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Breast conserving surgery, in which the breast tumor and the surrounding normal tissue are removed, is the primary mode of treatment for invasive and in situ carcinomas of the breast, conditions that affect nearly 200 000 women ...
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Breast conserving surgery, in which the breast tumor and the surrounding normal tissue are removed, is the primary mode of treatment for invasive and in situ carcinomas of the breast, conditions that affect nearly 200 000 women annually. Of these nearly 200 000 patients who undergo this surgical procedure, between 20%–70% of them may undergo additional surgeries to remove tumor that was left behind in the first surgery, due to the lack of intraoperative tools that can detect whether the boundaries of the excised specimens are free from residual cancer. Optical techniques have many attractive attributes that may make them useful tools for intraoperative assessment of breast tumor resection margins. In this paper, we discuss clinical design criteria for intraoperative breast tumor margin assessment and review optical techniques applied to this problem. In addition, we report on the development and clinical testing of quantitative diffuse reflectance imaging (Q-DRI) as a potential solution to this clinical need. Q-DRI is a spectral imaging tool, which has been applied to 55 resection margins in 48 patients at Duke University Medical Center. Clear sources of contrast between cancerous and cancer-free resection margins were identified with the device, and resulted in an overall accuracy of 75% in detecting positive margins.
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Photoacoustic (PA) images utilize pulsed lasers and ultrasound transducers to visualize targets with higher optical absorption than the surrounding medium. However, they are susceptible to acoustic clutter and background noise art...
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Photoacoustic (PA) images utilize pulsed lasers and ultrasound transducers to visualize targets with higher optical absorption than the surrounding medium. However, they are susceptible to acoustic clutter and background noise artifacts that obfuscate biomedical structures of interest. We investigated three spatial-angular compounding methods to improve PA image quality for biomedical applications, implemented by combining multiple images acquired as an ultrasound probe was rotated about the elevational axis with the laser beam and target fixed. Compounding with conventional averaging was based on the pose information of each PA image, while compounding with weighted and selective averaging utilized both the pose and image content information. Weighted-average compounding enhanced PA images with the least distortion of signal size, particularly when there were large (i.e., 2.5 mm and 7 ) perturbations from the initial probe position. Selective-average compounding offered the best improvement in image quality with up 181, 1665, and 1568 times higher contrast, CNR, and SNR, respectively, compared to the mean values of individual PA images. The three presented spatial compounding methods have promising potential to enhance image quality in multiple photoacoustic applications.
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We describe the implementation of a *MATLAB experimental framework for the data conversion of magnetic-resonance (MRI) images to contrast maps. This is done for use in microwave breast cancer detection via the contrast source (CS)...
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We describe the implementation of a *MATLAB experimental framework for the data conversion of magnetic-resonance (MRI) images to contrast maps. This is done for use in microwave breast cancer detection via the contrast source (CS) model (although the underlying logic can be adapted quite easily to different contexts and applications). The framework is conceived to relieve interested developers from most of the programming burden, and to provide final users with a friendly, consistent approach to the numerical simulations.
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Deformable registration has been one of the pillars of biomedical image computing. Conventional approaches refer to the definition of a similarity criterion that, once endowed with a deformation model and a smoothness constraint, ...
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Deformable registration has been one of the pillars of biomedical image computing. Conventional approaches refer to the definition of a similarity criterion that, once endowed with a deformation model and a smoothness constraint, determines the optimal tr
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Esophageal cancer is currently the fastest growing cancer in the United States. To help combat the recent rise in morbidity, our laboratory has developed a low-cost tethered capsule endoscope system (TCE) aimed at improving early ...
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Esophageal cancer is currently the fastest growing cancer in the United States. To help combat the recent rise in morbidity, our laboratory has developed a low-cost tethered capsule endoscope system (TCE) aimed at improving early detection of esophageal cancer. The TCE contains a resonant fiberoptic laser scanner (1.6 mm O.D.) which fits into 6.4-mm easy-to-swallow capsule at the distal tip. The tethered portion contains a single mode optical fiber multiplexed to three laser diodes at the proximal end. This design offers two main advantages over current endoscope technology. First, because of its small size, the TCE can be swallowed with minimal patient discomfort, thereby obviating sedation. Second, by imaging via directed laser light, the TCE is strategically positioned to employ several burgeoning laser-based diagnostic technologies, such as narrow-band, hyperspectral, and fluorescence imaging. It is believed that the combination of such imaging techniques with novel biomarkers of dysplasia will greatly assist in identifying precancerous conditions such as Barrett''s esophagus (BE). As the probe is swallowed, the fiber scanner captures high resolution, wide-field color images of the gastroesophageal junction (500 lines at 0.05-mm resolution) currently at 15-Hz frame rate. Video images are recorded as the capsule is slowly retracted by its tether. Accompanying software generates panoramic images from the video output by mosaicing individual frames to aid in pattern recognition. This initial report describes the rationale for the unique TCE system design, results from preliminary testing in vitro and in vivo, and discussion on the merits of this new platform technology as a basis for developing a low-cost screening program for esophageal cancer.
