basic principle of estimating data to produce reconstruction image by reducing noise. The purpose of this study was to find out the difference in noise value in the use of Iterative Reconstruction in reducing noise and improving the quality of NCCT Urography image. This research was conducted retrospectively, namely on existing image given iterative reconstruction treatment of 20%, 40%, 60%, 80% and 100%. Samples in each iterative reconstruction treatment group as many as 10 images. Image is done noise measurement by doing ROI in kidneys, ureter and VU. Data analysis is done by conducting different tests of One Way Anova using SPSS Software. The results showed that there was a significant difference in noise value after it was done Iterative Reconstruction. Noise decreased as the percentage of used Iterative Reconstruction increased in NCCT Urography image. In the use of Iterative Reconstruction percentage of 100% obtained the lowest average noise value of 9.11. The use of Iterative Reconstruction can reduce noise in NCCT Urography image by 9.386% compared to Filtered Back Projection (FBP). Iterative reconstruction is able to reduce noise and improve the image quality of NCCT Urography.
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Naylor, Jillian, Leonid Churilov, Ziyuan Chen, Miriam Koome, Neil Rane et Bruce C. V. Campbell. « Reliability, Reproducibility and Prognostic Accuracy of the Alberta Stroke Program Early CT Score on CT Perfusion and Non-Contrast CT in Hyperacute Stroke ». Cerebrovascular Diseases 44, no 3-4 (2017) : 195–202. http://dx.doi.org/10.1159/000479707.
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Background: Alberta Stroke Program Early CT Score (ASPECTS) assesses early ischemic change on non-contrast CT (NCCT). We hypothesised that assessing ASPECTS regions on CT Perfusion (CTP) rather than NCCT would improve inter-rater agreement and prognostic accuracy, particularly in patients presenting early after stroke onset. Methods: Ischemic stroke patients treated with intravenous alteplase from 2009 to 2014 at our institution were included in this study. Inter-rater agreement and prognostic accuracy of ASPECTS across modalities were analysed by the time between stroke onset and initial NCCT, dichotomized 1st quartile versus quartiles 2-4, referred to as epochs. ASPECTS was assessed by 2 independent raters, blinded to stroke onset time, with agreement determined by weighted kappa (κw). Prognostic accuracy for favourable outcome (modified Rankin Scale 0-2) was assessed using the receiver-operating characteristic analysis. Results: A total of 227 participants were included. There was significant time-by-CT modality interaction for ASPECTS, p < 0.0001. The inter-rater agreement of ASPECTS on NCCT significantly increased as onset to CT time increased (κw epoch 1 = 0.76 vs. κw epoch 2-4 = 0.89, p = 0.04), whereas agreement using CTP parameters was stable across epochs. Inter-rater agreement for CTP-ASPECTS was significantly higher than NCCT in early epoch: Tmax κw = 0.96, p = 0.002; cerebral blood volume (CBV) κw = 0.95, p = 0.003; cerebral blood flow (CBF) κw = 0.94, p = 0.006, with no differences in the later epochs. Prognostic accuracy of ASPECTS on NCCT in epoch 1 were (area under the ROC curves [AUC] = 0.52, 95% CI 0.48-0.56), CBV (AUC = 0.55, 95% CI 0.42-0.69, CBF (AUC = 0.58, 95% CI 0.46-0.71) and Tmax (AUC = 0.62, 95% CI 0.49-0.75), p = 0.46 between modalities. Conclusions: CTP can improve reliability when assessing the extent of ischemic changes, particularly in patients imaged early after stroke onset.
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Mattay, Raghav R., Lane Miner, Alexander Z. Copelan, Karapet Davtyan, James E. Schmitt, Ephraim W. Church et Alexander C. Mamourian. « Unruptured Arteriovenous Malformations in the Multidetector Computed Tomography Era : Frequency of Detection and Predictable Failures ». Journal of Clinical Imaging Science 12 (18 février 2022) : 5. http://dx.doi.org/10.25259/jcis_200_2021.
