Biomedical subjects

Huabei Jiang

Publications and source records attributed to Huabei Jiang.

At least 19 recordsLinked to original sources

PubMed2006

Quantitative reconstruction of refractive index distribution and imaging of glucose concentration by using diffusing light.

We show that a two-step reconstruction method can be adapted to improve the quantitative accuracy of the refractive index reconstruction in phase-contrast diffuse optical tomography (PCDOT). We also describe the possibility of imaging tissue glucose concentration with PCDOT. In this two-step method, we first use our existing finite-element reconstruction algorithm to recover the position and shape of a target. We then use the position and size of the target as a priori information to reconstruct a single value of the refractive index within the target and background regions using a region reconstruction method. Due to the extremely low contrast available in the refractive index reconstruction, we incorporate a data normalization scheme into the two-step reconstruction to combat the associated low signal-to-noise ratio. Through a series of phantom experiments we find that this two-step reconstruction method can considerably improve the quantitative accuracy of the refractive index reconstruction. The results show that the relative error of the reconstructed refractive index is reduced from 20% to within 1.5%. We also demonstrate the possibility of PCDOT for recovering glucose concentration using these phantom experiments.

Algorithms↗

PubMed2006

Emerging implications of nanotechnology on cancer diagnostics and therapeutics.

Nanotechnology is multidisciplinary field that involves the design and engineering of objects <500 nanometers (nm) in size. The National Cancer Institute has recognized that nanotechnology offers an extraordinary, paradigm-changing opportunity to make significant advances in cancer diagnosis and treatment. In the last several decades, nanotechnology has been studied and developed primarily for use in novel drug-delivery systems (e.g. liposomes, gelatin nanoparticles, micelles). A recent explosion in engineering and technology has led to 1) the development of many new nanoscale platforms, including quantum dots, nanoshells, gold nanoparticles, paramagnetic nanoparticles, and carbon nanotubes, and 2) improvements in traditional, lipid-based nanoscale platforms. The emerging implications of these platforms for advances in cancer diagnostics and therapeutics form the basis of this review. A widespread understanding of these new technologies is important, because they currently are being integrated into the clinical practice of oncology.

Animals↗

PubMed2006

Two-dimensional bioluminescence tomography: numerical simulations and phantom experiments.

The reconstruction of internal light sources in bioluminescence tomography (BLT) is a challenging inverse problem because of the limited amount of information available compared with that for other kinds of tomography such as fluorescence tomography in which external illumination sources are used. We demonstrated previously, using phantom experiments, that a target containing luciferases could be detected tomographically when the target was located relatively close to the imaging boundary. Here we describe an improved BLT reconstruction method that can detect luciferase-containing targets located anywhere within an imaging domain. The method is tested with numerical simulations and further confirmed with several phantom experiments.

Algorithms↗

PubMed2006

Finite-element-based photoacoustic tomography: phantom and chicken bone experiments.

We describe a photoacoustic image reconstruction algorithm that is based on the finite-element solution to the photoacoustic wave equation in the frequency domain. Our reconstruction approach is an iterative Newton method coupled with combined Marquardt and Tikhonov regularizations that can extract the spatial distribution of optical-absorption property in heterogeneous media. We demonstrate this algorithm by using phantom and chicken bone measurements from a circular scanning photoacoustic tomography system. The results obtained show that millimeter-sized phantom objects and chicken bones and/or joints can be clearly detected using our finite-element-based photoacoustic tomography method.

Algorithms↗

PubMed2006

Multispectral breast imaging using a ten-wavelength, 64 x 64 source/detector channels silicon photodiode-based diffuse optical tomography system.

We describe a compact diffuse optical tomography system specifically designed for breast imaging. The system consists of 64 silicon photodiode detectors, 64 excitation points, and 10 diode lasers in the near-infrared region, allowing multispectral, three-dimensional optical imaging of breast tissue. We also detail the system performance and optimization through a calibration procedure. The system is evaluated using tissue-like phantom experiments and an in vivo clinic experiment. Quantitative two-dimensional (2D) and three-dimensional (3D) images of absorption and reduced scattering coefficients are obtained from these experiments. The ten-wavelength spectra of the extracted reduced scattering coefficient enable quantitative morphological images to be reconstructed with this system. From the in vivo clinic experiment, functional images including deoxyhemoglobin, oxyhemoglobin, and water concentration are recovered and tumors are detected with correct size and position compared with the mammography.

