Table 9. Recommendation Matrix of Existing Guidelines (Clinical Situation 4: Suspected Recurrence of DTC).

Source Guidelines	AGREE II	Recommendation	Grading of Recommendation
2015 American Thyroid Association Management Guidelines for Adult Patients with Thyroid Nodules and Differentiated Thyroid Cancer	72	Following surgery, cervical US to evaluate the thyroid bed and central and lateral cervical nodal compartments should be performed at 6–12 months and then periodically, depending on the patient's risk for recurrent disease and Tg status	Strong recommendation, moderate-quality evidence
		If a positive result on US would change management, ultrasonographically suspicious lymph nodes > 8–10 mm in the smallest diameter should be biopsied for cytology with Tg measurement in the needle washout fluid	Strong recommendation, low-quality evidence
		Cross-sectional imaging of the neck and upper chest (CT, MRI) with IV contrast should be considered 1) in the setting of bulky and widely distributed recurrent nodal disease where US may not completely delineate disease; 2) in the assessment of possible invasive recurrent disease where potential aerodigestive tract invasion requires complete assessment; or 3) when neck US is felt to be inadequately visualizing possible neck nodal disease (high Tg, negative neck US)	Strong recommendation, moderate-quality evidence
		CT imaging of the chest without IV contrast (imaging pulmonary parenchyma) or with IV contrast (to include the mediastinum) should be considered in high risk DTC patients with elevated serum Tg (generally > 10 ng/mL) or rising Tg antibodies with or without negative RAI imaging	Strong recommendation, moderate-quality evidence
		Imaging of other organs including MRI brain, MR skeletal survey, and/or CT or MRI of the abdomen should be considered in high-risk DTC patients with elevated serum Tg (generally > 10 ng/mL) and negative neck and chest imaging who have symptoms referable to those organs or who are being prepared for TSH-stimulated RAI therapy (withdrawal or rhTSH) and may be at risk for complications of tumor swelling	Strong recommendation, low-quality evidence
British Thyroid Association Guidelines for the Management of Thyroid Cancer	84	Neck US should assess the thyroid bed for residual thyroid tissue as well as assessing the cervical lymph nodes for signs of metastatic disease. US-guided FNAC should be carried out when metastatic disease is suspected	4, D
ACR Appropriateness Criteria® Thyroid Disease	69	US of the thyroid; usually appropriate	Limited
		Neck CT without IV contrast; may be appropriate	Strong
		Neck CT with IV contrast; usually appropriate
		Neck CT with or without IV contrast; usually not appropriate
		Neck MRI without IV contrast; may be appropriate	Expert consensus
		Neck MRI with or without IV contrast; usually appropriate
		Chest CT without IV contrast; may be appropriate	Limited
		Chest CT with IV contrast; may be appropriate
		Chest CT with or without IV contrast; usually not appropriate
Revised Korean Thyroid Association Management Guidelines for Patients with Thyroid Nodules and Thyroid Cancer	33	Cervical US to evaluate the thyroid bed and central and lateral cervical nodal compartments should be performed at 6–12 months following surgery, and then periodically, depending on the patient's risk for recurrent disease and Tg status	Not available
		CT, MRI of the neck and upper chest with IV contrast should be considered 1) in the setting of bulky and widely distributed recurrent nodal disease where US may not completely delineate disease; 2) in the assessment of possible invasive recurrent disease where potential aerodigestive tract invasion requires complete assessment; or 3) when neck US is felt to be inadequately visualizing possible neck nodal disease (high Tg, negative neck US)	Not available
		CT of the chest without IV contrast (imaging pulmonary parenchyma) or with IV contrast (to include the mediastinum) should be considered in high risk DTC patients with elevated serum Tg (generally > 10 ng/mL) or rising Tg antibodies with or without negative RAI imaging
NCCN Clinical Practice Guidelines in Oncology, Thyroid Carcinoma, Version 1. 2019	75	Periodic neck US or other imaging (e.g., CT or MRI with contrast, chest X-ray, PET/CT) as clinically appropriate, may be considered in cases of clinical suggestion of recurrent disease	2A

ACR = American College of Radiology, CT = computed tomography, DTC = differentiated thyroid carcinoma, IV = intravenous, MRI = magnetic resonance imaging, NCCN = National Comprehensive Cancer Network, PET = positron emission tomography, RAI = radioactive Iodine, rhTSH = recombinant human thyrotropin, Tg = thyroglobulin, TSH = Thyroid stimulating Hormone, US = ultrasonography