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Objectives: While hemorrhage arising from ruptured arteriovenous malformations (AVMs) is usually evident on multidetector non-contrast computed tomography (NCCT), unruptured AVMs can be below the limits of detection. We performed a retrospective review of NCCT of patients with a proven diagnosis of unruptured AVM to determine if advances in CT technology have made them more apparent and what features predict their detection. Material and Methods: Twenty-five NCCTs met inclusion criteria of having angiography or MR proven AVM without hemorrhage, prior surgery, or other CNS disease. Demographic variables, clinical symptoms at presentation, abnormal CT imaging findings, attenuation of the superior sagittal sinus (SSS), and Spetzler-Martin grade of each AVM were recorded. We examined the relationship between AVM detection and SSS attenuation through Kruskal–Wallis test. Exploratory serial logistic principal components analysis was performed including demographics, symptoms, and CT features in the multivariate model. Results: About 80% of the NCCTs showed an abnormality while 20% were normal. All those with an identifiable abnormality showed hyperdensity (80%). Logistic regression models indicate that clustered associations between several CT features, primarily calcifications, hyperdensity, and vascular prominence significantly predicted Spetzler-Martin grade (likelihood ratio 7.7, P = 0.006). SSS attenuation was significantly lower in subjects with occult AVMs when compared to those with CT abnormalities (median 47 vs. 55 HU, P < 0.04). Conclusion: Abnormal hyperdensity was evident in all detectable cases (80%) and multiple CT features were predictive of a higher Spetzler-Martin AVM grade. Moreover, SSS attenuation less than 50 HU was significantly correlated with a false-negative NCCT.
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Avsenik, Jernej, Janja Pretnar Oblak et Katarina Surlan Popovic. « Non-contrast computed tomography in the diagnosis of cerebral venous sinus thrombosis ». Radiology and Oncology 50, no 3 (1 septembre 2016) : 263–68. http://dx.doi.org/10.1515/raon-2016-0026.
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Abstract Background The aim of the study was to investigate the sensitivity and specificity of non-contrast computed tomography (NCCT) in the diagnosis of cerebral venous sinus thrombosis (CVST). Methods. Screening our neurological department database, we identified 53 patients who were admitted to neurological emergency department with clinical signs of CVST. Two independent observers assessed the NCCT scans for the presence of CVST. CT venography and/or MR venography were used as a reference standard. Interobserver agreement between the two readers was assessed using Kappa statistic. Attenuation inside the cerebral venous sinuses was measured and compared between the patient and the control group. Results CVST was confirmed in 13 patients. Sensitivity and specificity of NCCT for overall presence of CVST were 100% and 83%, respectively, with Kappa value of 0.72 (a good agreement between observers). The attenuation values between CVST patients and control group were significantly different (73.4 ± 14.12 HU vs. 58.1 ± 7.58 HU; p = 0.000). The ROC analysis showed an area under the curve (AUC) of 0.916 (95% CI, 0.827 – 1.00) and an optimal cutoff value of 64 HU, leading to a sensitivity of 85% and specificity of 87%. Conclusions NCCT as a first-line investigation has a high value for diagnosis of CVST in the emergency setting. The additional measurement of the sinus attenuation may improve the diagnostic value of the examination.
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Ma, Zhuangxuan, Liang Jin, Lukai Zhang, Yuling Yang, Yilin Tang, Pan Gao, Yingli Sun et Ming Li. « Diagnosis of Acute Aortic Syndromes on Non-Contrast CT Images with Radiomics-Based Machine Learning ». Biology 12, no 3 (21 février 2023) : 337. http://dx.doi.org/10.3390/biology12030337.
