A newly formed and ruptured atheromatous plaque within neointima after drug-eluting stent implantation: 2-year follow-up intravascular ultrasound and optical coherence tomography studies

Late stent thrombosis (LST) which is a life threatening complication has emerged as a serious problem of drug-eluting stents (DES). Several studies have suggested that incomplete neointimal coverage of stent struts contributes to LST. Progressive atherosclerosis within the neointima is an another possible cause of LST, but this phenomenon has seldom been reported in DES. We present a case of LST following DES implantation after a period of 28 months due to ruptured atheromatous plaque, despite complete neointimal coverage of stent struts proven by optical coherence tomography.     

光相干层析成像中的散斑

由于光相干层析成像中测量的干涉信号空间频带有限 ,因此会产生散斑。在高散射的生物组织图像中 ,散斑具有双重身份 ,即作为噪声源和作为组织微结构的信号载体。本文的前半部分对于光相干层析成像中散斑的产生原因、统计特性以及分类作了综述。通过采样束的相位和振幅扰动可以定义信号载体散斑和信号降低散斑。本文的后半部分讨论了减少散斑的 4种方法 :偏振合成法、空间合成法、频率合成法和数字信号处理方法 ,并且通过举例对每一种方法的有效性作了简单的分析。最后 ,文章提出了需进一步研究的问题     

定量血管内光学相干层析成像的研究进展

血管内光学相干层析成像(IVOCT)是目前分辨率最高的血管内成像技术,可对冠状动脉血管腔及管壁内膜下病变进行快速、清晰的成像。仅根据组织结构的层析图像无法精确识别粥样硬化斑块成分(如钙化、纤维化、脂质和混合斑块),需要形态结构之外的生理信息的对比机制,获得具有临床诊断价值的组织参数,即定量IVOCT(qIVOCT)。本文针对根据IVOCT原始背向散射信号和灰阶图像定量测量血管壁组织的光学特性参数、弹性参数和血流动力学参数的研究现状进行归纳和总结,分析目前存在的问题,展望可能的发展方向。     

早期糖尿病患者黄斑区光学相干断层扫描的分析

目的 利用光学相干断层扫描(OCT)测量并分析早期糖尿病(DM)患者的黄斑区视网膜厚度.方法 正常对照组30例60只眼,其中男性15例,女性15例;年龄38～71岁,平均年龄51岁.DM组60例120只眼,其中男性30例,女性30例;年龄32～73岁,平均年龄54.5岁.患有DM但不伴或伴有轻微视网膜病变的患者被纳入研...     

基于形态学去噪的兔眼相干光断层成像中角膜形态自动识别

目的对兔眼相干光断层成像(optical coherence tornography,OCT)中的角膜边缘识别进行研究,以期从不具有较高清晰度的图像中自动获得角膜边缘以及相关形态学参数。方法首先利用Otsu算法对兔眼OCT图像进行二值化,并以半径为5像素的圆盘形结构元素进行形态学去噪运算消除内部伪边缘,通过Canny算子获得角膜边缘图像;然后使用筛选过错误边缘点后的其余边缘点进行边缘的二次曲线一般方程的曲线拟合,求出各点曲率半径;最后用克朗巴哈系数法与人工描绘的边缘获得的相应点的曲率半径进行一致性检验。结果基于形态学去噪的Canny算法获得了较为连续平滑的角膜内外边缘曲线,与手工标点拟合曲线求出的曲率半径值具有较高的一致性(Cronbach’sα=0.953,P0.05)。结论基于形态学去噪的Canny算法可以较为准确地对OCT图像中的兔眼角膜的形态进行识别。     

High-resolution in vivo imaging of the cross-sectional deformations of contracting embryonic heart loops using optical coherence tomography.

The embryonic heart tube consists of an outer myocardial tube, a middle layer of cardiac jelly, and an inner endocardial tube. It is said that tubular hearts pump the blood by peristaltoid contractions. The traditional concept of cardiac peristalsis sees the cyclic deformations of pulsating heart tubes as concentric narrowing and widening of tubes of circular cross-section. We have visualized the cross-sectional deformations of contracting embryonic hearts in chick embryos (HH-stages 9-17) using real-time high-resolution optical coherence tomography. Cardiac contractions are detected from HH-stage 10 onward. During the cardiac cycle, the myocardial tube undergoes concentric narrowing and widening while the endocardial tube undergoes eccentric narrowing and widening, having an elliptic cross-section at end-diastole and a slit-shaped cross-section at end-systole. The eccentric deformation of the endocardial tube is the consequence of an uneven distribution of the cardiac jelly. Our data show that the cyclic deformations of pulsating embryonic heart tubes run other than originally thought. There is evidence that heart tubes of elliptic cross-section might pump blood with a higher mechanical efficiency than those of circular-cross section. The uneven distribution of cardiac jelly seems to prefigure the future AV and cono-truncal endocardial cushions.     

