Arthur Gmitro

Arthur Gmitro
The University of Arizona | UA · Department of Radiology

About

198
Publications
10,050
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5,449
Citations
Citations since 2017
6 Research Items
1578 Citations
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2017201820192020202120222023050100150200250300
2017201820192020202120222023050100150200250300
2017201820192020202120222023050100150200250300

Publications

Publications (198)
Article
Image quality in fiber bundle-based imaging systems is inherently limited by the size and spacing of the individual fiber cores. The fiber bundle limits the achievable spatial resolution and superimposes a fixed pattern of signal variability across the image. To overcome these limitations, piezoelectric tubes were used to synchronously dither the f...
Article
Molecular probes capable of detecting colorectal cancer (CRC) are needed for early CRC diagnosis. The objective of this study was to characterize c[CTPSPFSHC]OH (TCP-1), a small peptide derived from phage display selection, for targeting human CRC xenografts using technetium-99m ((99m)Tc)-labeled TCP-1 and fluorescent cyanine-7 (Cy7)-labeled form o...
Article
Objective: The aim of this study is to evaluate the performance of a confocal fluorescence microlaparoscope for in vivo detection of ovarian cancer. Methods/materials: Seventy-one patients scheduled for open or laparoscopic oophorectomy were consented for the imaging study. High-resolution confocal microlaparoscopic images of the epithelial surf...
Article
Full-text available
A spectral imaging system was developed to study the development of breast cancer xenografts in a murine mammary window chamber model. The instrument is configured to work with either a laser to excite fluorescence or a broadband light source for diffuse reflectance imaging. Two applications were demonstrated. First, spectral imaging of fluorescenc...
Article
A theoretical analysis of the use of a fiber bundle in spectral-domain optical coherence tomography (OCT) systems is presented. The fiber bundle enables a flexible endoscopic design and provides fast, parallelized acquisition of the OCT data. However, the multimode characteristic of the fibers in the fiber bundle affects the depth sensitivity of th...
Conference Paper
Full-text available
We demonstrate for the first time optical and magnetic resonance imaging of breast cancer patient derived xenografts in an orthotopic mammary window chamber model. In vivo imaging of oxygen saturation, apparent diffusion coefficient and blood perfusion were performed.
Article
Tumor regions under hypoxic or low oxygen conditions respond less effectively to many treatment strategies, including radiation therapy. A novel investigational therapeutic, NVX-108 (NuvOx Pharma), has been developed to increase delivery of oxygen through the use of a nano-emulsion of dodecofluoropentane. By raising pO2 levels prior to delivering r...
Article
Phosphorescent lifetime imaging was employed to measure the spatial and temporal distribution of oxygen partial pressure in tissue under the coverslip of a mammary window chamber breast cancer mouse model. A thin platinum-porphyrin coating, whose phosphorescent lifetime varies monotonically with oxygen partial pressure, was applied to the coverslip...
Article
Full-text available
Confocal fluorescence microendoscopy provides high-resolution cellular-level imaging via a minimally invasive procedure, but requires fast scanning to achieve real-time imaging in vivo. Ideal confocal imaging performance is obtained with a point scanning system, but the scan rates required for in vivo biomedical imaging can be difficult to achieve....
Conference Paper
Reflectance spectroscopic imaging was used to follow blood oxygenation changes in breast cancer xenografts in mice treated with chemotherapy. The correlation between tissue perfusion, glycolytic metabolism and blood oxygenation was also investigated with nuclear and MR imaging techniques.
Conference Paper
An orthotopic mouse mammary window chamber (MWC) model has been developed for multimodal in-vivo functional and anatomical imaging of breast cancer xenografts. Capabilities to image numerous physiological aspects of the same tumor microenvironment over time has important applications such as in experiments studying the efficacies of therapeutic int...
Patent
Full-text available
The embodiments of this invention use a multi-point scanning geometry. This design maintains the high frame rate of the slit-scan system and still allows both grayscale and multi-spectral imaging. In a confocal configuration, the multi-point scanning system's confocal performance is close to that of a single point scan system and is expected to yie...
Article
Full-text available
Window chamber models have been developed and utilized as a means to study the complex microenvironment in which cancers develop, proliferate, and metastasize in small animals. Here we utilize rapid prototyping printer technology to construct a new plastic orthotopic mammary window chamber that is compatible with magnetic resonance imaging, nuclear...