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We aimed to detect acute aortic syndromes (AAS) on non-contrast computed tomography (NCCT) images using a radiomics-based machine learning model. A total of 325 patients who underwent aortic CT angiography (CTA) were enrolled retrospectively from 2 medical centers in China to form the internal cohort (230 patients, 60 patients with AAS) and the external testing cohort (95 patients with AAS). The internal cohort was divided into the training cohort (n = 135), validation cohort (n = 49), and internal testing cohort (n = 46). The aortic mask was manually delineated on NCCT by a radiologist. Least Absolute Shrinkage and Selection Operator regression (LASSO) was used to filter out nine feature parameters; the Support Vector Machine (SVM) model showed the best performance. In the training and validation cohorts, the SVM model had an area under the curve (AUC) of 0.993 (95% CI, 0.965–1); accuracy (ACC), 0.946 (95% CI, 0.877–1); sensitivity, 0.9 (95% CI, 0.696–1); and specificity, 0.964 (95% CI, 0.903–1). In the internal testing cohort, the SVM model had an AUC of 0.997 (95% CI, 0.992–1); ACC, 0.957 (95% CI, 0.945–0.988); sensitivity, 0.889 (95% CI, 0.888–0.889); and specificity, 0.973 (95% CI, 0.959–1). In the external testing cohort, the ACC was 0.991 (95% CI, 0.937–1). This model can detect AAS on NCCT, reducing misdiagnosis and improving examinations and prognosis.
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GER AKARSU, Fatma, Ezgi SEZER ERYILDIZ, Özlem AYKAÇ, Zehra UYSAL KOCABAŞ et Atilla Özcan Özdemir. « ASPECTS as a clinical outcome marker for MCA infarction treated with thrombolytic therapy : Non-contrast CT versus CTA source images ». Neurology Asia 27, no 2 (juin 2022) : 247–53. http://dx.doi.org/10.54029/2022kmj.
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Background & Objective: Computed tomography angiography (CTA) in acute stroke has been widely used to demonstrate arterial occlusion. Alberta Stroke Program Early CT Score (ASPECTS) is used to detect early ischemic signs in non-contrast computed tomography (NCCT) in the middle cerebral artery region. We hypothesized that computed tomography angiography source image (CTA-SI) is superior to NCCT in predicting final infarct volume, 24 hour National Institutes of Health Stroke Scale (NIHSS) score and 90-day clinical outcome. Methods: Patients who had an acute ischemic stroke due to middle cerebral artery (MCA) occlusion and treated with tissue plasminogen activator (tPA) were retrospectively evaluated. ASPECTS was evaluated by two experienced stroke neurologists in acute NCCT, CTA-SI, and follow up imaging. The final ASPECTS was compared with the mean baseline ASPECTS of NCCT and CTA-SI. The relation of both scores with 24-hour NIHSS and clinical outcome was compared. The Modified Rankin Scale (mRS) was utilized to evaluate the 90-day outcomes. mRS score of 0-2 was considered a “good outcome”. Results: Fifty-three patients were evaluated. We observed a significant relation among CTA-SI ASPECTS and after treatment 24hr ASPECTS (y= -3.9 + 1.4 x; 95% CI, -7.6 to -0.2) (y= -26.04 + 3.5 x; CI, -41 to -10). The median baseline 24-hr NHISS was 6 (0 - 22). We found a better correlation between CTA-SI ASPECTS and 24-hr NHISS (y= 363.06 + -37.03 x; CI, -148 to 864) than between NCCT ASPECTS and 24h NHISS (y=529.80 + -62.55 x; CI, 180 - 829). Median 90 days mRS score was 2 (0 - 6). According to Deming regression analysis, the CTA-SI ASPECTS (y= 76.10 + -7.69 x; 95% CI, -36 to 188) was more consistent with the 90 day mRS compared to NCCT ASPECTS (y=149.86 + -17.67 x; 95% CI, 23 - 267) CTA-SI was superior in predicting 24hr NIHSS and day 90 mRS compared to NCCT ASPECTS. Conclusion: Prediction of CTA-SI ASPECTs is better than NCCT ASPECTs at 24hr NIHSS, 3-month mRS and final infarct size in acute ischemic stroke patients treated with tPA.
