正交偏振多光谱成像术应用于活体微循环观察研究

构建一种小型、简洁的活体微循环多光谱成像系统,将正交偏振光谱成像术OPS Imaging及液晶可调谐滤光片LCTF应用于活体微循环多光谱成像。LCTF具有较高的成像质量、较低的功耗、且没有移动部件和图像移动,能够连续、随机地在可见-近红外波段上快速实现波长的任意调谐。利用该系统,对活体裸鼠的耳廓采用检偏角为90°(正交偏振方式)与0°两种方式进行了试验,获取了裸鼠耳廓微血管的多光谱图,得出采用正交偏振成像方式的图像的对比度及图像细节均优于检偏角为0°时的图像。试验验证了正交偏振多光谱成像技术能增强活体微循环观察效果。     

Validation of optimal DCE-MRI perfusion threshold to classify at-risk tumor imaging voxels in heterogeneous cervical cancer for outcome prediction

Purpose

To classify tumor imaging voxels at-risk for treatment failure within the heterogeneous cervical cancer using DCE MRI and determine optimal voxel's DCE threshold values at different treatment time points for early prediction of treatment failure.

Material and Method

DCE-MRI from 102 patients with stage IB2–IVB cervical cancer was obtained at 3 different treatment time points: before (MRI 1) and during treatment (MRI 2 at 2–2.5 weeks and MRI 3 at 4–5 weeks). For each tumor voxel, the plateau signal intensity (SI) was derived from its time-SI curve from the DCE MRI. The optimal SI thresholds to classify the at-risk tumor voxels was determined by the maximal area under the curve using ROC analysis when varies SI value from 1.0 to 3.0 and correlates with treatment outcome.

Results

The optimal SI thresholds for MRI 1, 2 and 3 were 2.2, 2.2 and 2.1 for significant differentiation between local recurrence/control, respectively, and 1.8, 2.1 and 2.2 for death/survival, respectively.

Conclusion

Optimal SI thresholds are clinically validated to quantify at-risk tumor voxels which vary with time. A single universal threshold (SI = 1.9) was identified for all 3 treatment time points and remained significant for the early prediction of treatment failure.     

Blood viscosity in microvessels: Experiment and theory

The apparent viscosity of blood flowing through narrow glass tubes decreases strongly with decreasing tube diameter over the range from about 300 μm to about 10 μm. This phenomenon, known as the Fåhraeus–Lindqvist effect, occurs because blood is a concentrated suspension of deformable red blood cells with a typical dimension of about 8 μm. Most of the resistance to blood flow through the circulatory system resides in microvessels with diameters in this range. Apparent viscosity of blood in microvessels in vivo has been found to be significantly higher than in glass tubes with corresponding diameters. Here we review experimental observations of bloodʼs apparent viscosity in vitro and in vivo, and progress towards a quantitative theoretical understanding of the mechanisms involved.     

红花对兔肠缺血再灌注损伤后微循环改善作用的研究

目的探讨红花对兔肠缺血再灌注损伤(IRI)时微循环的改善作用.方法将30只日本大耳兔随机分为假手术组(S组)、缺血再灌注组(IR组)和缺血再灌注+红花注射液组(SI组).制作在体兔IRI模型.观察和记录各组动物肠系膜微循环变化,包括微动脉管径(AD)、微静脉管径(VD)、微动脉流速(AFV)、微静脉流速(VFV)和白细胞黏附数,电镜下观察肠黏膜超微结构改变.结果 IR组肠系膜微动、静脉管径缩小,血流速度减慢,多数肠黏膜微结构破坏严重.SI组微动、静脉管径及血流速度明显改善,肠黏膜超微结构异常改变不同程度减轻.结论在兔肠IRI发生后使用红花注射液能有效改善肠系膜的微循环,从而对肠黏膜起到良好的保护作用.     

利用变偏振光谱技术实现显微成像深度选择

在正交偏振光谱(OPS)微循环成像系统的基础上,提出了通过改变信号光的偏振态来实现成像深度的选择。传统的OPS系统利用的是正交线偏振光,只能获得图像在某一断层的二维信息,但作者通过控制系统起、检偏单元椭圆偏振光的椭圆度,可以在不进行机械扫描的情况下将成像光束聚焦在不同的断层,从而获得不同深度处的组织信息。构建的变偏振光谱成像系统将光源发射光谱与红血球吸收光谱相匹配,可以实现微血管的探测,且具有较高的信噪比。对一块含标记物的猪肉脂肪进行实验,并通过图像处理得到了对比度与信号光偏振态间的定量关系。实验结果表明：椭圆度由0°～45°增大,即从线偏振光向圆偏振光转变的过程中,对比度逐渐增大,可探测到的最大深度增大。最后利用该系统,对裸鼠耳廓微血管进行了变偏振光谱测量实验,实验证明了控制偏振态可以实现对血管不同深度的探测,为微血管断层光谱成像提供了一种新的研究手段。     

A continuum model of the blood flow in the lung microcirculation

An one-dimensional continuum model and the corresponding governing equations are proposed for the blood flow in lung microcirculation, the analytical solutions in closed form are presented. It is shown that the obtained results coincide with Fung's in sheet flow. Project is supported by the National Natural, Science Fundation of China.