Prinos analyzy textury ultrasonografickych obrazu v diagnostice difuznich procesu parenchymu stitne zlazy.

Ultrasonographic examination represents the basic imaging technique in diagnostics of thyroid diseases. It is a non-invasive procedure, that can be performed without preparation and the quality of the image does not depend on the body frame and co-operation of the patient. Focal changes are distinguishable already in their initial stages, and solid lesions can be easily differentiated from cystic formations; nevertheless, the biologic nature of a finding can not be reliably determined by ultrasonograms. But the situation in assessment of diffuse changes of the thyroid gland, particularly those that are caused by chronic autoimmune inflammations, is rather different. The characteristically low echogenity is not present in all cases with microscopically confirmed lymphocytic infiltration. A correlation has been shown between the needle biopsy results and the presence of antibodies, but ultrasonographic examination remains an important and usually well accessible diagnostic method. The lyphocytic infiltration and the subsequent destruction of the parenchyma result in a structural change of the tissue. These changes cause an alteration of the texture of ultrasonographic image. The texture can be assessed by a histogram of the gray-level, or by the middle or the most frequent intensity of the gray. But such first-order texture characteristics are sensitive on the setting of apparatus and fail in border cases, in which the sonographists eye is not able to recognize the typical changes. Thus, another possibility is the analysis of the second-order statistical texture properties that show relations between the pixels of the same characteristics. The number of texture characteristics could be very high, but practically we have to limit it so that the usefulness of the method would not be reduced by the timely demanding calculations. We have introduced a system of saving of chosen thyroid gland images during the standard examination by means of digitalizations of the video-output signal of the apparatus Toshiba ECCOCEEE. The recording of images does not extent the examination or otherwise stress the patient. In the marked region of interest relations between pixels are assessed with the characteristic gray-level intensity and location according to the translation rules. This is done by a mask that must only be placed in a way in no image pixel is used more than once in the data collection. That assessment is based on the second order characteristics, systematically constructed with the aim to distinguish most efficiently between a healthy and pathologically transformed structure. Information that are needed to diagnose a diffuse process of the thyroid gland may be obtained from ultrasonographic images by the analysis of the second order texture characteristics, even in a case that can not be reliably assessed by the traditional subjective evaluation.Summary in EnglishAvailable from STL, Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi