生物醫(yī)學(xué)光子學(xué)與激光散斑成像科學(xué)探究

1、Laser Speckle Contrast ImagingTheory, Instrumentation and ApplicationsDepartment of Biomedical EngineeringLab of Biomedical PhotonicsBiomedical Optics Topic第1頁1 May Page2Introduction to Biomedical Optics Diffuse Optical Tomography (DOT) Photoacoustic Imaging (PAI) Multi-spectral Optical Intrinsic Si

2、gnal Imaging Molecular Imaging Ultrafast Photography High Resolution Altas of Mouse Brain Laser Speckle Contrast Imaging Theory Instrumentation ApplicationsOuline第2頁1 May Page3General optics theoryTherapeutic applications of lightDiagnostic optical methods Medical optical imaging is the use of light

3、 as an investigational imaging technique for medical applications.Biomedical Optics第3頁1 May Page4Diffuse Optical Tomography (DOT)Nat Photonics. June ; 8(6):第4頁1 May Page5Diffuse Optical Tomography (DOT)第5頁1 May Page6Photoacoustic Imaging (PAI)第6頁1 May Page7Photoacoustic Imaging (PAI)第7頁1 May Page8Ph

4、otoacoustic Imaging (PAI)第8頁1 May Page9Multi-spectral Optical Intrinsic Signal Imaging第9頁1 May Page10Multi-spectral Optical Intrinsic Signal ImagingSimultaneous detection of hemodynamics, mitochondrial metabolism and light scattering changes during cortical spreading depression in rats based on mult

5、i-sNeuroImageVolume 76, 1 August , Pages 7080第10頁1 May Page11Molecular imagingMarina V Backer, NATURE MEDICINE , 13第11頁1 May Page12Molecular imagingW.T. Li, BIOMEDICAL OPTICS EXPRESS, , 2679L.M. Nie, ACS Nano, 第12頁1 May Page13Molecular imagingIn vivo photoacoustic imaging of brain injury and rehabil

6、itation by NIR dye labeled mesenchymal stem cells with enhanced brain barrier permeabilityWeitao Li, #, Hongke Wang, , #, Jing Lv, #, Ronghe Chen, Yu Liu, Ya Peng, and Liming Nie, *第13頁1 May Page14Ultrafast Photography L Gao et al. Nature 516, 74-77 ()第14頁1 May Page15Ultrafast Photography high speed

7、 digital image sequence第15頁1 May Page16High Resolution Altas of Mouse Brain第16頁1 May Page17High Resolution Altas of Mouse Brain Li A, , Science, 330(6009)第17頁1 May Page18Laser Speckle Contrast Imaging Theory Instrumentation ApplicationsOuline第18頁1 May Page19What is laser speckle contrast imaging?J.

8、Senarathna, IEEE Reviews in Biomedical Engineering, 6, 第19頁1 May Page20When coherent light scatters from a random medium, the scattered light produces a random interference pattern called speckle.Speckle Definition* D.A. Boas, Journal of Biomedical Optics, , 15(1)# D. Briers, Journal of Biomedical O

9、ptics, , 18(6)第20頁1 May Page21SpeckleJ. Senarathna, IEEE REVIEWS IN BIOMEDICAL ENGINEERING, 6, 第21頁1 May Page22The theoretical basis for analyzing speckle intensity fluctuations dates back to the late 1960s with the development of dynamic light scattering.History-1960R. Pecora, Annual Review of Biop

10、hysics and Bioengineering, 1972第22頁1 May Page23There was extensive activity in the 1970s rigorously relating speckle temporal dynamics to various forms of particle dynamics in dilute single-scattering suspensions.History-1970In vivo evaluation of microcirculation by coherent light scatteringNature 2

11、54, 56 - 58 (06 March 1975)第23頁1 May Page24A solution was presented in the 1980s using a camera to obtain a quick snapshot image of a time-integrated speckle pattern,History-1980A. Fercher, Optics Communications 37(5), 1981第24頁1 May Page25This method, laser speckle contrast imaging (LSCI), was advan

