1,721,003 research outputs found
A new sonograpic method for the evaluation of skin permeability changes after irradiation with low frequency ultrasound.
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A new phantom for quality assurance of color-coded ultrasound equipment
No full textColor Doppler Ultrasound imaging is now routine in clinical use for evaluation of blood flow in vessels. Several phantoms and test objects are available on the market for Quality Assurance programs on color coded flow equipment but none of them allows the measurement of the spatial resolution of a color image system. A new phantom and measurement procedure for the assessment of the color spatial resolution is proposed. Various accessories can be inserted into an adapted plexiglas box, permitting the reproduction of two opposed parallel flows of synthetic blood. The box is then filled with a tissue mimicking solution. Measured flows were generated using a pump, a potentiometer and a flowmeter. It is possible to modify the liquid flow, the diameter of the simulated blood vessels, their inter-axial distance and their depth below the surface of the phantom. The apparatus measures the minimum inter-axial distance at which opposed flows can be color-resolved as a function of the flow velocity and the diameter of the vessels. Results concerning measurements on three commercial devices are presented and their different characteristics are reported
Comparison of strain and real time shear wave ultrasound elastography in the detection nad characterization of prostate cancer
No full textPhysics and technology of medical diagnostic ultrasound
No full textUse of ultrasound waves in the medical diagnostic procedures is discussed. Ultrasound diagnostics avails itself of the analysis of the reflected echoes from bodily tissues when irradiated with mechanical waves of appropriate frequency. Different physical parameters relative to an ultrasound wave, such as the amplitude, phase or frequency can be analyzed. Different possible analyses allow to obtain different information relative to the tissues being studied
A new method to assess the fluidodynamic behaviour of an angiographic contrast agent [Un nuovo metodo per la valutazione del comportamento fluidodinamico di un mezzo di contrasto angiografico]
No full textPurpose. To propose a new method for the assessment of the fluidodynamic behaviour of angiographic contrast agents. The method enables measurement of the spatial distribution and time dependence of the contrast agent along a pseudo-vessel on images obtained with an X-ray image intensifier. Material and methods. A particular phantom was devised consisting of a plexiglas box with an insert into which a latex tube with a 0.4 cm in diameter was placed in order to simulate the tortuous flow of a blood vessel. The box, which is filled with water to simulate the thickness of a normal patient, is connected to an injection and pumping system which serve to keep the contrast agent flowing in the pseudo-vessel tube. The pseudo-vessel tube was filled with plain water in one case and with saline solution in another case to assess their different dilution capabilities. The phantom and the flow of contrast agent were imaged with a conventional X-ray image intensifier system and the images were stored in digital format during 35 second acquisitions at a speed of 4 frames per second; for any frame it is possible to measure the mathematical contrast in any position in the image. Further, a diagram showing the time dependence of the spatial distribution of the mathematical contrast is proposed. The X axis shows the spatial distribution of the mathematical contrast, whereas the Y axis shows its temporal variation with a gray level proportional to the mathematical contrast value. By building an horizontal profile of this diagram one can obtain the spatial distribution at a fixed time, while by building a vertical profile one can obtain the temporal variation at a fixed point. Several different contrast agents were so tested. Results. The proposed method allows different fluidodynamic behaviour patterns of contrast agents and flowing media to be shown. Owing to the different chemical characteristics of water and saline solution these media have different dilution capabilities (higher for water) and this is well demonstrated by the diagram profiles obtained for each. The system has also allowed the detection of a particular behaviour of some contrast agents, whose spatial distribution was non uniform even in the last frames, thus showing a tendency to maintain their bolus-nature over time. An interesting feature which can be noticed in all the temporal profiles is the presence of a "prebolus", i.e. the contrast is higher at the very beginning of the flow, then decreases and after some time starts to increase again. Though the initial contrast value obviously depends on the iodine concentration employed, the method shows the contrast variation as a function of time is different for different contrast agents. Conclusions. The method and the equipment proposed provide a good description of the fluidodynamic behaviour of different contrast agents, but do not constitute a reference method for testing haemodynamic behaviour which, "in vivo", is obviously affected by several other chemical and metabolic factors. However, the method allows evaluation of the contrast agents from a physical and fluidodynamic point of view, showing that the iodine content is not the only feature affecting their behaviour. The method can be used in quality control to test the constancy of the physical behaviour of different contrast agents
Un nuovo metodo per la determinazione della risoluzione spaziale e di contrasto di sistemi color doppler.
No full textPhysical and clinical assessment of a method for the computer aided diagnosis in mammography.
No full textComparison of strain and real time shear wave ultrasound elastography in the detection and characterization of prostate cancer
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