The Role of Pretherapy Quantitative Imaging and Dosimetry in Radioiodine Therapy for Advanced Thyroid Cancer

SEL-I-METRY imaging schedule consisting of 24-h whole-body and SPECT ¹²³I-NaI scans before selumetinib, 24-h whole-body and SPECT ¹²³I-NaI scans after selumetinib, up to 4 additional dosimetry SPECT/CT ¹²³I-NaI scans after selumetinib, and up to 4 dosimetry SPECT/CT scans after treatment with 5.5 GBq of ¹³¹I-NaI. rhTSH = recombinant human thyroid-stimulating hormone; WB = whole body.

Example of whole-body planar scans at 24 h after ¹²³I-NaI administration at baseline, before selumetinib was administered (A), and after 4 wk of treatment with selumetinib (B).

Relative change in predicted ¹³¹I-NaI uptake after treatment with selumetinib with respect to uptake before selumetinib administration. Relative increase in uptake is shown for 9 patients who progressed to RAI therapy. P = patient.

Uptake of ¹³¹I-NaI before and after treatment with selumetinib. Solid lines represent relative increase in uptake by factors of 1, 10, and 100, respectively, to illustrate relative effect of selumetinib in individual patients and lesions. P = patient.

Relative increase in ¹³¹I-NaI uptake after treatment, with selumetinib plotted against baseline uptake of ¹³¹I-NaI before treatment. P = patient.

Comparison of absorbed doses for each lesion as predicted from pretherapy dosimetry and measured from posttherapy dosimetry.