To improve the visualization and 3D-reconstruction of some pathological formations of the brain, it is offered to use a new method of processing of MR images with suppression of signals from normal tissues. The special attention is offered to be given suppression of signals of fatty tissue, free water and partially bound water of mucous membranes. For such way realization, it is offered to lead two scans with simultaneous suppression of two normal components and to multiply the obtained images. Simultaneous suppression of signals from two normal tissues is realized with the help of pulse sequence twice using inversion-recovery effect. Delays in pulse sequence are selected in accordance with the times of longitudinal relaxation of fat, free water and partially bound water. In comparison with earlier described technique of simultaneous suppression of signals of water and fat, the new method is especially useful at research of pathological formations when the zone of defeat is placed in a zone of nose bosoms. Besides allocation of a zone of defeat, MIP reconstruction becomes simpler. The offered technique well proves at research of tumors and hemorrhages.
In this paper we present the overview of problems and difficulties,
which are common in passive millimeter-wave imaging or radiovision.
The central part of the article is dedicated to mathematical
resolution enhancement methods - superresolution. We consider
several algorithms and discuss benefits and drawbacks they have.
Performance of the algorithms is demonstrated using a set of test
images, both simulated and real-life. Such advanced questions as
subpixeling technique and artifact suppression using the wavelet
transform are also reflected in the paper. The illustrations are
included in order to demonstrate significant improvement of the
resolution along with artifact suppression achieved on real-life
observed images. Influence of side lobes of PSF on image quality is
In this paper we present the overview of problems and difficulties, which are common in passive radio vision. The central part of the article is dedicated to mathematical resolution enhancement methods - superresolution. We consider several algorithms and discuss benefits and drawbacks they have. Performance of the algorithms is compared using a set of test images - both simulated and real-life. The last ones are taken using 3-mm and 8-mm passive radio vision systems. Such advanced questions as subpixeling technique and artifact suppression using the wavelet transform are also reflected in the paper. The illustrations are included in order to demonstrate significant improvement of the resolution along with artifact suppression achieved on real-life observed images.
The thermal radiation of rough water surface in small-scale approximation is considered. The mathematical model of radiating ability of multiwave perturbation is based on the Kirchhoff law of radiation, Leontovich boundary conditions and small perturbations method. The experimental research of radiating properties of the
rough water surface mock-up is carried out. The critical phenomena were revealed as increase of a thermal radiation in the certain allocated spatial directions.
In this paper we consider some aspects of radiovision systems.At the beginning,we examine the coherent phenomena in multisensor systems, and what benefits have the systems based on this phenomena. Later we
discuss the applications of calculated antenna pattern for,multi-channel radiovision system and show,that it can be used in some tasks if experimental one is not available. In the last section we consider superresolution methods,which allow to enhance resolution of the radio-thermal images btained,and exceed the bounds of the Rayleigh limit.The results of several data processing series are provided.
For enhancement of visualization and 3D image reconstruction of intracranial pathological forms, it is suggested to use MR images obtained with simultaneous water and fat signal suppression. In this case one can more distinctly reveal pathological forms which are hidden ordinarily under powerful signals of fat tissue (orbits and hypodermic fat) and free water (brain ventricles). To realize simultaneous suppression of strong water and fat signals, we use modified sequence "inversion-recovery" supplemented by second inversion pulse. The signal/noise ratio degrades insignificantly in comparison with common "inversion-recovery" technique. Yet due to suppression of intensive background signals the dynamic range of the receiver extends and its responsiveness to weak signals improves. Herewith the graphical data processing and construction of 3D images are significantly simplified as tissue contrast picture is maximally refined. The method is illustrated by 3D images in the cases of subdural haematomas and intracranial tumors. Drawing of 3D images for pathological forms was carried out by the standard software of MR scanner TOMIKON S50 (Bruker) which was used in MRI investigations.
This paper describes passive radiovision systems in 8-mm and 3-mm ranges. It contains short description of the systems, data processing algorithms and points out problems specific to multi-ray systems. Image enhancement methods are briefly considered. Several examples of radio thermal images of natural objects are presented herein.
MR diagnostics with obtaining images cleaned of strong signals of water and fat for discovery small tissue contrast variations related with a pathology is discussed. With help of water suppression, one can reveal the pathological changes of brain in small zones near the liquor spaces, particularly disseminated sclerosis cortical plaques, cerebral lesions, subarachnoid hemorrhage. Under the fat suppression T2-weighted images, inflammatory changes in orbits, cranial base, and spine are surely determined. Among several methods of water or fat suppression, one can indicate methods based on frequency selective saturation of fat signals and methods based on inversion-recovery (IR) pulse sequence. Simultaneous suppression of fat and water opens up additional possibilities in medical diagnostics. We realized simultaneous suppression of fat and water signals at the MR scanner Tomikon S50 (Bruker). We used a pulse sequence based on the IR technique, supplemented with special procedure of frequency-selective fat saturation. Sometimes only simultaneous suppression of fat and water signal made possible successful MRI diagnostics.
Proc. SPIE. 4029, Targets and Backgrounds VI: Characterization, Visualization, and the Detection Process
KEYWORDS: Point spread functions, Super resolution, Radio optics, Imaging systems, Distortion, Digital imaging, Antennas, Modulation transfer functions, Multichannel imaging systems, Resolution enhancement technologies
The designers of modern devices of vision prefer to choose a scanning step of receiving system antenna with some less size than the main lobe of Point Spread Function (PSF). They tell such systems are good constructed. However there is a problem of additional increase of resolution for such well constructed receiving system. This problem is naturally connected with improvement of mathematical models. The report is devoted to development and applications of local-linear method of additional enhancement of resolution for such receiving system in radio vision and optics.
