分频辐去相干影像OCT技术对脉络膜新生血管的定量分析

背景脉络膜新生血管（CNV）是多种眼底病变视力损害的主要原因，传统的CNV检测和评价方法主要依靠眼底血管造影术，但为有创检查方法。分频辐去相干影像（SSADA）OCT可快速获得清晰的血管信号，但SSADA—OCT对CNV的检测价值尚不清楚。目的利用SSADA—OCT检测并定量分析CNV的血流信息，评价其在眼科临床的应用价值。方法纳入2014年6—8月于首都医科大学附属同仁医院眼科中心确诊的单眼CNV患者13例，应用高速频域OCT系统扫描黄斑中心6mm×6mm区域，最终得到SSADA—OCT血流图像。应用Photoshop软件分别在视网膜和脉络膜层面上测量CNV面积并计算平均灰度值。结果SSADA—OCT可显示视网膜内界膜层、内丛状层、视网膜色素上皮（RPE）层及脉络膜层面血流情况。不同病因CNV患者的SSADA—OCT表现均呈黄斑区边界清楚的团状高反射信号。13例CNV患者患眼平均CNV面积为（0．15±0．09）mm^2，平均灰度值为75．40±32．35，对侧眼选择黄斑中心300μm的区域进行测量，平均灰度值为26．99±22．87，患眼CNV平均灰度值明显高于对侧眼，差异有统计学意义（t=6．946，P〈0．001）。结论OCT血管影像技术是一种快速、非侵人的视网膜及脉络膜血流观察技术，可对CNV的面积和活动性进行定量分析。

Vessel density and En-face segmentation of optical coherence tomography angiography to analyse corneal vascularisation in an animal model

Background:Optical coherence tomography angiography(OCTA)is a novel non-invasive angiography technology that has recently been extensively studied for its utility in anterior segment imaging.In this study,we compared a split-spectrum amplitude decorrelation angiography(SSADA)OCTA and an optical micro-angiography(OMAG SD)OCTA system to current angiographic technique,indocyanine green angiography(ICGA),to assess corneal vascularisation in an animal model.Methods:We imaged 16 rabbits,(one eye per animal)with corneal vascularisation using SSADA OCTA(AngioVue;Optovue Inc.,USA),OMAG OCTA(Angioscan;RS-3000 Nidek Co.Ltd.,Japan)and ICGA in the same region of interest of the cornea at successive time-points.We then analysed all scanned images for vessel density measurements and used paired t-tests and Bland-Altman plots to examine for significant differences.The en-face segmentation images from each of the OCTA scans were also extracted and were matched at every 50μm segmentation to be compared for vessel density at the respective depths.Results:Bland-Altman plots revealed a good agreement between all three imaging techniques(P>0.05)for all vessel density measurements computed,and the ranges of 95%limit of agreement were acceptable from a clinical perspective.No significant difference was reported,with ICGA(μ=16.52±8.94%)being more comparable to the OMAG OCTA(μ=16.23±9.51%;p=0.50)than the SSADA OCTA(μ=17.09±7.34%;p=0.33)system.Also,a good correlation value(r>0.9)was obtained when comparing the vessel density measurements of the en-face segmentations between the OCTA systems.Conclusions:Comparable vessel density quantification between the two OCTA systems,and with ICGA was obtained.Segmentation analysis of the vasculature at different depths showed varied performance in the two OCTA systems relative to each other.The implications of the study may help to aid in the development of better OCTA algorithms for the anterior segment and its use in clinical translational research.

相干光断层扫描血管成像技术临床应用前景

相干光断层扫描(OCT)是眼科发展最迅速的检查之一,而OCT血管成像是近年来OCT发展的新兴领域,是目前唯一无创、无需造影剂的眼底血管成像技术,逐渐被应用于眼底病的临床诊断与鉴别诊断及随诊等方面,在眼科疾病的诊治中有着广阔的应用前景。

分频幅去相干血管成像

相干光断层扫描血管成像（optical coherence tomography angiography，OCTA）通过比较同一位置的不同扫描，去除不变的结构，即可在不使用造影剂的情况下观察到有红细胞流动的视网膜和脉络膜血管结构。目前，一种新的运算方法——分频幅去相干血管成像（split—spectrum amplitude decorrelation angiography，SSADA）的应用，大大改善了OCTA的信噪比。与其他OCTA不同的是，SSA—DAOCT可获取与OCT光波平行或垂直的血流信号，不依赖多普勒角，并且图像噪音、组织运动等噪音较小。目前SSADAOCT已越来越多地应用于多种眼部疾病中，如脉络膜新生血管性疾病、糖尿病视网膜病变，视网膜血管阻塞等，在这些疾病的诊断、随访中均有重要意义。