Principles and features of ultrasound hypoechogenicity in diffuse thyroid pathology

For different thyroid diseases and hormonal metabolism, ultrasound (US) of the thyroid gland reveals hypoechogenicity. Despite the direct correlation of hypoechogenicity with the levels of thyroid-stimulating hormone and antibodies of thyroid peroxidase and thyroglobulin, ~20% of this correlation is inconsistent, thus restricting the comprehensive utilisation of this valuable diagnostic sign. Thus, it is necessary to investigate the additional circumstances affecting the extent and features of the US hypoechogenicity of the thyroid gland. The technique for assessing thyroid hypoechogenicity was based on the basic setting of the US mode and visual assessment in percentage of gray relative to a gradient gray scale. Doppler mode was used. US data were compared with the results of hormonal and immune blood tests. The study contains the morphofunctional basis of the various US hypoechogenicities detected in the diffuse pathology of the thyroid gland has been presented, and the principles and probable mechanisms of widespread and segmental hypoechogenicity formation are disclosed for the first time. Furthermore, a mandatory Doppler involving thyroid parenchyma blood flow intensity and peak systolic blood velocity of thyroid arteries, which indicates the magnitude of neurovegetative influence, has been suggested. The results of the study shows revealed that the evaluation of the importance and features of US hypoechogenicity in various diffuse thyroid pathologies is probably based on a single system involving neurohumoral regulation, segmental arrangement and compensatory reserve state of the gland parenchyma.