Conference Paper
An achromatized miniature objective with 0.6 NA, 488 µm FOV and 2.1 magnification, built with all spherical surfaces is presented. The lens is nearly diffraction-limited over a 486 - 1000 nm spectral range for in-vivo imaging.
Conference Paper
Phosphorescent lifetime imaging of a platinum-porphyrin based coating was implemented within a mammary window chamber mouse model, allowing for spatial and temporal measurements of the partial pressure of oxygen in a breast cancer tumor environment.
Conference Paper
Cancer cells are characterized by adaptive features that allow them to evade apoptosis and proliferate in an unchecked manner in the host tissue. Therapeutic strategies often involve targeting those adaptive molecular pathways leading to downstream effects such as changes in perfusion, metabolic rate, and/or oxygen utilization in the malignant tiss...
Conference Paper
A mammary window chamber model, compatible with optical, MRI and nuclear techniques, has been developed that allows multiple imaging modalities to be employed in a single animal study and comparison of results between different modalities.
Conference Paper
Full-text available
Upregulate levels of expression and activity of membrane H+ ion pumps in cancer cells drives the extracellular pH (pHe,) to values lower than normal. Furthermore, disregulated pH is indicative of the changes in glycolytic metabolism in tumor cells and has been shown to facilitate extracellular tissue remodeling during metastasis Therefore, measurem...
Article
Window chamber models have been utilized for many years to investigate cancer development and the tumor microenvironment. Orthotopic mammary window chamber model have been developed for detailed study of breast cancer. Orthotopic window chamber models, due to the native environment, support more realistic growth and tumor behavior than ectopic mode...
Article
Ultrathin flexible fiberscopes typically have separate illumination and imaging channels and are available in diameters ranging from 0.5 to 2.5 mm. Diameters can potentially be reduced by combining the illumination and imaging paths into a single fiberoptic channel. Single-channel fiberscopes must incorporate a system to minimize Fresnel reflection...
Conference Paper
A confocal microlaparoscope for in-vivo imaging of early stage cancer inside the fallopian tube is presented. Feasibility is demonstrated using a rigid microlaparoscope and preliminary in-vivo results with the new articulating catheter are expected.
Article
Ratiometric fluorescence-imaging technique is commonly used to measure extracellular pH in tumors and surrounding tissue within a dorsal skin-fold window chamber. Using a pH-sensitive fluorophore such as carboxy SNARF-1 one can measure pH distributions with high precision. However, it is often observed that the measured pH is lower than expected, w...
Article
Recent evidence suggests that epithelial ovarian cancer may originate in the fimbriated end of the fallopian tube1. Unlike many other cancers, poor access to the ovary and fallopian tubes has limited the ability to study the progression of this deadly disease and to diagnosis it during the early stage when it is most amenable to therapy. We have pr...
Article
Full-text available
Optical biopsy facilitates in vivo disease diagnoses by providing a real-time in situ view of tissue in a clinical setting. Fluorescence confocal microendoscopy and optical coherence tomography (OCT) are two methods that have demonstrated significant potential in this context. These techniques provide complementary viewpoints. The high resolution a...
Article
Optical biopsies are aimed at providing fast and thorough screening of biological tissues in vivo . Disease diagnosis is based on the morphological structures and biochemical features of tissues that can be sampled in situ with high resolution. Some optical screening techniques, such as fluorescence confocal microendoscopy, provide a limited imagin...
Article
Optical biopsies are aimed at providing fast and thorough screening of biological tissues in vivo. Disease diagnosis is based on the morphological structures and biochemical features of tissues that can be sampled in situ with high resolution. Some optical screening techniques, such as fluorescence confocal microendoscopy, provide a limited imaging...
Article
Optical imaging and MRI have both been used extensively to study tumor microenvironment. The two imaging modalities are complementary and can be used to cross-validate one another for specific measurements. We have developed a modular platform that is capable of doing optical microscopy inside an MRI instrument. To do this, an optical relay system...
Article
Confocal microendoscopy provides real-time high resolution cellular level images via a minimally invasive procedure, but relies on exogenous fluorophores, has a relatively limited penetration depth (100 mum) and field of view (700 mum), and produces a high rate of detailed information to the user. A new catheter based multi-modal system has been de...
Article
Confocal fluorescence ratiometric imaging is an optical technique used to measure a variety of important biological parameters. A small amount of chromatic aberration in the microscope system can introduce a variation in the signal ratio dependent on the fluorophore concentration gradient along the optical axis and lead to bias in the measurement....
