Diagnostic Approach for Suspected Multinodular Goiter

Initial Diagnostic Steps

The American College of Radiology recommends ultrasonography as the initial diagnostic study for suspected multinodular goiter, followed by thyroid function tests (thyroid profile), to confirm the diagnosis, characterize the goiter, and assess thyroid function 1, 2
Ultrasonography is the preferred initial imaging modality for suspected goiter, as it confirms the cervical mass originates from the thyroid, characterizes the size and morphology of the goiter, evaluates suspicious characteristics in nodules if the goiter is nodular, and provides high-resolution images to stratify the risk of malignancy using ACR TI-RADS criteria 1, 2, 3
Thyroid function tests, including TSH, free T4, and free T3, should be performed to evaluate the functional status of the thyroid, with TSH being the most sensitive initial test (98% sensitivity, 92% specificity) 4

The American College of Radiology suggests that CT scans are indicated when there are obstructive symptoms or suspicion of subternal extension, as CT is superior to ultrasonography for evaluating subternal extension and the retropharyngeal space, and better defines the degree of tracheal compression 1, 2, 5
Biopsy should not be performed as the initial diagnostic study, but rather after ultrasonography has characterized the nodules, using ACR TI-RADS criteria to select nodules for fine-needle aspiration biopsy (FNAB) 1, 3

The American College of Radiology recommends against performing a radionuclide scan as the initial study in euthyroid patients, as it does not help determine malignancy or the decision to biopsy, and has a low positive predictive value 1, 2
PET/CT with FDG has no role in the initial evaluation of goiter 1, 2
If respiratory symptoms are present, CT should be added to evaluate tracheal compression before considering surgery 1, 5