Background: With the advent of the use of serum thyroglobulin as a marker for the recurrence of well-differentiated thyroid cancer (WDTC) after total thyroidectomy, clinicians are increasingly faced with the diagnostic dilemma of detecting the site of recurrence in thyroglobulin-positive patients with normal clinical examinations. The high protein content of this thyroglobulin may make it specifically detectable by magnetic resonance (MR) imaging.
Objective: To determine the ability of MR imaging to detect the presence of metastatic WDTC in cervical lymph nodes.
Study design: Retrospective cohort.
Methods: Blinded review by two independent head and neck radiologists of 34 head and neck MR scans obtained from 26 patients with thyroid cancer (12 with primary disease and 14 with recurrent disease) all of whom subsequently underwent surgical removal of the lymph nodes considered at risk by imaging.
Results: The average overall percent sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of MR imaging were 95%, 51%, 84%, 78%, and 83%, respectively. The concordance between the two radiologists was 69%. There was no overall difference in the ability of the MR scan to detect the presence of disease in the upper jugular, lower jugular, or paratracheal nodal stations. However, it was more useful for papillary carcinoma (PPV 86%, accuracy 85%) than for follicular carcinoma or the follicular variant of papillary carcinoma (PPV 63%, accuracy 67%).
Conclusion: MR imaging is a sensitive and accurate technique for the detection of WDTC, particularly papillary carcinoma, metastatic to cervical lymph nodes. However, the lower specificity of this modality precludes its use as a screening tool.