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Figure 1.  Graves disease in a 24-year-old woman. Laboratory values were as follows: T4 = 16.7 µg/dL, T3 = 311 ng/dL, and TSH < 0.01 µIU/mL. The 24-hour RAIU was 84%. Anterior distant image obtained with Tc-99m pertechnetate shows an enlarged thyroid. The target-to-background activity is increased to such an extent that the submandibular salivary glands (arrowhead) are barely visualized. Note the appearance of the pyramidal lobe (large arrow). The round photopenic area (small arrow) in this and subsequent figures represents the 2-cm lead marker placed at the suprasternal notch.