[MRI and oncoscintigraphy with 99m-Tc-MIBI in the follow up of thyroid cancer].

Magnetic resonance imaging (MRI) and 99mTc-MIBI oncoscintigraphy are new procedures for the detection of recurrent differentiated thyroid cancer. We evaluated the utility of both techniques compared to ultrasonography, radioiodine scanning, and measurement of serum thyroglobulin in patients with (n = 21) or without suspicion (n = 34) of tumor relapse. Although MRI was most effective in detecting local recurrencies (sensitivity: 100%), additional diagnostic information was only obtained in patients with mediastinal lesions. On the other hand, oncoscintigraphy was less sensitive (67%) but highly specific in differentiating reactive lymph node enlargement from metastatic disease (specificity: 93.5%). Oncoscintigraphy may be used instead of radioiodine scanning in patients with doubtful lymph node findings and spare them withdrawal of TSH-suppressive hormone medication. Routine estimation of serum thyroglobulin proved to be highly efficient in screening for tumor relapse using a cut-off level of 3 ng/ml (accuracy: 100%).