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Schön, Felix, Hannes Wahl, Arne Grey, Pawel Krukowski, Angela Müller, Volker Puetz, Jennifer Linn et Daniel P. O. Kaiser. « Improved Visualization and Quantification of Net Water Uptake in Recent Small Subcortical Infarcts in the Thalamus Using Computed Tomography ». Diagnostics 13, no 22 (9 novembre 2023) : 3416. http://dx.doi.org/10.3390/diagnostics13223416.
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Diagnosing recent small subcortical infarcts (RSSIs) via early computed tomography (CT) remains challenging. This study aimed to assess CT attenuation values (Hounsfield Units (HU)) and net water uptake (NWU) in RSSI and explore a postprocessing algorithm’s potential to enhance thalamic RSSI detection. We examined non-contrast CT (NCCT) data from patients with confirmed thalamic RSSI on diffusion-weighted magnetic resonance imaging (DW-MRI) between January 2010 and October 2017. Co-registered DW-MRI and NCCT images enabled HU and NWU quantification in the infarct area compared to unaffected contralateral tissue. Results were categorized based on symptom onset to NCCT timing. Postprocessing using window optimization and frequency-selective non-linear blending (FSNLB) was applied, with interpretations by three blinded Neuroradiologists. The study included 34 patients (median age 70 years [IQR 63–76], 14 women). RSSI exhibited significantly reduced mean CT attenuation compared to unaffected thalamus (29.6 HU (±3.1) vs. 33.3 HU (±2.6); p < 0.01). Mean NWU in the infarct area increased from 6.4% (±7.2) at 0–6 h to 16.6% (±8.7) at 24–36 h post-symptom onset. Postprocessed NCCT using these HU values improved sensitivity for RSSI detection from 32% in unprocessed CT to 41% in FSNLB-optimized CT, with specificities ranging from 86% to 95%. In conclusion, CT attenuation values and NWU are discernible in thalamic RSSI up to 36 h post-symptom onset. Postprocessing techniques, particularly window optimization and FSNLB, moderately enhance RSSI detection.
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Toh, Tsun-Haw, Khairul Azmi Abdul Kadir, Mei-Ling Sharon Tai et Kay Sin Tan. « Acute Ischaemic Stroke Successfully Treated with Thrombolytic Therapy and Endovascular Thrombectomy with Non-Contrast Computed Tomography and Computed Tomography Angiogram Protocol ». Case Reports in Neurology 12, Suppl. 1 (14 décembre 2020) : 15–21. http://dx.doi.org/10.1159/000501820.
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Early endovascular thrombectomy leads to improved outcomes for patients with proximal occlusions when started within 6 h from onset of symptoms. We present a case illustrating the flow of events for a patient who underwent endovascular thrombectomy in our centre after conventional imaging – a brain non-contrast computed tomography (NCCT) and CT angiogram (CTA) – achieving a door-to-groin time of 195 min. The patient is a 65-year-old who presented with signs and symptoms of a left middle cerebral artery (MCA) territory infarct. His National Institute of Health Stroke Scale (NIHSS) score was 15 on presentation and his brain NCCT showed an Alberta Stroke Programme Early CT Score (ASPECTS) of 8. His CTA showed a left MCA distal M1 occlusion with focal calcification and stenosis of the proximal left internal carotid artery. He was subsequently thrombosed and underwent thrombectomy successfully, with a door-to-groin-puncture time of 195 min. A TICI 2b reperfusion was achieved. His NIHSS score improved to 9 over the next 2 days. For cases with straightforward NCCT and CTA with no contraindications, endovascular thrombectomy should be pursued without delay. A review of the current available literature for the usage of NCCT and CTA as well as the importance of ASPECTS scoring in patient selection for endovascular thrombectomy was included.
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Gariani, Joanna, Victor Cuvinciuc, Delphine Courvoisier, Bernhard Krauss, Vitor Mendes Pereira, Roman Sztajzel, Karl-Olof Lovblad et Maria Isabel Vargas. « Diagnosis of acute ischemia using dual energy CT after mechanical thrombectomy ». Journal of NeuroInterventional Surgery 8, no 10 (3 novembre 2015) : 996–1000. http://dx.doi.org/10.1136/neurintsurg-2015-011988.
