Noninvasive model for predicting future ischemic strokes in patients with silent lacunar infarction using radiomics.

BACKGROUND: This study aimed to investigate integrating radiomics with clinical factors in cranial computed tomography (CT) to predict ischemic strokes in patients with silent lacunar infarction (SLI). METHODS: Radiomic features were extracted from baseline cranial CT images of patients with SLI. A least absolute shrinkage and selection operator (LASSO)-Cox regression analysis was used to select significant prognostic factors based on ModelC with clinical factors, ModelR with radiomic features, and ModelCR with both factors. The Kaplan-Meier method was used to compare stroke-free survival probabilities. A nomogram and a calibration curve were used for further evaluation. RESULTS: Radiomic signature (p < 0.01), age (p = 0.09), dyslipidemia (p = 0.03), and multiple infarctions (p = 0.02) were independently associated with future ischemic strokes. ModelCR had the best accuracy with 6-, 12-, and 18-month areas under the curve of 0.84, 0.81, and 0.79 for the training cohort and 0.79, 0.88, and 0.75 for the validation cohort, respectively. Patients with a ModelCR score < 0.17 had higher probabilities of stroke-free survival. The prognostic nomogram and calibration curves of the training and validation cohorts showed acceptable discrimination and calibration capabilities (concordance index [95% confidence interval]: 0.7864 [0.70-0.86]; 0.7140 [0.59-0.83], respectively). CONCLUSIONS: Radiomic analysis based on baseline CT images may provide a novel approach for predicting future ischemic strokes in patients with SLI. Older patients and those with dyslipidemia or multiple infarctions are at higher risk for ischemic stroke and require close monitoring and intensive intervention.

[3-D finite element analysis on center of resistance of upper anterior teeth].

PURPOSE: To investigate the location of center of resistance(CRe) of six upper anterior teeth. METHODS: A three-dimensional finite element model of premaxillary bone and anterior teeth was established in ANSYS 8.1 software. Anterior teeth were fixed with stainless archwire of 2 mm × 2 mm. A horizontal retraction force of 150 g was applied bilaterally to the segment through hooks of 2 to 14 mm. After loading, solution was done and displacement and maximum principle stress were calculated. RESULTS: Displacement and stress distribution of anterior teeth varied according to the increase of height of horizontal retraction force. Labiolingual displacement of incisors varied from crown lingual tipping to lingual translation and lingual controlling root movement, while canine mainly showed lingual crown tipping. The displacements of teeth increased with the length of hook but their moving tendency remained unchanged. Stress distribution in PDL was in accordance with direction and magnitude of teeth displacement. In all cases, lingual displacement and stress in PDL were most homogeneous when hook was 10 mm long. CONCLUSION: The results of this study suggest that perpendicular location of center of resistance of six upper anterior teeth is about 14 mm gingivally to incisal edge of central incisor.