The role of 99mTc-DTPA retrobulbar SPECT in staging and follow-up of Graves' orbitopathy.

The pathogenesis of Graves' orbitopathy (GO) is not completely understood. Coexistent hyperfunction of the thyroid gland is frequent; however, GO may also coexist with hypo- or euthyrodism. The course of GO is largely independent of thyroid function, although elevated serum TSH is known to negatively interfere with GO course. GO is severe in 10% of the cases; sight threatening complications may also develop. A successful therapy of GO requires the assesment of both the severity and activity of orbital inflammation. Based on relevant studies and our own experiences, the possible management choices are reviewed here. For this purpose, we compare the clinical value of imaging techniques for detecting the activity of the disease. During the last 15 years, we used 99mTc-DTPA retrobulbar SPECT routinely in more than 1400 patients to facilitate the right therapeutic decision. This diagnostic utility simplified management decisions compared to previously applied alternative techniques. We recommended the routine use of 99mTc-DTPA retrobulbar SPECT for the evaluation and follow-up of GO.