Do Negative ¹²⁴ I Pretherapy Positron Emission Tomography Scans in Patients with Elevated Serum Thyroglobulin Levels Predict Negative ¹³¹ I Posttherapy Scans?

Abstract

In our selected patient population, (131)I posttherapy scans are frequently positive in patients with elevated serum Tg levels, a negative diagnostic (131)I or (123)I scan, and a negative (124)I PET scan. Thus, for a patient with elevated serum Tg level, negative diagnostic (131)I planar scan, and a prior post-(131)I therapy scan that was positive, a negative (124)I PET scan will have a low predictive value for a negative post-(131)I therapy scan and should not be used to exclude the option of blind (131)I therapy.