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Background and purposeTo assess the performance of dual energy unenhanced CT in the detection of acute ischemia after mechanical thrombectomy.MethodsRetrospective study, approved by the local institutional review board, including all patients that underwent intra-arterial thrombectomy in our institution over a period of 2 years. The presence of acute ischemia and hemorrhage was evaluated by three readers. Sensitivity and specificity of the non-contrast CT weighted sum image (NCCT) and the virtual non-contrast reconstructed image (VNC) were estimated and compared using generalized estimating equations to account for the non-independence of regions in each patient.Results58 patients (27 women and 31 men; mean age 70.4 years) were included in the study, yielding 580 regions of interest. Sensitivity and specificity in detecting acute ischemia were higher for all readers when using VNC, with a significant increase in sensitivity for two readers (p<0.001 and 0.01) and a significant increase in specificity in one reader (p<0.001). Specificity in detecting hemorrhage was excellent for all readers.ConclusionsDual energy unenhanced CT VNC images were superior in the identification of acute ischemia in comparison with NCCT.
Thèses sur le sujet "Non-Contrast CT (NCCT)"
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Ma, Qixiang. « Deep learning based segmentation and detection of aorta structures in CT images involving fully and weakly supervised learning ». Electronic Thesis or Diss., Université de Rennes (2023-....), 2024. http://www.theses.fr/2024URENS029.
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La réparation endovasculaire des anévrismes aortiques abdominaux (EVAR) et l’implantation valvulaire aortique transcathéter (TAVI) sont des interventions endovasculaires pour lesquelles l’analyse des images CT préopératoires est une étape préalable au planning et au guidage de navigation. Dans le cas de la procédure EVAR, les travaux se concentrent spécifiquement sur la question difficile de la segmentation de l’aorte dans l’imagerie CT acquise sans produit de contraste (NCCT), non encore résolue. Dans le cas de la procédure TAVI, ils abordent la détection des repères anatomiques permettant de prédire le risque de complications et de choisir la bioprothèse. Pour relever ces défis, nous proposons des méthodes automatiques basées sur l’apprentissage profond (DL). Un modèle entièrement supervisé basé sur la fusion de caractéristiques 2D-3D est d’abord proposé pour la segmentation vasculaire dans les NCCT. Un cadre faiblement supervisé basé sur des pseudo-labels gaussiens est ensuite envisagé pour réduire et faciliter l’annotation manuelle dans la phase d’apprentissage. Des méthodes hybrides faiblement et entièrement supervisées sont finalement proposées pour étendre la segmentation à des structures vasculaires plus complexes, au-delà de l’aorte abdominale. Pour la valve aortique dans les CT cardiaques, une méthode DL de détection en deux étapes des points de repère d’intérêt et entièrement supervisée est proposée. Les résultats obtenus contribuent à l’augmentation de l’image préopératoire et du modèle numérique du patient pour les interventions endovasculaires assistées par ordinateurEndovascular aneurysm repair (EVAR) and transcatheter aortic valve implantation (TAVI) are endovascular interventions where preoperative CT image analysis is a prerequisite for planning and navigation guidance. In the case of EVAR procedures, the focus is specifically on the challenging issue of aortic segmentation in non-contrast-enhanced CT (NCCT) imaging, which remains unresolved. For TAVI procedures, attention is directed toward detecting anatomical landmarks to predict the risk of complications and select the bioprosthesis. To address these challenges, we propose automatic methods based on deep learning (DL). Firstly, a fully-supervised model based on 2D-3D features fusion is proposed for vascular segmentation in NCCTs. Subsequently, a weakly-supervised framework based on Gaussian pseudo labels is considered to reduce and facilitate manual annotation during the training phase. Finally, hybrid weakly- and fully-supervised methods are proposed to extend segmentation to more complex vascular structures beyond the abdominal aorta. When it comes to aortic valve in cardiac CT scans, a two-stage fully-supervised DL method is proposed for landmarks detection. The results contribute to enhancing preoperative imaging and the patient's digital model for computer-assisted endovascular interventions