Laboratory Studies
All patients require thyroid function studies to assess for hyperthyroidism.
Consider a preoperative serum calcium study.
Imaging Studies
CT scanning or MRI
CT scanning and MRI generally are the most useful and important diagnostic and preoperative imaging studies because they allow for a fairly detailed assessment of the relevant anatomy, including surrounding tissue planes. CT scanning with iodinated contrast media should generally be avoided to preclude triggering of thyrotoxicity. However, if CT scanning with contrast is performed, it should follow thyroid scanning because nuclear imaging is not possible for several weeks after this iodine load.
Chest radiography
These images often are quite useful because they can reveal the presence of tracheal deviation or compression.
Chest radiography sometimes provides the first evidence of a mediastinal mass.
Barium esophagraphy
Barium esophagraphy is often obtained in the evaluation of dysphagia because it may demonstrate extrinsic compression or deviation. Barium esophagraphy is often not particularly helpful in the preoperative assessment of known substernal goiter.
Nuclear thyroid imaging and sonography
Nuclear thyroid imaging may demonstrate thyroid activity in the mediastinum, but the absence of uptake in the mediastinum does not exclude a diagnosis of substernal goiter.
Sonography may demonstrate the presence of a mediastinal mass, but it is not as helpful as chest radiography or CT scanning.
Neither nuclear imaging nor sonography is necessary in the preoperative assessment of known substernal goiter.
Diagnostic Procedures
Fine-needle aspiration of goiters for cytologic analysis may be helpful when a significant cervical component exists; however, they often are not recommended for substernal goiters because they may be dangerous or impossible to obtain. [4]
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Patient with a goiter. Prominent side-view outline.
