What is the role of CT scanning, MRI and PET scanning in the diagnosis of thyroid nodule?

Updated: Jan 09, 2018
  • Author: Steven K Dankle, MD; Chief Editor: George T Griffing, MD  more...
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CT scanning or MRI is generally not cost-effective in the initial evaluation of solitary thyroid nodules. Such studies may be useful in the assessment of thyroid masses that are largely substernal. Also, in some cases CT scan–guided FNAB may be helpful. PET scanning with 18F-fluorodeoxyglucose is at present primarily an investigational tool, but it might have some role in thyroid imaging in the future, particularly in the evaluation of metastatic disease. [12, 13] However, a study by Deandreis et al found PET scanning to offer no additional diagnostic benefit in the evaluation of a thyroid nodule that has been found to have indeterminate cytopathology on FNAB. [14]

In the past, nuclear imaging studies of the thyroid, often combined with ultrasonography, were routinely performed in initial assessment of thyroid nodules. Because only 10% of solitary thyroid nodules are hot and because 90% of cold nodules are not malignant, nuclear imaging with or without ultrasonography typically offers a low yield of cancer diagnoses in surgical specimens when their results are used as the main guides for referral to a surgeon.

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