Kijoon Lee

Daegu Gyeongbuk Institute of Science and Technology | DGIST · Department of Information and Communication Engineering

Background and Objective Diffuse correlation spectroscopy (DCS) is an optical technique widely used to monitor blood flow. Recently, efforts have been made to derive new signal processing methods to minimize the systems used and shorten the signal processing time. Herein, we propose alternative approaches to obtain blood flow information via DCS by...

This data article reports the level of expression of messenger RNA (mRNA) obtained from a set of 18 skeletal muscle samples using Affymetrix Genechips Exon arrays. Data were obtained from Gastrocnemius muscle of C57BL6 male mice at 3 distinct age groups, 2, 11 and 25 months old representing young, mature adult and aged groups. The data submitted to...

An angiosome refers to a 3D tissue volume that is vascularized by a single artery and is a relatively new concept that is useful in vascular surgery; however, the direct relationship between arterial blood flow and micro-perfusion is still controversial. Here, we propose a diffuse speckle contrast analysis (DSCA), which is an emerging tissue perfus...

Assessing blood flow, as well as blood volume and oxygen saturation, is of utmost importance for health monitoring. Assessing microcirculation, as opposed to macrocirculation, is especially important for assessing the local tissue viability. Many optics-based modalities have been developed recently such as laser speckle contrast imaging (LSCI), las...

This chapter introduces two popular laser‐speckle‐based methods, laser speckle contrast imaging (LSCI) and diffuse speckle contrast analysis (DSCA) for skin blood circulation characterization. LSCI images skin blood perfusion with large field of view but limited penetration depth. DSCA is a point measurement method that probes deep into the tissue....

[This corrects the article DOI: 10.18632/oncotarget.15720.].

We propose a novel application of diffuse correlation spectroscopy to evaluate microvascular malfunctions of muscle tissue affected by hyperglycemia and determine their correlation with the severity of diabetic neuropathy at a later stage. Microvascular responses of the thigh muscle and the mechanical pain threshold of the hind paw of streptozotoci...

Blood oxygenation and flow are both important parameters in a living body. In this Letter, we introduce a simple configuration to simultaneously measure blood flow and oxygenation using an off-the-shelf spectrometer. With the integration time of 10 ms, flow phantom measurements, a liquid blood phantom test, and an arm cuff occlusion paradigm were p...

An angiosome is a three dimensional volume of biological tissue which a specific artery governs. Although proven useful for vascular surgery, the direct relationship between arterial flow and microcirculation in specific angiosome remains controversial. Here, we present new optical approach, a four-channel diffuse speckle contrast analysis (DSCA) w...

Photodynamic therapy (PDT) of cancer involves the use of a photosensitizer that can be light-activated to eradicate tumors via direct cytotoxicity, damage to tumor vasculature and stimulating the body's immune system. Treatment outcome may vary between individuals even under the same regime; therefore a non-invasive tumor response monitoring system...

Purpose: The authors introduce a state-of-the-art all-optical clinical diffuse optical tomography (DOT) imaging instrument which collects spatially dense, multispectral, frequency-domain breast data in the parallel-plate geometry. Methods: The instrument utilizes a CCD-based heterodyne detection scheme that permits massively parallel detection o...

A combined diffuse speckle contrast analysis (DSCA)-near-infrared spectroscopy (NIRS) system is proposed to simultaneously measure qualitative blood flow and blood oxygenation changes in human tissue. The system employs an optical switch to alternate two laser sources at two different wavelengths and a CCD camera to capture the speckle image. There...

Determining the survival rate of avian embryos during incubation is essential for cost-saving in the poultry industry. A multi-channel diffuse speckle contrast analysis (DSCA) system, comprising four optical fiber channels, is proposed to achieve noninvasive in vivo measurements of deep tissue flow. The system was able to monitor chick embryo vital...

To see what is happening under our skin using light would have been a dream, as there are many strong absorbers and scatterers that act as hindrances for imaging purpose. Although light penetrates the skin a little and it is possible to image and monitor superficial blood flow using light illumination, it remains as a challenge to probe deep tissue...

In poultry industry which is avian breeding program, the determination whether chick embryos survive in the artificial incubation periods or not is essential to reduce the financial resources. We developed the multi-channel diffuse speckle contrast analysis (DSCA) system composed of four optical fiber detectors enabling to achieve in-vivo measureme...