频域光学相干断层扫描增强技术观察糖尿病视网膜病变激光光凝术前后黄斑区脉络膜体积的变化

目的：应用频域光学相干断层扫描增强技术(enhanced-depth imaging optical coherence tomography, OCT)观察糖尿病视网膜病变(diabetic retinopathy,DR)在视网膜激光光凝术前后黄斑区脉络膜体积(macular choroidal volume,MCV)的变化情况。方法：经眼底血管造影(fundus fluorescein angiography,FFA)和光学相干断层扫描(optical coherence tomography,OCT)确诊重度非增殖期糖尿病视网膜病变(non-proliferative diabetic retinopathy,NPDR)和早期增殖期糖尿病视网膜病变(proliferative diabetic retinopathy,PDR)伴黄斑水肿(diabetic macular edema,DME)的患者30例(51只眼)纳入研究。所有患眼均先行黄斑区格栅样激光光凝治疗,然后1周后行全视网膜激光光凝术(panretinal photocoagulation,PRP)。治疗前、黄斑区格栅样激光光凝完成后1周及PRP全部治疗完成后1个月和三个月,分别采用频域OCT增强深部成像技术(enhanced-depth imaging,EDI)技术对所有患眼黄斑区脉络膜进行水平扫描,测量计算出MCV值。结果：治疗前MCV值为(6.38±0.69) mm3,黄斑区格栅样激光光凝术后1周MCV值为(7.79±0.70) mm3,较治疗前增大(1.56±0.32) mm3,差异有统计学意义(t=3.265,P<0.05),PRP术后一个月MCV值为(7.01±0.71) mm3,较治疗前增大(1.21±0.31) mm3,差异有统计学意义(t=3.237,P<0.05),PRP术后3个月MCV值为(6.11±0.57) mm3,较治疗前减小(0.87±0.22) mm3,差异有统计学意义(t=3.305,P<0.05)。结论：黄斑区格栅激光后1周及PRP术后1个月DR患者MCV值增大,3个月MCV值减小。OCT-EDI可以无创地、直观地观察到黄斑区脉络膜结构的变化。     

Evaluation of pharyngeal shape and size using anatomical optical coherence tomography in individuals with and without obstructive sleep apnoea

This study compared shape, size and length of the pharyngeal airway in individuals with and without obstructive sleep apnoea (OSA) using a novel endoscopic imaging technique, anatomical optical coherence tomography (aOCT). The study population comprised a preliminary study group of 20 OSA patients and a subsequent controlled study group of 10 OSA patients and 10 body mass index (BMI)-, gender- and age-matched control subjects without OSA. All subjects were scanned using aOCT while awake, supine and breathing quietly. Measurements of airway cross-sectional area (CSA) and anteroposterior (A-P) and lateral diameters were obtained from the hypo-, oro- and velopharyngeal regions. A-P : lateral diameter ratios were calculated to provide an index of regional airway shape. In all subjects, pharyngeal CSA was lowest in the velopharynx. Patients with OSA had a smaller velopharyngeal CSA than controls (maximum CSA 91 +/- 40 versus 153 +/- 84 mm(2); P < 0.05) but comparable oro- (318 +/- 80 versus 279 +/- 129 mm(2); P = 0.48) and hypopharyngeal CSA (250 +/- 105 versus 303 +/- 112 mm(2); P = 0.36). In each pharyngeal region, the long axis of the airway was oriented in the lateral diameter. Airway shape was not different between the groups. Pharyngeal airway length was similar in both groups, although the OSA group had longer uvulae than the control group (16.8 +/- 6.2 versus 11.2 +/- 5.2 mm; P < 0.05). This study has shown that individuals with OSA have a smaller velopharyngeal CSA than BMI-, gender- and age-matched control volunteers, but comparable shape: a laterally oriented ellipse. These findings suggest that it is an abnormality in size rather than shape that is the more important anatomical predictor of OSA.     

眼前段光学相干断层扫描仪与超声生物显微镜测量中央前房深度的比较

目的 比较眼前段光学相干断层扫描仪(AS-OCT)与超声生物显微镜(UBM)测量中央前房深度(ACD)的差异和两者的可重复性.方法 分别用AS-OCT和UBM测量急性原发性闭角型青光眼(APACG)患者29例55眼(发作眼32眼,未发作眼23眼),慢性原发性闭角型青光眼(CPACG)患者4l例74眼的ACD.采用配对t检验进行不同仪器ACD测量值比较;相关分析法分析两种仪器测量值之间的相关性.完全随机法选择1只眼分别用AS-OCT和UBM依次重复测量ACD 10次,比较测量的可重复性.结果 APACG发作眼用AS-OCT测量的ACD值与UBM的测量值之间差异无统计学意义.APACG对侧眼、CPACG眼的AS-OCT测量值比UBM测量值大[(1.923+0.287)mm比(1.860±0.243)mm,(2.017±0.054)mm比(1.913±0.052)mm,均P=0.012].AS-OCT和UBM的ACD测量值呈正相关(r=0.928,P<0.001).AS-OCT与UBM测量ACD的变异系数分别为0.66%和0.82%.结论 AS-OCT比UBM测量的ACD值大,两种仪器测量值相关性良好.AA-OCT的可重复性优于UBM.     

