Hemodynamics in nutcracker syndrome: implications for diagnosis.

BACKGROUND: Nutcracker syndrome is a disease characterized by complex symptoms, making its diagnosis challenging and often delayed, often resulting in a painful experience for the patients. OBJECTIVE: This study aimed to investigate the pathogenesis of nutcracker syndrome through the perspective of hemodynamics by simulating blood flow with varying compression degrees of the left renal vein. METHODS: 3D patient-specific vascular models of the abdominal aorta, superior mesenteric artery and left renal vein were constructed based on CT images of patients suspected of having nutcracker syndrome. A hemodynamic simulation was then conducted using computational fluid dynamics to identify the correlation between alterations in hemodynamic parameters and varying degrees of compression. RESULTS: The study indicated the presence of an evident gradient in velocity distribution over the left renal vein with relatively high degrees of stenosis (α ≤ 50°), with maximum velocity in the central region of the stenosis. Additionally, when the compression degree of the left renal vein increases, the pressure distribution of the left renal vein presents an increasing number of gradient layers. Furthermore, the wall shear stress shows a correlation with the variation of blood flow velocity, i.e., the increase of wall shear stress correlates with the acceleration of the blood flow velocity. CONCLUSIONS: Using computational fluid dynamics as a non-invasive instrument to obtain the hemodynamic characteristics of nutcracker syndrome is feasible and could provide insights into the pathological mechanisms of the nutcracker syndrome supporting clinicians in diagnosis.

A novel immune-related prognostic model with surgical status to predict tumor immune cell infiltration and drug sensitivity in head and neck squamous cell carcinoma.

Tumor-infiltrating immune cells (TICs) affect tumorigenesis and tumor development in head and neck squamous cell carcinoma (HNSCC). We constructed a novel predictive model for HNSCC based on immune-related genes (IRGs) from The Cancer Genome Atlas and the Immunology Database and Analysis Portal. After identifying the IRGs, a predictive model involving 13 IRGs with high stratification value of overall survival (OS) was constructed by multiple support vector machine recursive feature elimination and least absolute shrinkage and selection operator regression. We explored the relationship between the risk score (RS) and clinical characteristics. The nomogram showed high concordance and good agreement in OS. Four TICs affected the OS and were in agreement with the abundance analysis of the RS levels. Furthermore, the low-risk HNSCC group showed higher expression of PD-1, CTLA4, and TIGIT, while the high-risk group showed higher expression of EGFR. The high-risk HNSCC showed high sensitivity to eight drugs.

Time-resolved simulation of blood flow through left anterior descending coronary artery: effect of varying extent of stenosis on hemodynamics.

BACKGROUND AND OBJECTIVES: Real-time blood flow variation is crucial for understanding the dynamic development of coronary atherosclerosis. The main objective of this study is to investigate the effect of varying extent of stenosis on the hemodynamic features in left anterior descending coronary artery. METHODS: Various Computational fluid dynamics (CFD) models were constructed with patient-specific CT image data, using actual fractional flow reserve (FFR) as boundary conditions to provide a real-time quantitative description of hemodynamic properties. The hemodynamic parameters, such as the local and instantaneous wall shear stress (WSS), oscillating shear index (OSI) and relative residence time (RRT), blood flow velocity and pressure drop during various phases of cardiac cycle were provided in detail. RESULTS: There was no evident variation in hemodynamic parameters in the cases of less than 50% stenosis while there were abrupt and dramatic changes in hemodynamics when the stenosis aggravated from 60 to 70%. Furthermore, when the stenosis was beyond 70%, there existed substantial pressure difference, WSS, and blood flow velocity in the center of the stenosis. Although OSI and RRT increased along with the aggravation of stenosis, they appeared with obvious abnormalities across all cases, even in mild stenosis. CONCLUSION: The simulation could present a dynamic and comprehensive profile of how hemodynamic parameters vary in accordance with divergent severities of stenosis, which could serve as an effective reference for the clinicians to have a deeper insight into the pathological mechanism of coronary atherosclerosis and stenosis.

General Adsorption Model to Describe Sigmoidal Surface Tension Isotherms of Binary Liquid Mixtures.

Surface tension (σ) isotherms of liquid mixtures can be divided into Langmuir-type (L-type, including LI- and LII-type) and sigmoid-type (S-type, including SI- and SII-type). Many models have been developed to describe the σ-isotherms. However, the existing models can well describe the L-type isotherms, but not the S-type ones. In the current work, a thermodynamic model, called the general adsorption model, was developed based on the assumption of surface aggregation occurring in the surface layers, to relate the surface composition with the bulk one. By coupling the general adsorption model with the modified Eberhart model, a two-parameter equation was developed to relate the σ with the bulk composition. Its rationality was examined using the σ data of 10 binary mixtures. The results indicate that the new model can accurately describe the S- and L-type isotherms of binary liquid mixtures, showing a good universality. One advantage of the model is that its two parameters, i.e., the adsorption equilibrium constant (K) and the average aggregation number (n), can be estimated by linear fitting experimental σ data, thereby obtaining unique values. This model suggests that the S- and LII-type isotherms arise from the surface aggregation (n ≠ 1). In addition, the standard molar Gibbs free energy of surface adsorption (ΔG̃ad0) and the apparent surface layer thickness (τ) were analyzed for 10 binary mixtures. The ΔG̃ad0 data suggest that the order of adsorption tendency is LI-type ≫ SI-type ≈ SII-type > LII-type, and the strong adsorption usually corresponds to large τ. This work provides a feasible model for describing the S-type isotherms and a better understanding of the surface properties of liquid mixtures.