Radio vision systems on the basis of radio optical devices combined with sensor measurements were created. Mathematical modeling of the super-resolution regimes for the systems were carried out for different receiving schemes and varied levels of applied distortion. The main purpose of this report is the comparison of resolution from an 8-mm wave and 3-mm wave radiometric range system.
Methods of mathematical modeling of multiple ray radio vision systems of image formation with antenna pattern distortion compensation in millimeter wavelength range were developed and improved at the Faculty of Physics of the Moscow State University. At present, intensive experimental investigations of multiple-ray radio vision systems on the basis of radio-optical devices with the sensor measurements are being carried out. The main purpose of the report is demonstration of the local-linear method capability of super-resolution on the model pictures with a small signal/noise ratio.
The designers of modern devices of vision prefer a scanning step of receiving system antenna with a smaller size aperture than the main lobe pattern of the Point Spread Function. This report is devoted to the development and application of a local-linear method of additional resolution enhancement for such a receiving system in radio vision and optics.
Methods of mathematical modeling of multiple rays radiovision systems of image formation with antenna pattern distortion compensation in millimeter wavelength range are developed and improved at the Faculty of Physics of Moscow State University. At the moment intensive experimental investigations of the working multiple rays radiovision systems on the base of phased antenna array and radio- optical systems with the rules and sensors frames are carried out. In the report the possibilities of developed dialog program complex for multiple rays systems of image registration and formation with following antenna pattern distortions compensation are shown on the base of the real data.
Wide usage of new approaches in radiovision for the sake of radio astronomical investigation is expected as they can fix image independently of the atmosphere state. New ranges of radiation registration promise to show new processes and phenomena in astronomy. Existing Sun radiovision system doesn't give possibility to resolve the details of the processes on the Sun fine structure. Near zone of the radiotelescope is so big that it doesn't allow to measure Sun radiovision system Point Spread Function (PSF) by the ground based methods. By the other words, it's impossible to estimate minimal point object (PSF) that could be seen on the Sun by ground based methods. The task of radiovision system PSF estimation was solved valuing the Sun's edge in the assumption of PSF circular symmetry. In the paper the possibilities of developed dialog complex of complicated Sun's radio observing system modeling with subsequent antenna pattern distortions compensation by linear and nonlinear methods.
At the Faculty of Physics of Moscow State University experimental researches of the working radiovision systems on the base of phased antenna array and radio optical systems with the sensors rules are carried out. Since 1980 the system of Sun radio observation in 3-mm wavelength range created by the specialists of Bauman Moscow State Technical University is exploited. Investigations in the mathematical modeling of image formation systems in wide wavelength range with different receiving schemes and with distortion compensation task solution and super-resolution are conducted by mathematician and physicists.
Proc. SPIE. 3378, Passive Millimeter-Wave Imaging Technology II
KEYWORDS: Mathematical modeling, Point spread functions, Extremely high frequency, Data modeling, Fourier transforms, Distortion, Antennas, Modulation transfer functions, Systems modeling, Instrument modeling
Method of optimization is considered to improve resolution and noise properties of millimeter-wave radio vision system. Conditions of optimal measurements are realized by coincidence of bandwidths both of signals and device.
Multielement radiometric matrix of sensors of millimeter-wave range was developed for radio-imaging in the range. Use of the matrix allows to transfer from mechanical scanning of observed scenes to electronic one and significantly decrease time of observation.
A method of passive millimeter-wave imaging with super- resolution using a phased array antenna system has been developed. The enhancement of the image resolution has been achieved by using several mathematical methods including the new method of reduction invented by the Russian mathematician Pytiev.
Creation of millimeter wave range radiovision system with super-Rayleigh resolution is considered. On the base of phased antenna array (PAA) radiometer, methods of observed scenes scanning (survey) and output signals processing are developed to provide a vision with resolution on the order higher than Rayleigh level. Optimum mathematical methods (of type of reduction, deconvolution, decomposition) for processing of output signals of scanning radiometer are developed. Effective mathematical model of control by PAA pattern is built. Interconnection between sensitivity and resolution of radiometer measure-computer system with PAA is investigated, including the case of high level of noises. Algorithms of revealing of scenes elements with super-resolution are developed. As a result, created in 8-mm range measure-computer system with antenna array for environmental investigations provides 10- fold increasing of resolution of radiometer over Rayleigh level.
A new active radiosounding method is suggested for global satellite monitoring of a Earth's ozone layer. The method is based on millimeter wave transmission along the path between two satellites, one carrying a transmitter, the other one carrying a receiver. In the case of paths passing over 10 km above the Earth's surface, the influence of oxygen and water vapor absorption is absent, therefore signals of ozone absorption for 2 to 3 mm wavelength spectral lines are free from any interference. In comparison with well-known radiometry, the method is distinguished by its particular precision and resolution.
Effective radiometric models in IR and millimeter waves ranges were developed for remote measurements of a sea surface in the real time. Real time processing of IR-radiometer signals was accelerated by decreasing of integration intervals in the space of angles of sight. A 3D model was developed in the millimeter wave range for a 2-scale rough sea surface. The suggested models yield the wind velocity (IR-model), wave spectrum and direction of the sea surface waves (millimeter-range model).