Algorithms↗

PubMed2006

Spatially varying optical and acoustic property reconstruction using finite-element-based photoacoustic tomography.

A finite-element reconstruction algorithm for simultaneous reconstruction of both optical and acoustic properties of heterogeneous media is presented. The algorithm is based on the Helmholtz-like photoacoustic wave equation in the frequency domain. A dual meshing scheme is described and an adjoint sensitivity method is adopted for efficient inverse computation. The algorithm is implemented with the second-order absorbing boundary conditions and with a multireceiving and multifrequency strategy. The algorithm is evaluated using simulated data under various practical cases including different noise levels, varied range of receiving frequency, different contrast levels between the heterogeneity and background region, and multiple targets. The effect of acoustic heterogeneity on conventional pure optical absorption reconstruction is also studied.

Acoustics↗

PubMed2005

Imaging of small nanoparticle-containing objects by finite-element-based photoacoustic tomography.

We present semiquantitative photoacoustic images of small nanoparticle-containing objects having a wide range of contrast levels relative to the background. The images are obtained by a finite-element reconstruction algorithm that is based on the Helmholtz-like photoacoustic wave equation in the frequency domain. Our reconstruction approach is an iterative Newton method coupled with combined Marquardt and Tikhonov regularizations that can extract the spatial distribution of relative optical absorption property in heterogeneous media. We demonstrate experimental images in single- and multiple-object configurations with a circular scanning photoacoustic tomographic system. The results obtained show that millimeter-size nanoparticle-containing objects can be clearly detected in terms of position, size, and relative optical properties.

Acoustics↗

PubMed2005

Measurement of particle-size distribution and concentration in heterogeneous turbid media with multispectral diffuse optical tomography.

We present a method that is capable of extracting particle-size distribution (PSD) and concentration in heterogeneous turbid media by use of multispectral diffuse optical tomography (MSDOT). After the spectroscopic scattering images of the heterogeneous turbid media are obtained with MSDOT, the morphologic information of particles in the heterogeneities is recovered with an iterative regularized reconstruction algorithm based on Mie scattering theory when a particular form of PSD is assumed (Gaussian distribution is used in this study). The method described is tested and evaluated with both simulated and experimental data. The simulations are intended to test the sensitivity of the overall approach to noise effect. A series of phantom experiments are conducted with our newly developed ten-wavelength MSDOT system. Polystyrene microsphere suspensions contain particles of varying size from 2 to 6 microm as targets are embedded in a scattering background medium in these experiments. To achieve optimized results from experimental data, we developed a data preprocessing method for MSDOT as well as a scheme for calibrating scattering spectra. The results from both simulations and experiments show that the particle mean size and concentration can be reconstructed with acceptable accuracy, whereas the recovery of the standard deviation is sensitive to noise effect and can be as large as 86% from the experimental data.

Algorithms↗

PubMed2005

A practical method for three-dimensional reconstruction of joints using a C-arm system and shift-and-add algorithm.

Currently, radiography with C-arm systems is playing a major role in the assessment of arthritis. However, the radiographic two-dimensional projection images of joints often interfere with physicians' efforts to better understand and measure the structure changes of joints due to the overlap of bone structures at different depths. An accurate, low-cost, and practical three-dimensional (3D) reconstruction approach of joints will be beneficial in diagnosing arthritis. Toward this end, a novel method is developed in this paper based on a C-arm system. The idea is to apply the shift-and-add algorithm (commonly used in digital tomosynthesis) on the segmented projection images at multiple angles, which results in accurate reconstruction of the 3D structures of joints. The method provides a new solution to precisely distinguish objects from blurring background. The proposed method has been tested and evaluated on simulated cylinders, a chicken bone phantom with known structure, and an in vivo human index finger. The results are demonstrated and discussed.