Comparison of Silicosis and Tuberculosis Involving Mediastinal Lymph Nodes Based on Contrast-Enhanced Multidetector-Row Computed Tomography.

PURPOSE: To investigate the different imaging features of contrast-enhanced multidetector-row-computed tomography (MDCT) for distinguishing between silicosis and tuberculosis involving the mediastinal lymph nodes. METHODS: 86 silicosis patients and 61 tuberculosis patients with mediastinal lymphadenopathy based on contrast-enhanced MDCT were included. The enhanced patterns, anatomical distribution and calcification features of the enlarged lymph nodes were retrospectively compared between the groups using the Pearson chi-square test or Fisher's exact test. RESULTS: Homogeneous enhancement of the mediastinal lymph nodes was more commonly observed in silicosis (94.2%, 81/86) than in tuberculosis (19.7%, 12/61). Peripheral enhancement was more frequent in tuberculosis (n = 44, 72.1%) than in silicosis involving the mediastinal lymph nodes (n = 1, 1.2%), and multilocular appearance was more frequent in TB than in silicosis. Tuberculosis was more likely to affect regions 1R, 2R, 2L, 3A, 5 and 6 than silicosis (all p < 0.05), especially region 2R. Calcification of the lymph nodes was more common in the silicosis group than in tuberculosis group. The sensitivity, specificity, and accuracy of silicosis with lymphadenopathy with homogeneous enhanced pattern were 94.2%, 80.3% and 88.4%, respectively. The sensitivity, specificity, and accuracy of tuberculosis lymphadenopathy with peripheral enhanced pattern were 72.1%, 98.8%, and 87.7%, respectively. CONCLUSION: The predominant enhanced patterns, anatomical distribution, and calcification features of mediastinal lymph nodes were different between tuberculosis and silicosis. These radiographic features might help differentiate tuberculosis from silicosis, which provides imaging information for the differential diagnosis of the two diseases in a clinical setting.

Computational fluid dynamics simulation of time-resolved blood flow in Budd-Chiari syndrome with inferior vena cava stenosis and its implication for postoperative efficacy assessment.

BACKGROUND: This study aimed to adopt computational fluid dynamics to simulate the blood flow dynamics in inferior vena cava stenosis based on time-dependent patient-specific models of Budd-Chiari syndrome as well as a normal model. It could offer valuable references for a retrospective insight into the underlying mechanisms of Budd-Chiari syndrome pathogenesis as well as more accurate evaluation of postoperative efficacy. METHODS: Three-dimensional inferior vena cava models of Budd-Chiari syndrome patient-specific (preoperative and postoperative) and normal morphology model were reconstructed as per magnetic resonance images using Simpleware. Moreover, computational fluid dynamics of time-resolved inferior vena cava blood flow were simulated using actual patient-specific measurements to reflect time-dependent flow rates. FINDINGS: The assessment of the preoperative model revealed the dramatic variations of hemodynamic parameters of the stenotic inferior vena cava. Moreover, the comparison of the preoperative and postoperative models with the normal model as benchmark showed that postoperative hemodynamic parameters were markedly ameliorated via stenting, with the attenuation of overall velocity and wall shear stress, and the increase of pressure. However, the comparative analysis of the patient-specific simulations revealed that some postoperative hemodynamic profiles still bore some resemblance to the preoperative ones, indicating potential risks of restenosis. INTERPRETATION: Computational fluid dynamics simulation of time-resolved blood flow could reveal the tight correlation between the hemodynamic characteristics and the pathological mechanisms of inferior vena cava stenosis. Furthermore, such time-resolved hemodynamic profiles could provide a quantitative approach to diagnosis, operative regimen and postoperative evaluation of Budd-Chiari syndrome with inferior vena cava stenosis.

Fractional flow reserve-based 4D hemodynamic simulation of time-resolved blood flow in left anterior descending coronary artery.

BACKGROUND: The purpose of this study was to investigate the feasibility of the non-invasive assessment of hemodynamic parameters with computational fluid dynamics in left anterior descending coronary artery based on invasive fractional flow reserve. METHODS: A left coronary artery model based on computed tomography angiography was reconstructed using MIMICS 18.0 for computational fluid dynamics analysis. With actual fractional flow reserve measured from the patient, 4D hemodynamic profiles of time-resolved blood flow were simulated. FINDINGS: The 4D blood flow simulation could provide extensive information of blood flow status. Hemodynamic parameters, such as velocity, wall shear stress and pressure were simulated throughout the cardiac cycle. There might be high flow velocities and high wall shear stress in the stenotic region throughout the whole cycle, both of which peaked in the case of the maximum inlet differential pressure. The reverse flow and vortex were detectable at the downstream areas beneath the stenotic site. The pressure remarkably increased near the proximal stenotic end and declined in the mid-stenosis. Moreover, the simulation results provided detailed and accurate mass flow measurements of hemodynamic parameters as well. INTERPRETATION: The computational fluid dynamics analysis of 4D blood flow based on fractional flow reserve is feasible in left anterior descending coronary artery. It presents the merits of providing both qualitative and quantitative information for further investigation of the links between hemodynamic parameters and left anterior descending artery stenosis.