Appropriate oxygen supply and blood flow are important in coordination of body functions and maintaining a life. To measure both oxygen supply and blood flow simultaneously, we developed a system that combined near-infrared spectroscopy (NIRS) and diffuse speckle contrast analysis (DSCA). Our system is more cost effective and compact than such comb...

Blood perfusion in human tissue can be measured in vivo by means of various optical methods, which seem to be very different from one another. The most prominent examples of them are laser Doppler flowmetry, laser speckle contrast imaging, diffuse correlation spectroscopy, and the most recently developed diffuse speckle contrast analysis. In this p...

Tumor response during photodynamic therapy (PDT) is heavily dependent on treatment parameters such as light dose, photosensitizer concentration, and tissue oxygenation. Therefore, it is desirable to have a real-time hemodynamic monitoring device in order to fine-tune the parameters and improve PDT efficacy. In this paper, such a tumor response moni...

The age-related loss of skeletal muscle mass and function (sarcopenia) is a consistent hallmark of ageing. Apoptosis plays an important role in muscle atrophy, and the intent of this study was to specify whether apoptosis is restricted to myofibre nuclei (myonuclei) or occurs in satellite cells or stromal cells of extracellular matrix (ECM). Sarcop...

Assessing the level of microcirculation on the human body is of paramount importance in clinics because direct measurement of blood perfusion gives information about tissue viability at specific locations. Large-vessel blood flow (macrocirculation), measured by duplex ultrasound or angiograph, does not tell us whether or not the wound will heal.

Photodynamic therapy (PDT) of cancer works via direct cytotoxicity, causing damage to tumor vasculature and stimulating the body's anti-tumor immune response. PDT outcome depends on the parameters used; therefore an in vivo tumor response monitoring system is useful for optimization of the treatment protocol. The combined use of diffuse optical spe...

Recently, diffuse speckle contrast analysis (DSCA) was introduced as a competent modality for deep tissue blood flow measurement, where the speckle contrast is calculated over spatial domain on the CCD image of diffuse reflectance. In this paper, we introduce time-domain DSCA where temporal statistics are used for speckle contrast calculation and r...

Diffuse correlation spectroscopy (DCS) is an emerging modality for noninvasive deep tissue blood flow monitoring that is becoming increasingly popular; it conducts an autocorrelation analysis of fast fluctuating photon count signals from a single speckle. In this Letter, we show that the same level of deep tissue flow information can be obtained fr...

We applied a rigorous data mining strategy that combined principal component analysis and a clustering algorithm to analyze twenty-eight structural and compositional characteristics of mouse skeletal muscle at four different age groups: 2, 11, 22 and 25 months. First, principal component analysis was implemented to (1) optimize the data by selectin...

Diffuse correlation spectroscopy (DCS) is an emerging noninvasive technique that probes the deep tissue blood flow, by using the time-averaged intensity autocorrelation function of the fluctuating diffuse reflectance signal. We present a fast Fourier transform (FFT)-based software autocorrelator that utilizes the graphical programming language LabV...

Coherent backscattering (CBS) is a beautiful physical phenomenon that takes place in a highly scattering medium, which has potential application in noninvasive optical property measurement. The current model that explains the CBS cone shape, however, assumes the incoming beam diameter is infinitely large compared to the transport length. In this pa...

Here, we focus on assessing frontal activation of normal subjects in response to verbal fluency test. A multimodal instrument, combining NIRS and EEG, was used. The results lead to a better understanding of brain functionality.

We present an FFT-based software autocorrelator which was controlled by LabVIEW for DCS. Without much compromise in speed, the minimum decay time is in µ-second scale. Not only is it cost-effective, but also is flexible for raw signal processing.

The accurate determination of both absorption and scattering properties in homogeneous diffuse medium is critical in many applications of diffuse optical imaging, especially in clinical applications such as breast cancer diagnosis. In this paper, we report a frequency-domain method to simultaneously measure both absorption and reduced scattering co...

We present a dual modality device for both low-coherence enhanced backscattering (LEBS) measurement and optical coherence tomography (OCT). They provide complementary information with different resolutions, various applications are demonstrated.

