Sanjay Kadandale Shetty MD, Presenter: Nothing to Disclose

Michael M Maher MD, Abstract Co-Author: Nothing to Disclose

Peter Florin Hahn MD, Abstract Co-Author: Nothing to Disclose

Elkan F. Halpern PhD, Abstract Co-Author: Nothing to Disclose

Suzanne L. Aquino MD, Abstract Co-Author: Nothing to Disclose

To evaluate the significance of incidental abnormalities of the thyroid gland on thoracic and neck CT through correlation with ultrasound and pathology.

We conducted a retrospective review of CT and subsequent ultrasound (US) studies of 230 patients (F:M 159:71, mean 64.5 years) with incidentally detected abnormalities of the thyroid on helical CT (2.5-5 mm slice; 69% with IV contrast); none of these patients was referred for CT because of suspected pathology of the thyroid and none had a history of thyroid nodule or surgery. All CT and US studies were reviewed directly to correlate lesion characteristics between modalities and with site of biopsy. 118 patients had pathologic correlation.

CT matched subsequent US findings (mean 97 day delay) in 122 cases (53.0%), correctly identified the dominant nodule but missed multinodularity in 69 (30.0%), underestimated the number of nodules in 24 (10.4%), overestimated the number of nodules in 5 (2.2%), and corresponded to normal thyroid in 10 cases (4.4%). Punctate calcifications on CT significantly correlated to presence of microcalcifications on US (p 91 patients who had single or dominant nodules on CT had pathologic correlation: 7 were malignant (papillary or follicular carcinoma and lymphoma), 17 showed malignant potential (microfollicular), and 67 were benign. Of 27 patients with pathologic correlation who had multinodular or enlarged thyroid glands without a dominant nodule on CT, 2 were malignant and 25 were benign. No appearance on CT significantly differentiated benign from malignant disease. Patients 35 years or younger with an abnormality of the thyroid on CT were significantly more likely to harbor malignancy (p<0.02). If one assumes that all non-biopsied lesions were benign, this represents at least a 3.9% chance of malignancy (95% CI: 1.8-7.3%) and 7.4% chance of malignant potential (95% CI: 4.4-11.6%).

We found 11.3% incidence of malignant (3.9%) or potentially malignant lesions (7.4%) among incidental thyroid abnormalities detected on CT. Although no CT appearance correlated with the presence of malignancy, patients 35 years or younger had significantly greater incidence of neoplasia.

Shetty, S, Maher, M, Hahn, P, Halpern, E, Aquino, S, Significance of Incidental Thyroid Lesions Detected on CT: Correlation with Ultrasound and Pathology.  Radiological Society of North America 2004 Scientific Assembly and Annual Meeting, November 28 - December 3, 2004 ,Chicago IL. http://archive.rsna.org/2004/4404389.html