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We present a novel method of measuring cell concentration using two electrical cell counters across a fixed control volume. Our device counts cells at the inlet and outlet of a fixed control volume and then measures the cell conce...
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We present a novel method of measuring cell concentration using two electrical cell counters across a fixed control volume. Our device counts cells at the inlet and outlet of a fixed control volume and then measures the cell concentration by calculating the number of cells in the fixed control volume. Previous methods of measuring cell concentration (such as a Coulter counter and a flow cytometer) have attempted to count cells in a given fluid volume or at a known flow rate. Thus, in spite of the miniature nature of previous devices, the accuracy of their results depends on the performance of external mechanisms such as delicate pumps and flow sensors. Our prototype, however, does not depend on accurate fluid measurement or precise control of the flow rate because it measures the number of cells in a fixed control volume. In the experimental study, we measured cell concentrations ranging from $5.8 times 10^{5}$ to $11.5 times 10^{5} hbox{cells/mL}$ without measuring or controlling the flow rate. For measuring the cell concentration, our prototype shows a maximum cell concentration measurement error of 10.3%, which is within the error range of a hemacytometer. $hfill$[2006-0127]
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In this paper, we propose and demonstrate an implantable CMOS image sensor with self-resetting pixels. The self-resetting function is implemented using a four-transistor Schmitt trigger inverter. The pixel has no counter for the n...
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In this paper, we propose and demonstrate an implantable CMOS image sensor with self-resetting pixels. The self-resetting function is implemented using a four-transistor Schmitt trigger inverter. The pixel has no counter for the number of self-resets, because the application does not require radiometric (linear) response. The pixel is fabricated using the 0.35- 2-poly 4-metal standard CMOS technology, which results in the pixel size of and a fill factor of 31%. The effective peak signal-to-noise ratio is >59 dB. An image sensor prototype comprising a pixel array is designed, and an implantable device is fabricated. As an example imaging experiment, we demonstrate blood-flow imaging of a rat-brain surface using the sensor. Intensity-change images are successfully obtained from the self-resetting pixel outputs with the image processing.
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Blood oxygenation level dependent (BOLD) contrast in functional magnetic resonance imaging (fMRI) can be enhanced using multi-echo imaging and postprocessing techniques that combine the echoes in weighted summation. Here, existing...
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Blood oxygenation level dependent (BOLD) contrast in functional magnetic resonance imaging (fMRI) can be enhanced using multi-echo imaging and postprocessing techniques that combine the echoes in weighted summation. Here, existing echo-weighting methods are reassessed in the context of an explicit physiological noise model, and a new method is introduced: weights that scale linearly with echo time. Additionally, a method using data-driven weights defined using principal component analysis (PCA) is included for comparison. Differences in BOLD contrast enhancement between methods were compared analytically where possible, and using Monte Carlo simulations for different noise conditions and different combinations of acquisition parameters. The comparisons were also validated through densely sampled (256-echo) multi-echo fMRI experimental data acquired at 1.5T and 3.0T. Results indicated that the contrast-to-noise ratio (CNR) of the studied weighting methods have a strong dependence on the physiological noise, echo spacing and the width of the sampling window. With low noise correlations between echoes, contrast gain for all weighting methods was shown to have a square root dependence on the echo sampling density, and in typical experimental noise conditions, increasing the sampling window beyond $3cdot{rm T}2^{ast}$ produced marginal additional benefit. Simulations and experiments also emphasized that noise correlations between echoes are likely the main factor limiting the potential CNR gains achievable by densely sampled multi-echo fMRI.
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This study investigates the autocorrelation bandwidths of dual-window (DW) optical coherence tomography (OCT) k-space scattering profile of different-sized microspheres and their correlation to scatterer size. A dual-bandwidth spe...
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This study investigates the autocorrelation bandwidths of dual-window (DW) optical coherence tomography (OCT) k-space scattering profile of different-sized microspheres and their correlation to scatterer size. A dual-bandwidth spectroscopic metric defined as the ratio of the 10% to 90% autocorrelation bandwidths is found to change monotonically with microsphere size and gives the best contrast enhancement for scatterer size differentiation in the resulting spectroscopic image. A simulation model supports the experimental results and revealed a tradeoff between the smallest detectable scatterer size and the maximum scatterer size in the linear range of the dual-window dual-bandwidth (DWDB) metric, which depends on the choice of the light source optical bandwidth. Spectroscopic OCT (SOCT) images of microspheres and tonsil tissue samples based on the proposed DWDB metric showed clear differentiation between different-sized scatterers as compared to those derived from conventional short-time Fourier transform metrics. The DWDB metric significantly improves the contrast in SOCT imaging and can aid the visualization and identification of dissimilar scatterer size in a sample. Potential applications include the early detection of cell nuclear changes in tissue carcinogenesis, the monitoring of healing tendons, and cell proliferation in tissue scaffolds.
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