Iodine-123 SPECT of the thyroid in multinodular goiter.

Iodine-123 single photon emission computed tomography (SPECT) imaging of the thyroid was performed in two patients with multinodular goiter and swallowing difficulty to provide the functional and anatomic orientation of the goiter in relation to the airway. Transaxial slices showed the retrolaryngeal extension of the enlarged thyroid and the tracheal compression by the goiter in both patients. Sagittal and coronal sections confirmed the posterior extension of the goiter. Tracheal displacement was confirmed by roentgenography of the neck in both patients. Vocal cord paralysis demonstrated by fiberoptic laryngoscope and esophageal compression shown by esophagography were found in a patient with toxic multinodular goiter with coexisting papillary carcinoma of the thyroid. In this patient, both the tracheal compression noted in SPECT imaging and the tracheomalacia suggested by the flow volume loop pattern in pulmonary function test were confirmed at the time of thyroidectomy. Our observation suggests that SPECT imaging of large multinodular goiter may be useful in preoperative delineation of the functional anatomy and the extension of goiter in relation to the airway.