Although IVUS is continuously gaining in use in practice due to its multiple clinical advantages, the technical process of IVUS image generation is not known to doctors and researchers developing IVUS image analysis. This fact leads to a simplified use, analysis, and interpretation of IVUS images based only on the gray-level values of image pixels.
In this chapter we discuss a basic physical model to generate synthetic 2D IVUS images. The model has different utilities: Firstly, an expert can generate simulated IVUS images in order to observe different arterial structures of clinical interest and their gray-level distribution in real images. Secondly, researchers and doctors can use our model to learn and to compare the influence of different physical parameters in the IVUS image formation, such as the ultrasound frequency, the attenuation coefficient, the beam number influence, and the artifact generations. Thirdly, this model can generate a large database of synthetic data under different device and acquisition parameters to be used for validating the robustness of image processing techniques. The IVUS image generation model provides a basic methodology that allows us to observe the most important real image emulation aspects. This initial phase does not compare pixel to pixel values generation, showing the coincidence with the real image, but looks for a global comparison method based on gray-level difference distribution. The input model applies standard parameters that have been extracted from the literature. Hence this model is generic in the sense that the model allows simulation of different processes, parameters, and makes it possible to compare to real data and to justify the generated data from the technical point of view.
The model is based on the interaction of the ultrasound waves with a discrete scatterer distribution of the main arterial structures. The obtained results of the validation of our model illustrate a good approximation to the image formation process. The 2D IVUS images show a good correspondence between the arterial structures that generate the image structures and their gray-level values. The simulations of the regions and tissue transitions of interest lumen, lumen/intima, intima/media, media/adventitia and adventitia, have been achieved to a satisfactory degree. Interested readers are invited to check the generation model in http://www.cvc.uab.es/~misael.
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