[Thyroid nodules and non-functional goiters. Diagnostic contribution of nuclear resonance imaging]

The finding of a "cold" thyroid nodular or goiter raises the problem of its potential malignancy, usually resulting in systematic surgery. Ultrasonography and computerized tomography provide accurate information concerning the size, structure and connections of these abnormalities, but they have very little to say about their histological nature. We evaluated the contribution of magnetic resonance imaging (MRI) to the histological diagnosis by attempting tissue characterization before surgery in 97 patients with nonfunctional thyroid nodule or goiter. Comparisons with the pathological study of operative specimens showed a very small percentage (1.05 percent) of false negative results in terms of malignancy, and this was due to reliable arguments for benignity which we were able to collect from MRI signal intensity and structural analysis. Without these criteria, a decisive answer would have been very difficult, as shown by the significant rate of false positive results (14.73 percent) and a specificity of only 81.8 percent if every lesion interpreted as doubtful is considered malignant. Attention is drawn to the difficulties encountered in characterizing lesion with intracystic vegetations and in distinguishing between thyroiditis and lymphoma. The possibility of obtaining frontal and sagittal sections increases the usefulness of MRI. The operator's experience is essential in interpreting the signals and deciding on the therapeutic approach.