ARRS 2022 Abstracts

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E2142. Imaging of Post-Operative Neck After Thyroidectomy: What to Look For, How to Diagnose, and How to Manage
Authors
  1. Anne Sailer; Yale University School of Medicine
  2. Nadia Solomon; Yale University School of Medicine
  3. Douglas Katz; NYU Winthrop University Hospital
  4. Margarita Revzin; Yale University School of Medicine
Background
Neck sonography plays a key role in the surveillance of post-thyroidectomy patients for the detection of locoregional papillary thyroid cancer recurrence in both low- and high-risk patients. It is important for those who interpret these examinations to be familiar with the typical findings of tumor recurrence in the post-operative neck as well as the potential pitfalls in sonographic technique that may result in the failure to detect or the misinterpretation of lesions.

Educational Goals / Teaching Points
The goals of this exhibit are to familiarize radiologists with anatomy of the main neck structures and lymph node chains; briefly discuss lymphatic drainage of primary and metastatic neck tumors; review the expected post-surgical changes in the neck and associated complications; discuss imaging characteristics of benign and malignant neck lymph nodes and its mimics; and provide an algorithm for definitive evaluation of suspicious lymph nodes and discuss universal treatment management and follow up.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
The exhibit includes the following key points. 1) Anatomy of the main neck structures, neck lymph node chains, and neck mapping (Level 1–7 lymph node chain); 2) Lymphatic drainage of the primary neck tumors, specifically thyroid cancer and common neck metastases; 3) role of imaging in evaluation of immediate post-operative neck and serial follow-up (CT, nuclear medicine, ultrasound [neck mapping protocol]) and their role in management of patients with resected thyroid cancer; 4) imaging appearance of benign neck lymph nodes (size, distribution, composition, vascularity); and 5) imaging characteristics of indeterminate and suspicious lymph nodes (calcifications, increased vascularity, cystic spaces, confluent and conglomerate chain lymph nodes; thyroid cancer lymph node metastases and others). The exhibit also includes pitfalls in diagnosis (neck fat necrosis, strap muscle calcifications, granulomas, residual [regenerated] thyroid gland; imaging of post-operative complications (abscess, vascular, laryngeal nerve, and tracheal injury); and a flow chart for algorithmic management of patients with normal neck mapping or suspected abnormalities (i.e., annual follow-up versus biopsy, radiation treatment, CT CAP, laboratory analysis).

Conclusion
Sonography is the most sensitive modality for detecting locally recurrent tumors and regional nodal metastasis and therefore is an integral component of post-thyroidectomy surveillance. However, a wide variety of benign findings may be visualized in the postoperative neck, potentially mimicking recurrent disease. Therefore, familiarity with the characteristic appearance of recurrent papillary thyroid carcinoma and the differential considerations are important to ensure appropriate treatment of post-thyroidectomy patients. Although the imaging appearance may be diagnostic, it is important to be aware that ultrasound-guided FNA may still be necessary in some cases, especially if the clinical suspicion is high based on rising Tg levels and the biological type of the patient's disease.