Thyroid classification: Where have we been and where are we going?

Abstract

Ultrasound is the most common imaging technique for the assessment of the thyroid gland. Thyroid disease can be focal (nodule) or diffuse (multinodular thyroid, Grave's, Hashimoto's thyroiditis, subacute viral thyroiditis). While ultrasound provides excellent anatomical depiction of the thyroid gland, ultrasound is not a histological examination. Because virtually any nodule containing solid tissue represent a malignancy, numerous rules, guidelines and scoring systems have been used in an effort to stratify the risk based on a wide variety of anatomical features including: size, composition, shape, echogenicity, echotexture, margins, presence and nature of calcifications. Two different strategies have been used in the development of thyroid nodule classification systems. One strategy relies on pattern-recognition and the other relies on numerical scoring of each nodule. In this presentation, we will review and compare these strategies and discuss what they mean for the practitioner. Specific advice will be provided for non-clinician practitioners (sonographers) on how to improve the efficiency of the thyroid examination and avoid becoming paralysed by the high-level of cognitive detail in patients with multinodular thyroid glands.