Article
Full-text available
Fluorescence lifetime imaging microscopy is used widely in biological research, but the accuracy and precision of lifetime measurements are limited. Photon noise is an inherent error source that cannot be eliminated. In this paper, we present a general approach to compute the probability density of the estimated lifetime for frequency-domain fluore...
Article
Slit-scanning geometries for confocal microendoscopy represent a compromise between acquisition rate and optical performance. Such systems provide high frame rates that freeze motion but recent Monte Carlo simulations show that scattered light severely limits the practical imaging depth for in vivo applications. A new multi-point scanning architect...
Article
We demonstrate the implementation of a Fourier domain optical coherence tomography (OCT) imaging system incorporated into the optical train of a fluorescence confocal microendoscope. The slit-scanning confocal system has been presented previously and achieves 3mum lateral resolution and 25mum axial resolution over a field of view of 430mum. Its mul...
Article
Slit-scanning geometries for confocal microendoscopy represent a compromise between acquisition rate and optical performance. Such systems provide high frame rates that freeze motion but recent Monte Carlo simulations show that scattered light severely limits the practical imaging depth for in vivo applications. A new multi-point scanning architect...
Conference Paper
An innovative multi-modality microendoscope is described that combines a parallelized point scanning multi-spectral confocal microendoscope with optical coherence tomography imaging. The system is intended for in-vivo diagnosis of early stage diseases. Preliminary results are provided.
Article
Confocal microendoscopy technology provides an instantaneous in vivo microscopic view of the tissue, allowing a physician to survey large areas of tissue. Confocal microendoscopes for in vivo imaging can be constructed to image backscatter of the illumination or fluorescence excited by the illumination. Bench-top fluorescence confocal microscopes c...
Conference Paper
Significant advances have been made in the design and application of confocal microendoscope systems for in vivo imaging of the human body. This presentation will review progress in the field and highlight important clinical applications.
Article
The objective of the study was to develop a clinical confocal microlaparoscope for imaging ovary epithelium in vivo with the long-term objective of diagnosing cancer in vivo. A confocal microlaparoscope was developed and used to image the ovaries of 21 patients in vivo using fluorescein sodium and acridine orange as the fluorescent contrast agents....
Article
Full-text available
We characterize and compare the axial and lateral performance of fluorescence confocal systems imaging in turbid media. The aperture configurations studied are a single pinhole, a slit, a Nipkow disk, and a linear array of pinholes. Systems with parallelized apertures are used clinically because they enable high-speed and real-time imaging. Underst...
Article
Full-text available
Successful treatment of cancer is highly dependent on the stage at which it is diagnosed. Early diagnosis, when the disease is still localized at its origin, results in very high cure rates-even for cancers that typically have poor prognosis. Biopsies are often used for diagnosis of disease. However, because biopsies are destructive, only a limited...
Article
Three-point Dixon methods have been investigated as a means to generate water and fat images without the effects of field inhomogeneities. Recently, an iterative algorithm (IDEAL, iterative decomposition of water and fat with echo asymmetry and least squares estimation) was combined with a gradient and spin-echo acquisition strategy (IDEAL-GRASE) t...
Article
The effect of peritoneal injection of acridine orange and SYTO 16 in mice was investigated. Images of peritoneal tissues stained with these dyes and obtained through a confocal micro-endoscope are presented. Seventy-five Balb/c mice were split into five groups and given peritoneal injections of dye or saline. The proportions of negative outcomes in...
Article
Window chambers implanted in mice provide a useful model system for many studies in cancer and vascular biology. A system allowing simultaneous optical and magnetic resonance imaging of window chambers is described and results presented.
Conference Paper
A new architecture for a confocal microscope is presented. The approach is a hybrid multi-point scanning system that allows real-time grayscale and multi-spectral imaging and is being developed for confocal microendoscopy.
Article
We previously reported on the development of a multi-spectral confocal laparoscope for clinical imaging. In this paper we present current results using the system to image ovaries with a new laparoscope design using the contrast agent acridine orange. This new laparoscope integrates computer controlled systems for focus, depth scans, and localized...
Conference Paper
Full-text available
The performance of most image classification algorithms deteriorates in the presence of out-of-focus blur. Thus, it is essential to either correct the focus of the input images or leave them out of the training set. There exist many focus metrics for auto-focusing, but they generally give a relative focus value. Our technique combines some of the b...