The present study reports the design and synthesis of nine C2-symmetric 5,15-[bis(arayl)]-10α,20β-[bis(1,2:3,4-di-O-isopropylidene-α-D-galactopyranose-6-yl)]porphyrins (3–11) bearing electron donating or electron withdrawing substituents and a D2-symmetric 5α,10β,15α,20β-tetrakis(1,2:3,4-di-O-isopropylidene-α-D-galactopyranose-6-yl)porphyrin (12)....

Here, we present a mean to expand the use of individual metallic nanoparticles to two-dimensional plasmonic nanoarrays. An optical detection platform to track down localized surface plasmon resonance (LSPR) signals of individual nanoparticles on substrates was built for the application of plasmonic nanoarrays. A pseudoimage of nanoparticles on a su...

Existing imaging modalities for breast cancer screening, diagnosis and therapy monitoring, namely X-ray mammography and magnetic resonance imaging, have been proven to have limitations. Diffuse optical imaging is a set of non-invasive imaging modalities that use near-infrared light, which can be an alternative, if not replacement, to those existing...

#805 Background: Diffuse optical tomography (DOT) uses near-infrared light to non-invasively image total hemoglobin concentration and blood oxygen saturation in the human breast. Given its low cost, ease of use, and possibility of repeated measured over time, DOT is a promising adjunctive imaging modality for screening, diagnosis and monitoring of...

We use diffuse optical tomography to quantitatively reconstruct images of complex phantoms with millimeter sized features located centimeters deep within a highly-scattering medium. A non-contact instrument was employed to collect large data sets consisting of greater than 10(7) source-detector pairs. Images were reconstructed using a fast image re...

Characterization of tumor-to-normal endogenous optical contrast from 3-D diffuse optical tomography, neoadjuvant chemotherapy monitoring with additional blood flow information, and 3-D fluorescence DOT with exogenous contrast agent injection are presented.

We use diffuse optical tomography to reconstruct images of complex phantoms with subcentimeter features. A noncontact scanner collects large data sets of over 108measurements. Images are reconstructed using a fast analytic inversion formula.

We describe a Diffuse Optical Tomography breast imaging device. Frequency domain heterodyne measurements are made by modulating a laser source and detecting the transmitted light with a gain-modulated image intensifier coupled to a CCD.

We acquire and compare three-dimensional tomographic breast images of three females with suspicious masses using diffuse optical tomography (DOT) and positron emission tomography (PET). Co-registration of DOT and PET images was facilitated by a mutual information maximization algorithm. We also compared DOT and whole-body PET images of 14 patients...

We present a novel methodology for combining breast image data obtained at different times, in different geometries, and by different techniques. We combine data based on diffuse optical tomography (DOT) and magnetic resonance imaging (MRI). The software platform integrates advanced multimodal registration and segmentation algorithms, requires mini...

In this paper, we describe a novel clinical breast diffuse optical tomography (DOT) instrument for CW and RF data acquisition in transmission geometry. It is designed to be able to acquire a massive amount of data in a short amount of time available for patient measurement by using a 209-channel galvo-based fast optical switch and a fast electron-m...

Near-infrared diffuse reflectance spectroscopy (DRS) has been used to noninvasively monitor optical properties during photodynamic therapy (PDT). This technique has been extensively validated in tissue phantoms; however, validation in patients has been limited. This pilot study compares blood oxygenation and photosensitizer tissue uptake measured b...

We have developed a novel method for combining non-concurrent MR and DOT data, which integrates advanced multimodal registration and segmentation algorithms within a well-defined workflow. The method requires little user interaction, is computationally efficient for practical applications, and enables joint MR/DOT analysis. The method presents addi...

We have developed a novel method for combining non-concurrent MR and DOT data, which integrates advanced multimodal registration and segmentation algorithms within a well-defined workflow. The method requires little user interaction, is computationally efficient for practical applications, and enables joint MR/DOT analysis. The method presents addi...

We have quantified optical contrast of various tumor type (N=34) with a clinical diffuse optical tomography system. Also, we have monitored neoadjuvant chemotherapy response which agreed well with MRI.

We have acquired images of the breasts of four females with suspicious masses using Diffuse Optical Tomography and Positron Emission Tomography. The images are compared, and new types of contrast for cancer imaging are proposed.

In many DOT instrument, it is hard to generate viable reconstruction without a reference measurement. We show why the accuracy of forward model is often insufficient for absolute reconstruction, based on our transmission DOT instrument.

From in vivo three-dimensional diffuse optical tomography, the optical contrast of 30+ biopsy proven breast lesions were characterized according to mass type and correlation with demographic factors.