Algorithms↗

PubMed2005

Ultrasound-guided microwave imaging of breast cancer: tissue phantom and pilot clinical experiments.

Microwave imaging promises high contrast between tumor and normal breast tissues, but its spatial resolution is limited. Here, we present a multimodality approach for high-resolution microwave imaging, where microwave image reconstruction is structurally guided by ultrasound imaging. The combined imaging concept is demonstrated using tissue phantom measurements obtained from a 16 x 15 transmitter/receiver microwave imaging system and a modified B-mode ultrasound system. With the geometry of the target and background known a priori from ultrasound, successful dielectric property images are recovered using a finite element-based reconstruction algorithm. We show that a target as small as 1.2 mm in diameter can be imaged with the multimodality approach, whereas it is impossible to detect such a small-size object using microwave imaging alone. The pilot clinical studies on two cases suggest that breast tumors can be much more accurately detected by the multimodality method.

Algorithms↗

PubMed2005

Model-based ultrasound tomography: tissue phantom experiments.

We present a detailed experimental study to evaluate our finite element based nonlinear reconstruction algorithm for recovery of acoustic properties in heterogeneous scattering media. Using a circularly scanning ultrasound system at 500 KHz, tissue phantom experiments were performed to study spatial resolution and contrast issues in model-based ultrasound tomography. Our results show that both acoustic attenuation and speed images can be quantitatively reconstructed in terms of the location, size, shape, and acoustic property value of the target when different contrast levels between the target and background were used. We also demonstrate that a high contrast target as small as 3 mm in diameter can be quantitatively resolved with our acoustic speed and attenuation images.

Algorithms↗

PubMed2004

Measurement of particle size distribution in mammalian cells in vitro by use of polarized light spectroscopy.

We demonstrate the feasibility of measuring the particle size distribution (PSD) of internal cell structures in vitro. We use polarized light spectroscopy to probe the internal morphology of mammalian breast cancer (MCF7) and cervical cancer (Siha) cells. We find that graphing the least-squared error versus the scatterer size provides insight into cell scattering. A nonlinear optimization scheme is used to determine the PSD iteratively. The results suggest that 2-microm particles (possibly the mitochondria) contribute most to the scattering. Other subcellular structures, such as the nucleoli and the nucleus, may also contribute significantly. We reconstruct the PSD of the mitochondria, as verified by optical microscopy. We also demonstrate the angle dependence of the PSD.

Breast Neoplasms↗

PubMed2004

Differentiation of cysts from solid tumors in the breast with diffuse optical tomography.

RATIONALE AND OBJECTIVES: Near-infrared diffuse optical tomography (DOT) is an emerging imaging technology that has the potential to offer enhanced contrast resolution over the existing technologies for detection and diagnosis of breast cancer. Thus far, the clinical evaluation of DOT has been largely limited to solid tumors. A pilot clinical study focused on DOT imaging of breasts with cysts is presented. MATERIALS AND METHODS: Six cases were studied using the recently developed compact, parallel-detection DOT system. Images characterizing the tissue absorption and scattering were obtained with a finite element-based reconstruction algorithm. The optical images were compared with the mammograms and sonograms. In one case, in vitro measurements of optical properties were conducted for the fluid obtained from needle aspiration. RESULTS: Substantial contrast between cyst and adjacent parenchyma is observed. For the six cases evaluated, the locations and sizes of cysts imaged optically are accurate and consistent with the mammographic and sonographic findings. For the case that aspiration was performed, the absorption and scattering coefficients imaged in the cyst region are quantitatively accurate compared with that measured in vitro from the fluid aspirated. CONCLUSION: This pilot study shows that cysts ranging from 1-4 cm in diameter can be quantitatively imaged. They can be differentiated from solid breast tumors because cysts generally demonstrate lower absorption and scattering coefficients compared with the surrounding normal tissue, whereas solid tumors show concurrent higher absorption and scattering related to the normal tissue.

