[Radioiodine therapy for combined disseminated and nodular thyroid autonomy. Results after using a correction term...

In combined focal and disseminated thyroid autonomy a variety of concepts in the treatment with radioiodine are used. The difference lies mainly in the calculation of the autonomous volume. This retrospective study shows a new method of calculating the autonomous volume.

In 398 patients with combined thyroid autonomy and good correlation of scintigraphically hot nodules and lesions defined by ultrasound the volume of the nodules is ascertained from scintigraphic and ultrasound parameters and the volume of the disseminated autonomous tissue is assessed with a weighting factor (VF). This factor is the ratio of impulse density in a ROI over the disseminated volume divided by the corresponding impulse density over the nodular volume of the thyroid scintigraphy. The sum of nodular volume and weighted perinodular volume gives the total autonomous volume. A standard radioiodine test gives the maximum iodine-131-uptake and effective half-life to calculate the activity to obtain a treatment dose of 400 Gy.

The rate of success with and without thyrostatic medication was 97% with an 18.6% rate of hypothyroidism observed from 4 months post therapy onwards.

The use of the weighting factor VF in the treatment of combined autonomy leads to an excellent rate of success in patients with good correlation of functional imaging and ultrasound findings.