E1478. Thyroid Tumors: What the Radiologist Needs to Know
Brigham and Women's Hospital
Massachusetts Eye and Ear Institute
Thyroid nodules are a common finding and often incidentally detected at CT, MRI, PET, or on a clinical exam. In fact, benign thyroid nodules occur in at least 50% of the population over 50 years of age. Ultrasound (US) is the most commonly used to evaluate the thyroid gland. Therefore, it is imperative to understand the normal and abnormal appearance of the thyroid gland as well as features to differentiate between benign and malignant nodules. Radiologists play an important role in interpretation of imaging studies to provide guidance on management of these lesions.
Educational Goals / Teaching Points
The goals of this educational exhibit include: (1) to review thyroid anatomy; (2) explore imaging findings of both primary thyroid malignancies (papillary, medullary, anaplastic, and Hurthle cell), uncommon malignant thyroid gland tumors (such as thyroid lymphoma both primary and secondary, sarcoma, paraganglioma, metastases to the thyroid gland), and benign lesions (follicular adenomas); (3) understand correlative findings on CT, MRI, and PET/CT; (4) assess mimic of thyroid lesions (such as abscess, hematoma, thyroid cartilage chondrosarcoma); and (5) illustrate examples of both nodal and distant metastases. As important it is to diagnose thyroid cancers, it is also important to assist surgeons with pre-surgical planning and to help in assessment for recurrent disease. This comprehensive review will be presented in a case-based format from cases obtained from two tertiary care referral centers.
Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Radiologists work in conjunction with oncologists, surgeons, and endocrinologists in the assessment and treatment of patients with thyroid cancer. To work effectively, radiologists must understand the thyroid anatomy and adjacent structures to assist in treatment planning. Therefore, it is important to be well versed in multi-modality imaging including US for primary evaluation as well as cross-sectional tools such as CT, MRI, and PET/CT, which enable assessment of extrathyroidal extension, typical and atypical vascular anatomy, and metastatic nodal disease. Although not all medical centers use the Thyroid Imaging Reporting and Data System (TI-RADS), the ACR TI-RADS information will be reviewed to educate the reader on its applicability to thyroid nodule assessment.
Whether a thyroid nodule is discovered on a clinical exam or as an incidental thyroid nodule (ITN), it is imperative that radiologists understand the key sonographic features to differentiate benign from malignant lesion. The thyroid gland must be part of the search pattern in cross-sectional imaging to identify ITN. It is also important that radiologists are knowledgeable to correlate findings between different imaging modalities including CT, MRI, and PET/CT both for diagnostic purposes and in the assessment of metastatic disease.