Comparison of 2 shear wave elastography systems in reproducibility and accuracy using an elasticity phantom

This study aimed to compare the accuracy and inter- and intra-observer reproducibility of the measured elasticity between 2 shear wave elastography systems. Three breast radiologists examined 8 targets of 4 different levels of stiffness (size: 11 mm, 4 mm) in an elasticity phantom (Customized 049A Elasticity QA Phantom, CIRS, Norfolk, VA, USA) using 2 different shear wave ultrasound elastography systems: SuperSonic Imagine (SSI) (SSI, Aix en Provence, France) and ShearScan (RS-80A, Samsung Medison, Seoul, Korea). Three radiologists performed ultrasound (US) elastography examinations for the phantom lesions using 2 equipment over a 1-week interval. Intra- and inter-observer reproducibility and the accuracy of the measured elasticity were analyzed and compared between the 2 systems. The accuracy of shape was also analyzed by shape-matching between B-mode and elastography color image. Intra-class correlation coefficients (ICC) were used in statistical analysis. For measured elasticity, the intra-observer and inter-observer reproducibility were excellent in both SSI and ShearScan (0.994 and 0.998). The overall accuracy was excellent in both systems, but the accuracy in small lesions (4 mm target) was lower in SSI than ShearScan (0.780 vs 0.967). The accuracy of shape-matching on the elastography image was 59.0% and 81.4% in the SSI and ShearScan, respectively. In conclusion, the SSI and ShearScan showed excellent intra- and inter-observer reproducibility. The accuracy of the Young''s modulus was high in both the SSI and ShearScan, but the SSI showed decreased accuracy in measurement of elasticity in small targets and poor shape-matching between the B-mode image and color-coded elastography image.     

Shear wave elastography of the tibial nerve in healthy subjects

The purpose of this study is to investigate sonoelastographic features of the tibial nerve.The study included 72 tibial nerves in 36 healthy subjects. High resolution ultrasound and Shear wave elastography were used to evaluate the tibial nerve. Cross sectional area and stiffness were measured.The mean cross sectional area of the tibial nerve was 13.4 mm². The mean shear elastic modulus of the tibial nerve in the short axis was 23.3 kPa. The mean shear elastic modulus of the tibial nerve in long axis was 26.1 kPa. The tibial nerve elastic modulus also showed no correlation with cross sectional area neither in the long axis nor short axis. Age, height, weight, and body mass index showed no correlation with tibial nerve elastic modulus in short or long axes.The elastic modulus of the tibial nerve has been determined in healthy subjects and can serve as a reference for future assessment of polyneuropathy.     

Role of hemodynamics in initiation/growth of intracranial aneurysms

Background

Intracranial aneurysm (IA) is a disease of the vascular wall resulting in abnormal enlargement of the vessel lumen. It is a common pathology with a prevalence of 2%‐3% in the adult population. IAs are mostly small, quiescent and asymptomatic; yet, upon rupture, severe brain damage or even death is frequently encountered. In addition to clinical factors, hemodynamic forces, mainly wall shear stress (WSS), have been associated with the initiation of IAs and possibly with their risk of rupture. However, the mechanism by which WSS contributes to aneurysm growth and rupture is not completely understood.

Design

PubMed and Ovid MEDLINE databases were searched. In addition, key review articles were screened for relevant original publications.

Results

Current knowledge about the relation between WSS and IA has been obtained from both computational fluid dynamic studies in patients and experimental models of IA formation and growth. It is increasingly recognized that a high wall shear stress (gradient) participates to IA formation and that both low and high WSS can drive IA growth. Primary cilia (PC) play an important role as mechanosensors as patients with polycystic kidney disease, which is characterized by the absence or dysfunction of PC, have increased risk to develop IAs as well as increased risk of rupture.

Conclusion

Wall shear stress is a key player in IA initiation and progression. It is involved in vascular wall remodelling and inflammation, processes underlying aneurysm pathophysiology.     

Effect of fluid shear stress on the internalization of kidney-targeted delivery systems in renal tubular epithelial cells

Renal tubular epithelial cells (RTECs) are important target cells for the development of kidney-targeted drug delivery systems. Under physiological conditions, RTECs are under constant fluid shear stress (FSS) from original urine in the renal tubule and respond to changes of FSS by altering their morphology and receptor expression patterns, which may affect reabsorption and cellular uptake. Using a microfluidic system, controlled shear stress was applied to proximal tubule epithelial cell line HK-2. Next, 2-glucosamine, bovine serum albumin, and albumin nanoparticles were selected as representative carriers to perform cell uptake studies in HK-2 cells using the microfluidic platform system with controlled FSS. FSS is proven to impact the morphology of HK-2 cells and upregulate the levels of megalin and clathrin, which then led to enhanced cellular uptake efficiencies of energy-driven carrier systems such as macromolecular and albumin nanoparticles in HK-2 cells. To further investigate the effects of FSS on endocytic behavior mediated by related receptors, a mice model of acute kidney injury with reduced fluid shear stress was established. Consistent with in vitro findings, in vivo studies have also shown reduced fluid shear stress down-regulated the levels of megalin receptors, thereby reducing the renal distribution of albumin nanoparticles.     

SWE联合灰阶超声评估不同分度子宫脱垂初产妇会阴体变化

目的利用实时剪切波弹性成像技术(SWE)联合灰阶超声探讨产后不同分度子宫脱垂初产妇会阴体弹性和形态的变化。方法选取2019年1月~2019年12月200例产后6~8周,患有子宫脱垂且经阴道单胎足月顺产的初产妇为观察对象。通过经阴道超声检查,结合POP分度标准,将患有Ⅰ度子宫脱垂的65例初产妇纳入B组,Ⅳ度子宫脱垂的46例初产妇纳入C组。收集同期健康已婚未育女性50例作为对照,纳入A组。分别在静息及缩肛状态下,测量三组观察对象会阴体的高度及深度,采集各组会阴体的杨氏模量值。结果三组观察对象的会阴体收缩幅度差值(高度、深度)在缩肛、静息两种状态下,差异有统计学意义(P均<0.05);静息及缩肛两种状态下健康对照组会阴体的平均杨氏模量值较Ⅰ度子宫脱垂组、Ⅳ度子宫脱垂组高,且Ⅰ度子宫脱垂组高于Ⅳ度子宫脱垂组,各组间差异均有统计学意义(P<0.05)。结论产后子宫脱垂初产妇会阴体弹性明显降低,收缩功能减弱,且会阴体收缩功能减低程度与子宫脱垂程度有关。     

Rheological studies on the solubilization by the surfactant SDS of complexes between three acidic polysaccharides and an organic base chloride

Developments in the solubilization of complexes between the cationic polymer, poly(hexamethylenebiguanidinium chloride) (PHMBH⁺Cl^-) and acidic polysaccharides are reported. It was discovered that the anionic detergent sodium dodecyl sulphate (SDS) is an excellent solubilizer for these complexes, enabling several multi-component systems to be studied. SDS itself was shown to interact with PHMBH⁺CL^- to form a highly viscous solution. Maximum viscosity was obtained with a SDS : PHMBH⁺CL^- molar ratio of 15.6. SDS : PHMBH⁺Cl^- at this ratio served as a good solubilizer for the acidic polysaccharides (sodium alginate, sodium carboxymethyl cellulose, and xanthan), forming highly viscous fluids. The effect of temperature on the viscosity of these solutions was also examined.