FOLLOW-UP OF THYROID-CANCER BY MRI AND TC -99M-MIBI ONCOSCINTIGRAPHY

Magnetic resonance imaging (MRI) and Tc-99m-MIBI oncoscintigraphy are new procedures for the detection of recurrent differentiated thyroid c ancer. We evaluated the utility of both techniques compared to ultraso nography, radioiodine scanning, and measurement of serum thyroglobulin in patients with (n = 21) or without suspicion (n = 34) of tumor rela pse. Although MRI was most effective in detecting local recurrencies ( sensitivity: 100%), additional diagnostic information was only obtaine d in patients with mediastinal lesions. On the other hand, oncoscintig raphy 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 i n patients with doubtful lymph node findings and spare them withdrawal of TSH-suppressive hormone medication. Routine estimation of serum th yroglobulin proved to be highly efficient in screening for tumor relap se using a cut-off level of 3 ng/ml (accuracy: 100%).