Speckle contrast diffuse correlation tomography of complex turbid medium flow

• Published in: Medical physics (Lancaster) Vol. 42; no. 7; pp. 4000 - 4006
• Main Authors: Huang, Chong, Irwin, Daniel, Lin, Yu, Shang, Yu, He, Lian, Kong, Weikai, Luo, Jia, Yu, Guoqiang
• Format: Journal Article
• Language: English
• Published: United States American Association of Physicists in Medicine 01.07.2015
• Subjects: ALGORITHMS; Biological material, e.g. blood, urine; Haemocytometers; biological tissues; biomedical optical imaging; bio‐optics; blood flow; CCD image sensors; Charge coupled imagers; CHARGE-COUPLED DEVICES; Computer Simulation; COMPUTERIZED SIMULATION; COMPUTERIZED TOMOGRAPHY; CONTRAST MEDIA; CORRECTIONS; DATA ACQUISITION; diffuse correlation tomography (DCT); Digital computing or data processing equipment or methods, specially adapted for specific applications; Equipment Design; finite element analysis; Finite element calculations; finite element method (FEM); Finite element methods; Finite‐element and Galerkin methods; Flow visualization; haemodynamics; Hemodynamics; Humans; Image data processing or generation, in general; IMAGE PROCESSING; image reconstruction; Imaging, Three-Dimensional - instrumentation; Imaging, Three-Dimensional - methods; INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; laser applications in medicine; Laser imaging; Lasers; LIQUIDS; Medical image contrast; medical image processing; Medical Physics Letter; Models, Biological; OPTICAL PROPERTIES; optical switches; optical tomography; PHANTOMS; Phantoms, Imaging; Reconstruction; Speckle; speckle contrast; Tissues; Tomography; Tomography - instrumentation; Tomography - methods
• ISSN: 0094-2405; 2473-4209; 2473-4209
• DOI: 10.1118/1.4922206

Purpose: Developed herein is a three‐dimensional (3D) flow contrast imaging system leveraging advancements in the extension of laser speckle contrast imaging theories to deep tissues along with our recently developed finite‐element diffuse correlation tomography (DCT) reconstruction scheme. This technique, termed speckle contrast diffuse correlation tomography (scDCT), enables incorporation of complex optical property heterogeneities and sample boundaries. When combined with a reflectance‐based design, this system facilitates a rapid segue into flow contrast imaging of larger, in vivo applications such as humans. Methods: A highly sensitive CCD camera was integrated into a reflectance‐based optical system. Four long‐coherence laser source positions were coupled to an optical switch for sequencing of tomographic data acquisition providing multiple projections through the sample. This system was investigated through incorporation of liquid and solid tissue‐like phantoms exhibiting optical properties and flow characteristics typical of human tissues. Computer simulations were also performed for comparisons. A uniquely encountered smear correction algorithm was employed to correct point‐source illumination contributions during image capture with the frame‐transfer CCD and reflectance setup. Results: Measurements with scDCT on a homogeneous liquid phantom showed that speckle contrast‐based deep flow indices were within 12% of those from standard DCT. Inclusion of a solid phantom submerged below the liquid phantom surface allowed for heterogeneity detection and validation. The heterogeneity was identified successfully by reconstructed 3D flow contrast tomography with scDCT. The heterogeneity center and dimensions and averaged relative flow (within 3%) and localization were in agreement with actuality and computer simulations, respectively. Conclusions: A custom cost‐effective CCD‐based reflectance 3D flow imaging system demonstrated rapid acquisition of dense boundary data and, with further studies, a high potential for translatability to real tissues with arbitrary boundaries. A requisite correction was also found for measurements in the fashion of scDCT to recover accurate speckle contrast of deep tissues.