Conference Paper
Gray-level co-occurrence matrices (GLCM) are widely used for texture analysis. The number of gray-levels used while computing GLCM is an important parameter but is often ignored. It is believed that the higher the number of gray-levels used, the better is the performance of the GLCM-based features. Contrary to this belief, we observed that using mo...
Conference Paper
This paper presents the influence of photon noise in pH measurement using the fluorescence lifetime imaging microscopy. The accuracy of measurement with both frequency-domain and time-domain techniques are discussed.
Article
Full-text available
The emission and transmission properties of three commercially produced coherent fiber optic imaging bundles were evaluated. Full fluorescence excitation versus emission data were collected from 250 to 650 nm excitation for high-resolution Sumitomo, Fujikura, and Schott fiber bundles. The results generated show regions of autofluorescence and inela...
Article
Full-text available
Current electron detectors are either unable to image in vivo or lack sufficient spatial resolution because of electron scattering in thick detector materials. This study was aimed at developing a sensitive high-resolution system capable of detecting electron-emitting isotopes in vivo. The system uses a lens-coupled charge-coupled-device camera to...
Article
We describe the design and operation of a multispectral confocal microendoscope. This fiber-based fluorescence imaging system consists of a slit-scan confocal microscope coupled to an imaging catheter that is designed to be minimally invasive and allow for cellular level imaging in vivo. The system can operate in two imaging modes. The grayscale mo...
Article
To correlate the amount of bone marrow edema (BME) calculated by magnetic resonance imaging(MRI) with clinical findings, histopathology, and radiographic findings, in patients with advanced hip osteoarthritis(OA). The study was approved by The Institutional Human Subject Protection Committee. Coronal MRI of hips was acquired in 19 patients who unde...
Article
Window chambers are support structures implanted in the dorsal skin fold of a rodent model. Optical imaging of window chambers has been used in many basic cancer and vascular biology studies. We have recently shown that this technique can be extended to MRI by using plastic rather than metal window chambers. Here we describe a system for simultaneo...
Article
We have developed a mobile confocal microendoscope system that provides live cellular imaging during surgery to aid in diagnosing microscopic abnormalities including cancer. We present initial clinical trial results using the device to image ovaries in-vivo using fluorescein and ex-vivo results using acridine orange. The imaging catheter has improv...
Article
Full-text available
The confocal microendoscope is an instrument for imaging the surface of the human ovary. Images taken with this instrument from normal and diseased tissue show significant differences in cellular distribution. A real-time computer-aided system to facilitate the identification of ovarian cancer is introduced. The cellular-level structure present in...
Article
We have developed a mobile confocal microendoscope system that provides live cellular imaging during surgery to aid in diagnosing microscopic abnormalities including cancer. We present initial clinical trial results using the device to image ovaries in-vivo using fluorescein and ex-vivo results using acridine orange. The imaging catheter has improv...
Conference Paper
An ultrathin fiberscope that incorporates illumination and detection into a single channel is presented for broadband diffuse reflectance imaging. It consists of a 0.5 mm diameter imaging catheter (coherent fiber bundle cemented to a grin lens), illumination and collection optics, and a ccd camera. To obtain reasonable image contrast, surface scatt...
Article
Three-point Dixon techniques achieve good lipid-water separation by estimating the phase due to field inhomogeneities. Recently it was demonstrated that the combination of an iterative algorithm (iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL)) with a fast spin-echo (FSE) three-point Dixon method yi...
Article
Full-text available
A mobile confocal microendoscope for use in a clinical setting has been developed. This system employs an endoscope consisting of a custom designed objective lens with a fiber optic imaging bundle to collect in-vivo images of patients. Some highlights and features of this mobile system include frame rates of up to 30 frames per second, an automated...
Article
Full-text available
We present a modified multi-spectral configuration of a slit-scanning confocal microendoscope that provides higher spectral resolution in a fully automated interface. Tissue fluorescence signal is directed through a dispersive element that spreads the spectral information across the CCD camera mapping spectral information perpendicular to the confo...
Article
Full-text available
The acid-mediated tumor invasion hypothesis proposes altered glucose metabolism and increased glucose uptake, observed in the vast majority of clinical cancers by fluorodeoxyglucose-positron emission tomography, are critical for development of the invasive phenotype. In this model, increased acid production due to altered glucose metabolism serves...
