FIGURE 4. Planar images obtained 5 h (A) and 24 h (B) after ¹²³I administration and 7 d after ¹³¹I therapy (C) in patient with known pulmonary metastases 1 y after initial thyroid remnant ablation. Foci of uptake in lungs are faint on 5-h image but are clearly defined on 24-h image and are further confirmed by scan obtained 7 d after ¹³¹I therapy.