早期自然釉质龋光学相干断层图像定量分析

目的 通过对早期自然龋变光学相干断层成像(OCT)图像进行定量分析,寻找适于光学相干断层成像技术检测早期龋的定量参数指标.方法 选取D0期、D1期和D2期自然发生釉质龋双尖牙标本各3颗,利用光学相干断层成像分别对上述不同程度早期釉质龋人离体牙进行扫描,并以龋变区域(目标区域)平均灰度值与正常区域(背景区域)平均灰度之比...     

Identification of vulnerable plaque in a stented coronary segment 17 years after implantation using optical coherence tomography

A patient presented with exertional chest pain two months prior to admission. Coronary angiography revealed a subocclusive stenosis within the boundaries of the stent. Optical coherence tomography showed remarkable intimal growth inside the stent, which demonstrated a heterogeneous appearance including low-intensity areas. These findings were congruent with the morphology of fibroatheroma in the native coronary artery and suggested that new atherosclerotic progression of the intima within the stent had occurred over 17 years following bare metal stent implantation. To the best of our knowledge, this is one of the most delayed instances of a bare metal stent restenosis described in the medical literature.     

利用光学相干断层图像平均灰度值定量研究牛恒牙早期人工脱矿

目的 研究经酸蚀脱矿后牛恒牙光学相干断层图像平均灰度值的变化,探讨平均灰度值作为一个参数指标定量检测牛恒牙早期脱矿的可行性.方法 以正常离体牛恒牙为样本,采用凝胶酸蚀法制备人工脱矿模型;用光学相干断层摄影术对人工脱矿模型扫描成像,利用Matlab软件计算不同酸蚀时间脱矿区牙体层110 μm范围内的平均灰度值.将测得图像灰度和归一化后图像灰度,分别进行单因素方差分析.结果 牙体表层110 μm范围内不同时间酸蚀脱矿区的平均灰度值从大到小依次为30 min酸蚀脱矿区、1O min酸蚀脱矿区、0 min酸蚀脱矿区,图像灰度归一化后做单因素方差分析,P＜0.05.结论 牙体表层110 μm范围内不同酸蚀时间脱矿区平均灰度值差异有统计学意义,并随脱矿时间增加而增大,即平均灰度值可以用于光学相干断层摄影术定量检测牙齿的早期脱矿.光学相干断层图像灰度归一化使得不同酸蚀脱矿区的平均灰度值更有可比性,减小了由于样本之间差异引起的误差,提高了平均灰度值作为参数指标定量检测牙齿早期脱矿的可靠性.     

Optical coherence tomography imaging of the basal ganglia: feasibility and brief review

Optical coherence tomography (OCT) is a promising medical imaging technique that useslight to capture real-time cross-sectional images from biological tissues inmicrometer resolution. Commercially available optical coherence tomography systemsare employed in diverse applications, including art conservation and diagnosticmedicine, notably in cardiology and ophthalmology. Application of this technology inthe brain may enable distinction between white matter and gray matter, and obtainmentof detailed images from within the encephalon. We present, herein, the invivo implementation of OCT imaging in the rat brain striatum. For this,two male 60-day-old rats (Rattus norvegicus, Albinus variation,Wistar) were stereotactically implanted with guide cannulas into the striatum toguide a 2.7-French diameter high-definition OCT imaging catheter (Dragonfly™, St.Jude Medical, USA). Obtained images were compared with corresponding histologicallystained sections to collect imaging samples. A brief analysis of OCT technology andits current applications is also reported, as well as intra-cerebral OCT feasibilityon brain mapping during neurosurgical procedures.     