12、ced in the 1990s for imaging blood flow in the retina and skin with the availability of faster digital acquisition and processing technologies.History-1990第25頁1 May Page26The speckle image of 2-D maps of blood flow can be obtained with very high spatial and temporal resolution by using a CCD camera

13、and quantifying the spatial blurring of the speckle pattern.To quantify the blurring of the speckles, the speckle contrast, defined as the ratio of the standard deviation to the mean intensity, is computed as,Theoretical BackgroundNote that we use s to refer to the spatial standard deviation of the

14、speckle intensity, K is the spatial speckle contrast, and is the average intensity of speckle image.第26頁1 May Page27激光散斑襯比成像基本原理第27頁1 May Page28This gives a speckle contrastTheoretical Background第28頁1 May Page29Modulate of LSCI(a) Spatial Speckle Contrast(b) Temporal Speckle Contrast(c) Spatial vers

15、us Temporal Speckle Contrast第29頁1 May Page30激光散斑空間襯比分析如圖所表示，圖中每個(gè)方格代表一個(gè) CCD圖像上像素點(diǎn)，第一個(gè) NsNs 方框中像素點(diǎn)襯比值賦給中央點(diǎn)，方框右移一個(gè)像素點(diǎn)。如此循環(huán)，以此對(duì)全部區(qū)域進(jìn)行一樣運(yùn)算，最終獲得各個(gè)區(qū)域襯比值。計(jì)算空間襯比流程示意圖第30頁1 May Page31激光散斑時(shí)間襯比分析計(jì)算時(shí)間襯比流程示意圖如圖所表示，對(duì)這一系列圖片空間上每一個(gè)像素都對(duì)應(yīng)有一個(gè)光強(qiáng)改變時(shí)間序列，對(duì)這一個(gè)時(shí)間序列進(jìn)行時(shí)間襯比統(tǒng)計(jì)，則取得該點(diǎn)時(shí)間襯比，類似于對(duì)空間上每一個(gè)像素點(diǎn)做類似處理。第31頁1 May Page32激光散斑空間襯比

16、分析計(jì)算時(shí)空襯比流程示意圖基于時(shí)間和空間襯比分析方法，衍生出各種將空間與時(shí)間統(tǒng)計(jì)相結(jié)合襯比分析方法。總體思緒如圖所表示，對(duì)NsNsNt個(gè)像素統(tǒng)計(jì)第32頁1 May Page33激光散斑襯比分析方法空間襯比K值圖時(shí)間襯比K值圖時(shí)空襯比K值圖第33頁1 May Page34Instrumentationlaser light in the wavelength range of 600 nm to 900 nma 10 bit or higher resolution CCD camera: exposure times may range from 1 ms to 20 ms; frame ra

17、tes in the order of 10 to 30 frames per second.第34頁1 May Page35Laser SourceContinuous waveLower powerLinear polorized light632.8 He-Ne laser3 mW, SPL-HN250R, Hangzhou SPL Photonics, China第35頁1 May Page36Then the laser passes an expander and irradiates the imaging region with a diameter of 12 mm and

18、the incident angle of 30-45。Light path第36頁1 May Page37a zoom stereo microscope (50486A, Navitar, USA) a monochrome 12 bit CCD camera (GS3-U3-51S5M-C, Point Grey, Canada) with 24482048 pixels, yielding an image of 1.57 mm 18.97 mm depending on the magnification with 0.58 - 7.0. The exposure time of t

19、he CCD was 15 ms. Images were acquired through the programming software at 20 Hz.Magnitude and CCD第37頁1 May Page38LSCI system in our lab第38頁1 May Page39圖左. 7激光散斑測(cè)得大腦血流改變圖A、B、C、D、E分別代表急性酒精注射前、注射后20分鐘、40分鐘、60分鐘、80分鐘時(shí)刻大腦局部血流偽彩圖，F(xiàn)為白光照射下拍攝原始圖片；圖中使用紅色矩形框標(biāo)示出感興趣區(qū)域。激光散斑成像血流圖急性飲酒試驗(yàn)圖右. 激光散斑測(cè)得ROI區(qū)域大腦血流改變CBF圖第39