We use simulation and singular value analysis to optimize source-detector geometry for breast imaging in the parallel plane geometry.

We have previously presented derivation of optimum measurement wavelength sets based on unique and simultaneous recovery of chromophore concentrations and scattering coefficients.We now introduce a white light imaging setup to validate our theoretical findings.

We have measured tissue oxygenation and drug concentration using ex-vivo methods and in-vivo diffuse reflectance spectroscopy. The correlation of two methods is reported.

We have developed a software platform for multimodal integration and visualization of diffuse optical tomography and magnetic resonance imaging. Novel registration and segmentation algorithms have been integrated into the platform. The multimodal registration technique enables the alignment of non-concurrently acquired MR and DOT breast data. The n...

We have developed a software platform for multimodal integration and visualization of diffuse optical tomography (DOT) and magnetic resonance imaging (MRI) of breast cancer. The image visualization platform allows multimodality 3D image visualization and manipulation of datasets, such as a variety of 3D rendering technique, and the ability to simul...

We employ diffuse optical tomography (DOT) to track treatment progress in a female subject presenting with locally advanced invasive carcinoma of the breast during neoadjuvant chemotherapy. Three-dimensional images of total hemoglobin concentration and scattering identified the tumor. Our measurements reveal tumor shrinkage during the course of che...

We present an algorithm that explicitly utilizes the wavelength dependence of tissue optical properties for diffuse optical tomography. We have previously shown that the method gives superior separation of absorption and scattering. Here the technique is described and tested in detail, and optimum wavelength sets for a broad range of chromophore co...

Three dimensional image reconstruction from diffuse optical tomography suffers from unwanted high-frequency image noise. We show how a customized mesh and proper preprocessing steps can lead to artifact reduction and quantification improvement in reconstructed images.

We have implemented a spatially variant regularization method for nonlinear conjugate gradient (CG) based DOT that optimizes the regularization parameter without the use of Tikhonov L-curve. The regularization parameter is adjusted adaptively during CG-iterations.

Multi-spectral diffuse optical tomography was utilized for in vivo breast cancer imaging to reconstruct 3D map of chromophore concentrations and scattering directly from CW data. Blood volume contrast was found in the cancer region.

We derive conditions for unique and simultaneous recovery of chromophore concentrations and scatterering coefficients in multi-spectral CW DOT. We demonstrate a methodology for choosing optimum wavelengths, which gives superior separation of absorption and scatterering chromophores.

We calculated the group velocity of a probe pulse located at the gain center of five-level CH3F far-infrared molecular gas amplifier as a function of pump beam intensity and pressure. The results indicate this large class of optically pumped molecular system can exhibit significant group velocity reduction over a broad range of the electromagnetic...

We used a novel system based on a lower critical solution temperature (LCST) mixture containing a high gain laser dye to study laser actions in random scattering media. The LCST material comprised of hydroxypropyl cellulose (HPC) in water can be reversibly transformed from a transparent state to a highly scattering colloid as the temperature is inc...

Our system is comprised of hydroxypropyl cellulose (HPC) with a nominal average molecular weight of 370,000 dissolved in deionized water. HPC is a FDA-approved, nonionic, water-soluble cellulose derivative possessing lower critical soluble temperature (LCST) in water. When a laser dye with high gain is dissolved into this system, it makes a nice ra...

In the first half of the thesis, we investigated methods of controlling the group velocity of an optical probe pulse by another optical pulse. We focused on the gain linecenter region of an optical amplifier where group velocity can be very small due to the large dispersion. We made use of an optically pumped barium nitrate (Ba(NO3)2) Raman crystal...

The pump-induced group velocity reduction of subnanosecond pulses is calculated and measured in a Ba(NO3)2 solid-state Raman amplifier. 1.197 μm probe pulses with 90 ps duration were generated using a Raman-shifted mode-locked and Q-switched Nd:YAG laser, and propagated through a Ba(NO3)2 crystal synchronously pumped by 7-ns-long 1.06 μm pulses. Th...

Summary form only given. We report some evidence for the first time for slow pulse propagation through a transparent solid state crystal with Raman gain due to 1.06 μm pumping. This effect may possibly be used as an effective optical pulse delay generator which can be used for signals in the 1.5 μm communication band when pumped with 1.3 μm, since...