After initial excellent response, the risk for recurrence is 1% to 2% in low-risk patients, 2% to 4% in intermediate-risk patients, and 14% in high-risk patients [45-47]. In general, more imaging modalities are used to pursue recurrence in high-risk Thyroid Disease patients because distant metastases are more likely in these patients and negatively impacts on survival. Recurrence with a structural abnormality can be treated with neck dissection, repeat RAI therapy, external beam radiotherapy, and systemic therapy [16]. US Thyroid US of the neck is the first imaging investigation for suspected DTC recurrence and includes evaluation of the thyroid bed and cervical nodes. It can characterize palpable abnormalities in the neck and detect deeper neck masses that are not palpable [28]. CT Neck CT of the neck complements US of the neck for detection of additional metastases in the central compartment, in the mediastinum, and behind the trachea [29,33,48] or for assessment for invasive recurrent disease into the aerodigestive tract. CT should be performed with iodinated contrast in order to better assess for tumor vascular encasement and small nodal metastases with hyperenhancement and necrosis. Contrast is not contraindicated for DTC based on new studies on iodine retention [11,12] (see Special Imaging Considerations section above). Dual-phase CT imaging with and without IV contrast does not provide any additional information. CT Chest CT imaging of the chest should be considered in high-risk DTC patients with elevated serum thyroglobulin (>10 ng/mL) or rising thyroglobulin antibodies with negative imaging studies in the neck. CT chest is favored over MRI chest because it is able to detect small pulmonary metastases [16]. Contrast CT is not necessary for pulmonary metastases but adds to evaluation of metastatic nodes and the thyroid bed. MRI Neck MRI of the neck and mediastinum has the same role as CT.
Thyroid Disease. After initial excellent response, the risk for recurrence is 1% to 2% in low-risk patients, 2% to 4% in intermediate-risk patients, and 14% in high-risk patients [45-47]. In general, more imaging modalities are used to pursue recurrence in high-risk Thyroid Disease patients because distant metastases are more likely in these patients and negatively impacts on survival. Recurrence with a structural abnormality can be treated with neck dissection, repeat RAI therapy, external beam radiotherapy, and systemic therapy [16]. US Thyroid US of the neck is the first imaging investigation for suspected DTC recurrence and includes evaluation of the thyroid bed and cervical nodes. It can characterize palpable abnormalities in the neck and detect deeper neck masses that are not palpable [28]. CT Neck CT of the neck complements US of the neck for detection of additional metastases in the central compartment, in the mediastinum, and behind the trachea [29,33,48] or for assessment for invasive recurrent disease into the aerodigestive tract. CT should be performed with iodinated contrast in order to better assess for tumor vascular encasement and small nodal metastases with hyperenhancement and necrosis. Contrast is not contraindicated for DTC based on new studies on iodine retention [11,12] (see Special Imaging Considerations section above). Dual-phase CT imaging with and without IV contrast does not provide any additional information. CT Chest CT imaging of the chest should be considered in high-risk DTC patients with elevated serum thyroglobulin (>10 ng/mL) or rising thyroglobulin antibodies with negative imaging studies in the neck. CT chest is favored over MRI chest because it is able to detect small pulmonary metastases [16]. Contrast CT is not necessary for pulmonary metastases but adds to evaluation of metastatic nodes and the thyroid bed. MRI Neck MRI of the neck and mediastinum has the same role as CT.