20、頁1 May Page40激光散斑襯比成像研究趨勢(shì)成像參數(shù)的研究成像方式的研究成像方法的應(yīng)用第40頁1 May Page41激光散斑襯比成像參數(shù)研究 散斑大小研究Dunn proposed Here, is the diameter of the speckle Airy disc, is the wavelength, is the magnification and the f-number is the ratio of focal length to aperture diameter. Kirkpatrick et al. showed that speckle sizes belo

21、w twice the pixel size cause the speckle contrast to severely. Therefore, a speckle size of twice the pixel size is considered optimal. 第41頁1 May Page42曝光時(shí)間研究Effect of camera exposure time Speckle contrast images at six separate exposures exhibiting increased speckle visibility (e.g., contrast) at l

22、ower exposures and highlighting varying flow range sensitivity with exposure selection.The overall effect of exposure time on a set of normalized laser speckle contrast images. Smaller vessels become more visible as the exposure time increases, but simultaneously, the effect of increasing image nois

23、e becomes evident. 第42頁1 May Page43激光散斑襯比成像研究趨勢(shì)成像參數(shù)的研究成像方式的研究成像方法的應(yīng)用第43頁1 May Page44便攜式激光散斑成像系統(tǒng)第44頁1 May Page45光纖內(nèi)窺視激光散斑成像系統(tǒng)a: The fiber-based LSI probe is composed of a leached fiber bundle with a lens at one end. The fiber bundle directs light through a 4 objective to the camera sensor. b: A custo

24、m-built adjustable lens holder contains a 2 mm drum lens. The imaging fiber fits through a hole down the center of the metal and plastic pieces. The plastic end rotates to allow for fine focusing by adjusting the distance between the end of the fiber bundle and the drum lens. c: The imaging fiber bu

25、ndle (black) is placed 50 mm from the subject. The laser fiber (blue) transmits laser light into the mouth, to the lingual side of the tooth. d: The laser fiber (blue) is coupled with an SMA adapter to the retroreflector (black). This component contains two right-angle prisms (white) to redirect the

26、 light towards the lingual side of the tooth hence towards the imaging fiber bundle.第45頁1 May Page46多模式光學(xué)聯(lián)合電生理統(tǒng)計(jì)系統(tǒng)Schematic representation of experimental setup and strategy for multimodal optical imaging. (a): Diagram of instruments used for detections of fluorescence signal, dual-wavelength OISs a

27、nd blood velocity. Coupling of fluorescence imaging and dual-wavelength OISI was achieved with time-sharing CCD1 by alternating the center wavelength of LCTF. LSCI was accomplished by LD illumination and raw speckle images were continuously acquired by CCD2. Synchronization of the two CCD was achiev

28、ed by a signal delivered from PC1. (b): Timing charts of fluorescence imaging and dual-wavelength OISI by CCD1. 第46頁1 May Page47激光散斑襯比成像研究趨勢(shì)成像參數(shù)的研究成像方式的研究成像方法的應(yīng)用與發(fā)展第47頁1 May Page48(A) Laser speckle contrast imaging (LSCI) estimated perfusion (left; from low perfusion in black to high perfusion in re

29、d), intensity (middle) and picture (right) on the forearm. Regions of interests (ROIs) were adjacent to the LDF probes (numbered 13) and within the SHP3 heating probe (4). (B) Flux pattern recorded with LSCI for the 4 ROIs during the five periods analyzed: baseline before post-occlusive hyperemia (P

30、ORH BL), PORH peak (PORH PK), baseline before LTH (LTH BL), LTH peak (LTH PK) and LTH plateau. PU: perfusion units.LDF 和LSCI 結(jié)合皮膚灌注研究 第48頁1 May Page49Sample images generated from a typical burn scar showing a hypertrophic scar surrounded by normal skin: (a) LSPI CCD camera photograph; (b) LSPI perfusion image; (c) Moor LDI total reflected light intensity map; (d) Moor LDI perfusion map.LSCI用于皮膚傷疤研究第49頁1 May Page50LSI blood-flow index and percent-change maps of a rat retina. LSI was performed while the animal was breathing air or oxygen. Percent change maps are the differences between oxy