Técnicas diagnósticas de Medicina Nuclear en patología tiroidea: relación con los grupos TIRADS y citología Bethesda

Abstract

Introduction and objectives: Since its beginning, nuclear medicine has played an important role in the study and treatment of thyroid pathology. The finding of a thyroid nodule is a very frequent situation in daily clinical practice. Today, the development of new techniques including high-resolution ultrasound and fine-needle aspiration puncture has led to an important progress in diagnosis and management of the disease. These procedures have enable the development of classification systems that allow to categorise the nodules by its ultrasound characteristics (TI-RADS) and its cytological characteristics (Bethesda), providing guidance on the attitude to follow in each case. The aim of this work is to conduct a review of the guidelines and recommendations for thyroid scintigraphy as well as to establish its relationship with the TI-RADS groups and the Bethesda cytology. Synthesis: Because iodine plays an important role in the physiology and pathophysiology of the thyroid gland, iodine radiopharmaceuticals or its analogues are very suitable for the study of thyroid imaging. Despite the development of new and very precise techniques for the study of the thyroid nodule, thyroid scintigraphy remains the only technique capable of correlating thyroid anatomy and thyroid function and, therefore, it is the only test capable of demonstrating the presence of autonomous thyroid nodules, which rarely result in malignancy. Furthermore, images with specific tracers such as sestamibi-99mTc and 18F-fluorodeoxyglucose can provide information on the biological behavior of cytologically indeterminate nodules. Conclusion: Thyroid scintigraphy is the only diagnostic method that provides information on the functional state of the gland. Its integration into the TIRADS and Bethesda groups is of the utmost importance to avoid unnecessary biopsies. In addition, the use of specific radiopharmaceuticals, including positron emission tomography, provides useful information in the case of nodules cytologically indeterminate.