Adult↗

PubMed2004

Model-based microwave image reconstruction: simulations and experiments.

We describe an integrated microwave imaging system that can provide spatial maps of dielectric properties of heterogeneous media with tomographically collected data. The hardware system (800-1200 MHz) was built based on a lock-in amplifier with 16 fixed antennas. The reconstruction algorithm was implemented using a Newton iterative method with combined Marquardt-Tikhonov regularizations. System performance was evaluated using heterogeneous media mimicking human breast tissue. Finite element method coupled with the Bayliss and Turkel radiation boundary conditions were applied to compute the electric field distribution in the heterogeneous media of interest. The results show that inclusions embedded in a 76-diameter background medium can be quantitatively reconstructed from both simulated and experimental data. Quantitative analysis of the microwave images obtained suggests that an inclusion of 14 mm in diameter is the smallest object that can be fully characterized presently using experimental data, while objects as small as 10 mm in diameter can be quantitatively resolved with simulated data.

Algorithms↗

PubMed2003

In vivo breast imaging with diffuse optical tomography based on higher-order diffusion equations.

We report on in vivo absorption and scattering imaging of a human breast cyst and implant, using a reconstruction algorithm based on our third-order diffusion equations. To validate these in vivo images, a series of phantom experiments were conducted, in which we used low-absorbing and low-scattering heterogeneities to mimic a breast cyst or implant. These heterogeneities or targets were composed of pure water or a mixture of water and very dilute Intralipid (0.05% and 0.1%). The phantom experiment confirmed the quantitative imaging capability of our improved algorithm for reconstructing heterogeneities where the conventional diffusion approximation is inadequate. Pilot clinical results from female volunteers indicate that enhanced diffuse optical tomography can quantitatively image findings such as breast cysts or implants in which the absorption and scattering coefficients are usually low.

Adult↗

PubMed2003

Mesh-based enhancement schemes in diffuse optical tomography.

Two mesh-based methods including dual meshing and adaptive meshing are developed to improve the finite element-based reconstruction of both absorption and scattering images of heterogeneous turbid media. The idea of dual meshing scheme is to use a fine mesh for the solution of photon propagation and a coarse mesh for the inversion of optical property distributions. The adaptive meshing method is accomplished by the automatic mesh refinement in the region of heterogeneity during reconstruction. These schemes are validated using tissue-like phantom measurements. Our results demonstrate the capabilities of the dual meshing and adaptive meshing in both qualitative and quantitative improvement of optical image reconstruction.

Algorithms↗

PubMed2003

Phase-contrast imaging of tissue using near-infrared diffusing light.

We describe a new model-based image reconstruction method that can extract the spatial variation of tissue refractive index with near-infrared diffusing light. The model of light propagation is a diffusion approximation to the radiative transfer equation for highly scattering media with spatially varying refractive index. The spatial map of refractive index is recovered using a finite element-based Newton-type reconstruction algorithm. The imaging method is validated using several tissue-like phantom experiments. Initial in vivo imaging of breast tissue is also presented, demonstrating the ability of this new imaging method for tumor detection.

Adult↗

PubMed2002

Absorption and scattering images of heterogeneous scattering media can be simultaneously reconstructed by use of dc data.

We present a carefully designed phantom experimental study aimed to provide solid evidence that both absorption and scattering images of heterogeneous scattering media can be reconstructed independently from dc data. We also study the important absorption-scattering cross-talk issue. In this regard, we develop a simple normalizing scheme that is incorporated into our nonlinear finite-element-based reconstruction algorithm. Our results from the controlled phantom experiments show that the cross talk of an absorption object appearing in scattering images can be eliminated and that the cross talk of a scattering object appearing in absorption images can be reduced considerably. In addition, these carefully designed phantom experiments clearly suggest that both absorption and scattering images can be simultaneously recovered and quantitatively separated in highly scattering media by use of dc measurements. Finally, we discuss our results in light of recent theoretical findings on nonuniqueness for dc image reconstruction.

Absorption↗