Conference Paper
The confocal microendoscope is an instrument for optical biopsy that allows in situ imaging of tissue at the cellular level. Several promising clinical applications are emerging for this type of novel instrumentation.
Article
We present a laparoscope for fluorescence confocal microendoscopy specifically designed for microscopic imaging during diagnostic laparoscopic surgery. The catheter consists of a disposable rigid distal tip which houses a flexible microendoscope and dye channel. The laparoscopic tip is a small disposable polycarbonate sheath containing two inner lu...
Article
Full-text available
We previously reported on the development and testing of a multi-spectral confocal microendoscope. Here we present a new system that will be used during an early stage clinical trial. The new microendoscope is significantly smaller, uses fewer optical elements, and is structurally more robust. The slit-scanning confocal system employs two synchroni...
Article
In this work we present a new method for the improved detection of lipid infiltration in the heart. The method employs a double-inversion fast spin-echo technique where the acquisition of water- and lipid-suppressed k-space data is alternated between TR periods to produce co-registered lipid and water images from data acquired in a breath hold. The...
Article
An ultrathin fiberscope has been developed that incorporates broadband illumination and imaging within a single 0.5 mm coherent fiber bundle by allotting a portion of the numerical aperture to illumination.
Article
The fluorescence confocal microendoscope is an instrument that integrates a confocal microscope with a clinical endoscope. Several types of systems have been developed to achieve this capability enabling a number of promising clinical applications.
Article
Full-text article is not available.
Conference Paper
Fiber optic-imaging bundles have been evaluated to characterize their fluorescence properties. Excitation-emission maps were generated in the UV/visible range using a customized spectrometer.
Conference Paper
SNARF-1, a pH-sensitive fluorescent probe, was used to perform fluorescence ratio imaging in tumor and surrounding tissue. A pH resolution of 0.042 pH units was achieved. pH gradients extending into the peritumoral region were observed.
Conference Paper
The fluorescence confocal microendoscope (CM) is a new type of instrument for imaging the surface of the human ovary and has diagnostic implications for the early detection of ovarian cancer. The purpose of this study was to develop an automated system to facilitate the identification of ovarian cancer from digital images captured with the CM syste...
Article
Radially acquired fast spin-echo data can be processed to obtain T2-weighted images and a T2 map from a single k-space data set. The general approach is to use data at a specific TE (or narrow TE range) in the center of k-space and data at other TE values in the outer part of k-space. With this method high-resolution T2-weighted images and T2 maps...
Article
Radial fast spin-echo (radial-FSE) methods enable multishot diffusion-weighted MRI (DWMRI) to be carried out without significant artifacts due to motion and/or susceptibility and can be used to generate DWMRI images with high spatial resolution. In this work, a novel method that allows isotropic diffusion weighting to be obtained in a single radial...
Article
RAD-GRASE is an MRI sequence that combines radial (RAD) k-space scanning with the gradient and spin-echo (GRASE) technique. RAD-GRASE has the advantages of all radial data acquisition methods in that it can reduce motion sensitivity and correct motion-induced data errors, which can be exploited to achieve high-resolution diffusion-weighted imaging...
Article
Full-text available
The fluorescence confocal microendoscope provides high-resolution, in-vivo imaging of cellular pathology during optical biopsy. There are indications that the examination of human ovaries with this instrument has diagnostic implications for the early detection of ovarian cancer. The purpose of this study was to develop a computer-aided system to fa...
Article
Full-text available
A multi-spectral confocal microendoscope (MCME) for in-vivo imaging has been developed. The MCME employs a flexible fiber-optic catheter coupled to a slit-scan confocal microscope with an imaging spectrometer. The catheter consists of a fiber-optic imaging bundle linked to a miniature objective and focus assembly. The focus mechanism allows for ima...
Article
Epithelial ovarian cancer has the highest mortality rate among the gynecologic cancers and spreads beyond the ovary in 90% of the women diagnosed with ovarian cancer. Detection before the disease has spread beyond the ovary would significantly improve the survival from ovarian cancer, which is currently only 30% over 5 years, despite extensive effo...
Article
Sequences based on the distant dipolar field (DDF) have shown great promise for novel spectroscopy and imaging. Unless spatial variation in the longitudinal magnetization, Mz(s), is eliminated by relaxation, diffusion, or spoiling techniques by the end of a single repetition, unexpected results can be obtained due to spatial harmonics in the steady...