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Houston, TX, United States

Akhtar M.W.,University of Houston | Kleis S.J.,University of Houston | Metcalfe R.W.,University of Houston | Naghavi M.,Fairway Medical Technologies Inc.
Journal of Biomechanical Engineering | Year: 2010

Both structural and functional evaluations of the endothelium exist in order to diagnose cardiovascular disease (CVD) in its asymptomatic stages. Vascular reactivity, a functional evaluation of the endothelium in response to factors such as occlusion, cold, and stress, in addition to plasma markers, is the most widely accepted test and has been found to be a better predictor of the health of the endothelium than structural assessment tools such as coronary calcium scores or carotid intima-media thickness. Among the vascular reactivity assessment techniques available, digital thermal monitoring (DTM) is a noninvasive technique that measures the recovery of fingertip temperature after 2-5 min of brachial occlusion. On release of occlusion, the finger temperature responds to the amount of blood flow rate overshoot referred to as reactive hyperemia (RH), which has been shown to correlate with vascular health. Recent clinical trials have confirmed the potential importance of DTM as an early stage predictor of CVD. Numerical simulations of a finger were carried out to establish the relationship between DTM and RH. The model finger consisted of essential components including bone, tissue, major blood vessels (macrovasculature), skin, and microvasculature. The macrovasculature was represented by a pair of arteries and veins, while the microvasculature was represented by a porous medium. The time-dependent Navier-Stokes and energy equations were numerically solved to describe the temperature distribution in and around the finger. The blood flow waveform postocclusion, an input to the numerical model, was modeled as an instantaneous overshoot in flow rate (RH) followed by an exponential decay back to baseline flow rate. Simulation results were similar to clinically measured fingertip temperature profiles in terms of basic shape, temperature variations, and time delays at time scales associated with both heat conduction and blood perfusion. The DTM parameters currently in clinical use were evaluated and their sensitivity to RH was established. Among the parameters presented, temperature rebound (TR) was shown to have the best correlation with the level of RH with good sensitivity for the range of flow rates studied. It was shown that both TR and the equilibrium start temperature (representing the baseline flow rate) are necessary to identify the amount of RH and, thus, to establish criteria for predicting the state of specific patient's cardiovascular health. Copyright © 2010 by ASME. Source


Grant
Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 143.69K | Year: 2005

DESCRIPTION (provided by applicant): The main objective of this project is to develop a contrast agent to allow noninvasive imaging and monitoring of breast cancer with molecular specificity. The basis of the proposed method is a combination of optoacoustic imaging, nanotechnology and molecular biology of cancer. Laser Optoacoustic Imaging System (LOIS) uses near-infrared laser pulses to generate acoustic sources in tumors and the time-resolved detection of resulting transient ultrasonic waves. Clinical studies on breast cancer patients demonstrated that the combination of pulsed laser excitation (which provides high optical contrast between normal and malignant tissue) with the time-resolved detection of ultrasonic waves (which provides undistorted tomographic information from significant depths of tissue), yields a breast imaging system with capability to detect small tumors in situ. On the other hand, one can predict that some breast tumors may possess materially reduced optoacoustic contrast relative to that currently observed in patients with advanced cancer. These cases include: (1) early cancer stages (tumors with dimensions of 1-3 mm) that do not possess dense microvascular network, and (2) tumors treated with anti-angiogenesis chemotherapy. Therefore, we propose to develop and test a Nanoparticulate Optoacoustic Contrast Agent (NOCA) based on gold nanorods (NR) conjugated to antibodies against breast cancer receptors. Recently we demonstrated that gold nanorods represent a unique optoacoustic contrast agent. The optical absorption in gold nanorods is over 10(8)1/cm, i.e. >1000 times stronger than that of any organic molecules. Average near-IR absorption of cancerous tissue loaded with nanorods in concentration of only 10 nanorods per cell will provide additional noticeable contrast of delta-mu about 0.5 cm(-1) relative to normal tissue. Furthermore, the laser-induced acoustic signal from gold nanorods was found an order of magnitude stronger than an optoacoustic signal from dye-solution with equal absorbance. We propose to develop NOCA to utilize the full diagnostic power of LOIS, expanding its imaging capabilities to early carcinoma in situ and other breast tumors with underdeveloped microvasculature. The Phase-I project should result in the proof of feasibility in animals with simultaneous demonstration of our capability to control bioeffects of laser - nanorod interactions.


