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Ma Chao,Zhu Haoyu,Liang Shikai,Chang Yuzhou,Mo Dapeng,Jiang Chuhan,Zhang Yupeng 대한영상의학회 2024 Korean Journal of Radiology Vol.25 No.1
Objective: Idiopathic intracranial hypertension (IIH) is a condition of unknown etiology associated with venous sinus stenosis. This study aimed to develop a magnetic resonance venography (MRV)-based radiomics model for predicting a high trans-stenotic pressure gradient (TPG) in IIH patients diagnosed with venous sinus stenosis. Materials and Methods: This retrospective study included 105 IIH patients (median age [interquartile range], 35 years [27– 42 years]; female:male, 82:23) who underwent MRV and catheter venography complemented by venous manometry. Contrast enhanced-MRV was conducted under 1.5 Tesla system, and the images were reconstructed using a standard algorithm. Shape features were derived from MRV images via the PyRadiomics package and selected by utilizing the least absolute shrinkage and selection operator (LASSO) method. A radiomics score for predicting high TPG (≥ 8 mmHg) in IIH patients was formulated using multivariable logistic regression; its discrimination performance was assessed using the area under the receiver operating characteristic curve (AUROC). A nomogram was constructed by incorporating the radiomics scores and clinical features. Results: Data from 105 patients were randomly divided into two distinct datasets for model training (n = 73; 50 and 23 with and without high TPG, respectively) and testing (n = 32; 22 and 10 with and without high TPG, respectively). Three informative shape features were identified in the training datasets: least axis length, sphericity, and maximum three-dimensional diameter. The radiomics score for predicting high TPG in IIH patients demonstrated an AUROC of 0.906 (95% confidence interval, 0.836– 0.976) in the training dataset and 0.877 (95% confidence interval, 0.755–0.999) in the test dataset. The nomogram showed good calibration. Conclusion: Our study presents the feasibility of a novel model for predicting high TPG in IIH patients using radiomics analysis of noninvasive MRV-based shape features. This information may aid clinicians in identifying patients who may benefit from stenting.
Fuwei Li,Jie He,Peng Luo,Haoyu Jiang,Mingxin Liu 전력전자학회 2023 JOURNAL OF POWER ELECTRONICS Vol.23 No.4
This paper presents a quadratic-type high step-up DC–DC converter for renewable energy applications with a continuousinput current. To reduce the number of components while increasing the gain, a quadratic boost converter and two multiplier cells are applied as the primary and secondary circuit with one coupled inductor connected. In addition, the clamp circuit shares its components with both the second boost stage and the voltage multiplier, which increases the power density. As a result, the leakage energy is recycled and the voltage stress can be suppressed. The operation principles and steady-state analyses including loss analysis of the proposed converter are addressed in detail. Compared with relevant existing topologies of quadratic converter, the proposed converter performs a higher voltage gain and a lower power switch stress. To validate the performance, a 200 W experimental prototype is constructed and tested with 20 V of input voltage and 400 V of output voltage, where the highest efficiency is 95.2% and the full-load efficiency is 93.7%. The performance under dynamic conditions is also verified. In the end, an improved topology based on the proposed converter is supplemented.