Three-dimensional diffuse optical tomography in the parallel plane transmission geometry: evaluation of a hybrid frequency domain/continuous wave clinical system for breast imaging

Three-dimensional diffuse optical tomography (DOT) of breast requires large data sets for even modest resolution (1 cm). We present a hybrid DOT system that combines a limited number of frequency domain (FD) measurements with a large set of continuous wave (cw) measurements. The FD measurements are used to quantitatively determine tissue averaged absorption and scattering coefficients. The larger cw data sets (10(5) measurements) collected with a lens coupled CCD, permit 3D DOT reconstructions of a 1-liter tissue volume. To address the computational complexity of large data sets and 3D volumes we employ finite difference based reconstructions computed in parallel. Tissue phantom measurements evaluate imaging performance. The tests include the following: point spread function measures of resolution, characterization of the size and contrast of single objects, field of view measurements and spectral characterization of constituent concentrations. We also report in vivo measurements. Average tissue optical properties of a healthy breast are used to deduce oxy- and deoxy-hemoglobin concentrations. Differential imaging with a tumor simulating target adhered to the surface of a healthy breast evaluates the influence of physiologic fluctuations on image noise. This tomography system provides robust, quantitative, full 3D image reconstructions with the advantages of high data throughput, single detector-tissue coupling path, and large (1L) imaging domains. In addition, we find that point spread function measurements provide a useful and comprehensive representation of system performance.     

Design of electrodes and current limits for low frequency electrical impedance tomography of the brain

For the novel application of recording of resistivity changes related to neuronal depolarization in the brain with electrical impedance tomography, optimal recording is with applied currents below 100 Hz, which might cause neural stimulation of skin or underlying brain. The purpose of this work was to develop a method for application of low frequency currents to the scalp, which delivered the maximum current without significant stimulation of skin or underlying brain. We propose a recessed electrode design which enabled current injection with an acceptable skin sensation to be increased from 100 μA using EEG electrodes, to 1 mA in 16 normal volunteers. The effect of current delivered to the brain was assessed with an anatomically realistic finite element model of the adult head. The modelled peak cerebral current density was 0.3 A/m², which was 5 to 25-fold less than the threshold for stimulation of the brain estimated from literature review.     

人工晶状体植入治疗白内障后准分子激光上皮下角膜磨镶矫治的安全性

背景：白内障摘除联合人工晶状体植入部分患者晶状体植入后依然存在不同程度屈光不正现象,可以采用准分子激光上皮下角膜磨镶或准分子激光原位角膜磨镶矫正屈光不正。 目的：观察应用准分子激光上皮下角膜磨镶矫治白内障摘除联合人工晶状体植入后残留屈光不正的效果。 方法：纳入白内障摘除联合人工晶状体植入后残留屈光不正38例(45眼),其中男22例,女16例;年龄24-74岁;角膜中央厚度490-590 μm,准分子激光上皮下角膜磨镶前裸眼视力为0.1-0.3,矫正视力为0.6-1.0。均应用准分子激光上皮下角膜磨镶进行矫治,术后随访12个月,观察裸眼视力、最佳矫正视力、屈光度、眼压等情况。 结果与结论：大部分患者于术后3-6 h后有异物感、疼痛等眼部刺激症状,术后2 d内有不同程度的眼痛、畏光、流泪等角膜刺激症状,术后7 d左右角膜上皮基本愈合,20 d左右视力基本恢复到最佳。术后12个月时裸眼视力均≥0.6,其中26眼视力达到或超过1.0(58%),35眼(78%)术后裸眼视力达到或超过术前最佳矫正视力。术后12个月裸眼视力为0.6-1.2。球镜度数从术前平均-2.5 m^-1降至术后-0.5 m^-1,柱镜度数从术前平均-3.85 m^-1降至术后-0.53 m^-1。12眼发生眼压偏高,5眼有0.5级角膜上皮下雾状混浊形成。结果说明准分子激光上皮下角膜磨镶治疗白内障摘除联合人工晶状体植入后屈光不正是安全有效的。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

The potential for non‐invasive study of mummies: validation of the use of computerized tomography by post factum dissection and histological examination of a 17th century female Korean mummy

The socio‐cultural antipathies of some descendants with regard to invasive examinations of age‐old human remains make permission for dissection of Korean mummies of the Joseon Dynasty (1392–1910) difficult to obtain. Overcoming this obstacle necessitated the use of non‐invasive techniques, such as multi‐detector computerized tomography (MDCT) and endoscopic examination, enabling determination of the preservation status of internal organs of mummies without significantly damaging the mummies themselves. However, MDCT alone cannot clearly differentiate specific mummified organs. Therefore, in much the same way as diagnostic radiologists make their MDCT readings on living patients more reliable by means of comparison with accumulated post‐factum data from autopsies or histological studies, examinations of mummies by invasive techniques should not be decried as mere destruction of age‐old human remains. Rather, providing that due permission from descendants and/or other relevant authorities can be obtained, dissection and histological examination should be performed whenever opportunities arise. Therefore, in this study, we compared the radiological data acquired from a 17th century mummy with our dissection results for the same subject. As accumulation of this kind of data could be very crucial for correct interpretation of MDCT findings on Korean mummies, we will perform similar trials on other Korean mummies found in forthcoming days if conditions permit.