Grant
Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 1.22M | Year: 2008

DESCRIPTION (provided by applicant): The objective of this project is to develop a new advanced imaging system to allow visualization of small cancerous tumors in situ based on combination of two types of tissue contrast: (1) molecular contrast of deoxygenated hemoglobin associated with the function of aggressive malignancy to develop angiogenesis and consume oxygen and (2) structural contrast based on increased density of tumors relative to normal tissue. The functional contrast will be provided by the Laser Optoacoustic Imaging System (LOIS) and the structural contrast will be provided by ultrasound imaging. In the course of the two previous projects sponsored by NCI (R33CA095883, R44CA089959) we developed a clinical prototype of two-dimensional LOIS and performed feasibility testing in 36 breast cancer patients. The clinical results enabled the receipt of over $3 million in private funding for development of the commercial clinical system. On the other hand, our clinical studies showed that 3D optoacoustic imaging and correlation of LOIS with ultrasound, current FDA-approved adjuvant to X-ray mammography, will permit realization of the full diagnostic potential of the optoacoustic imaging and expedite radiologist's acceptance of LOIS as a clinical diagnostic imaging modality for breast cancer. Therefore, we propose a fast-track SBIR project to resolve technical issues associated with ultrawide-band ultrasonic transducers made of a novel piezoelectric ceramics (lead metaniobate), novel hardware, firmware and software that combines LOIS and USI systems, and finally, pilot clinical testing of the new system. The proposed 3D system will display 2D images of breast slices in real time and display the final 3D image upon execution of the translation scan along the axis along the laser beam and orthogonal to the slices. The operator will have an option of imaging in the optoacoustic mode, the ultrasound B mode or the combined mode correlating two types of tissue contrast, anatomical and functional. The present methods of medical imaging are only marginally successful in differentiating between cancerous and normal breast tumors. Optoacoustic imaging utilizes the highest known physical or chemical contrast of cancerous tissues relative to normal or benign tissue based on absorption of blood in the tumor microvessels and provides images with excellent resolution of 0.5 mm typical of ultrawide-band ultrasonic imaging. Novel PET/CT and 3D CT and MRI systems being developed do not provide real-time images and will have multimillion dollar price tags. We will utilize electronic hardware and software developed in the course of previous and ongoing R&D projects for development of a more advanced system for breast cancer. The focus of the Phase-I project will be on development, fabrication and testing of a single transducer elements capable of ultrawide-band ultrasound detection and emission of ultrasound pulses with no ringing. The Phase- II project will develop an arc-shaped linear array of novel transducers and its mechanical translation that simulates 2D array, modify firmware and software of the present system to enable dual modality operation and correlation of the two types of images, and test the system in phantoms followed by clinical evaluation in 12 patients with breast cancer. Successful accomplishment of the proposed project will motivate our investors to engage in the commercial development and the process of FDA approval.


Grant
Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase I | Award Amount: 0.00 | Year: 2003

DESCRIPTION (provided by applicant):Experimental work done to date indicates that Optoacoustic Tomography will provide breast images with greater contrast and sensitivity to cancer than the currently preferred methods. In a Laser Optoacoustic Imaging System (LOIS), short, near-infrared laser pulses are preferentially absorbed by breast tumors. As a result, pressure waves are generated at the absorption sites. These propagate to the surface where they can be detected with ultra-wideband ultrasonic transducers. Computer processing of the detected signals results in an image in which contrast is largely determined by the tissue blood content. Cancerous tumors are blood rich because they develop a dense network of leaky blood vessels through the process of angiogenesis. The contrast in an optoacoustic image is significantly higher than that in images acquired with x-rays or ultrasound. Imaging with 2 different laser wavelengths can provide diagnostic information. Images taken with a wavelength of 1064 nm are particularly sensitive to the distribution of oxygenated blood. Images taken with a wavelength of 760 nm are more sensitive to the distribution of deoxygenated blood. Combining and/or comparing the two types of images yields a means for differentiation between cancerous and non-cancerous lesion. LOIS is suitable for examination of the breasts of all women, regardless of their age or skin color. The overall goal of this project is to develop a commercial prototype optoacoustic imager. The work of the Lasersonix team during Phase II will focus on incorporation of the components developed in Phase I into a complete 2D imaging system called LOIS-2D. LOIS-2D will be tested with 24 patients with suspicious breast lesions to verify the proper performance of the equipment and to perform initial tests of its diagnostic capability in collaboration with UTMB. The commercial prototype of a 3D optoacoustic imager, LOIS-3D, will be designed, developed, and fabricated. Specifically, a three-dimensional transducer array will be produced. The electronics and software will be modified to handle an increased number of detectors. The number of electronic channels that can be processed in parallel will be increased to 128. Image reconstruction will be performed in hardware. 3D images will be reconstructed in close to real time through a computer fusion of 20 images produced in real time.


Grant
Agency: Department of Health and Human Services | Branch: | Program: SBIR | Phase: Phase II | Award Amount: 830.33K | Year: 2003

DESCRIPTION (provided by applicant):Experimental work done to date indicates that Optoacoustic Tomography will provide breast images with greater contrast and sensitivity to cancer than the currently preferred methods. In a Laser Optoacoustic Imaging System (LOIS), short, near-infrared laser pulses are preferentially absorbed by breast tumors. As a result, pressure waves are generated at the absorption sites. These propagate to the surface where they can be detected with ultra-wideband ultrasonic transducers. Computer processing of the detected signals results in an image in which contrast is largely determined by the tissue blood content. Cancerous tumors are blood rich because they develop a dense network of leaky blood vessels through the process of angiogenesis. The contrast in an optoacoustic image is significantly higher than that in images acquired with x-rays or ultrasound. Imaging with 2 different laser wavelengths can provide diagnostic information. Images taken with a wavelength of 1064 nm are particularly sensitive to the distribution of oxygenated blood. Images taken with a wavelength of 760 nm are more sensitive to the distribution of deoxygenated blood. Combining and/or comparing the two types of images yields a means for differentiation between cancerous and non-cancerous lesion. LOIS is suitable for examination of the breasts of all women, regardless of their age or skin color. The overall goal of this project is to develop a commercial prototype optoacoustic imager. The work of the Lasersonix team during Phase II will focus on incorporation of the components developed in Phase I into a complete 2D imaging system called LOIS-2D. LOIS-2D will be tested with 24 patients with suspicious breast lesions to verify the proper performance of the equipment and to perform initial tests of its diagnostic capability in collaboration with UTMB. The commercial prototype of a 3D optoacoustic imager, LOIS-3D, will be designed, developed, and fabricated. Specifically, a three-dimensional transducer array will be produced. The electronics and software will be modified to handle an increased number of detectors. The number of electronic channels that can be processed in parallel will be increased to 128. Image reconstruction will be performed in hardware. 3D images will be reconstructed in close to real time through a computer fusion of 20 images produced in real time.

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