[Clinical application of orbital scintigraphy with 99Tc(m)-octreotide in patients with thyroid associated ophthalmopathy]

To analyze the feasibility of estimation of thyroid associated ophthalmopathy (TAO) activity with orbital scintigraphy using 99Tcm-octreotide.

There were 30 cases of TAO and 11 volunteers without eye disease or thyroid disease (control group, CG). Some examinations were performed before treatment. Based on the clinical activity score (CAS) , all TAO patients were divided into 2 groups, active group (AG) and inactive group (IAG). Orbit scintigraphy study of orbit was completed within 1. 0 - 1. 5 h after intravenous injection of 740 MBq 99Tcm-octreotide. The best transverse slice for displaying eye was selected to take semi quantitative analysis. The regions of interest of right orbit (R) , left orbit (L) and occipital (0) were selected. The uptake ratios (UR) were calculated in (R + L)/20. And then, all active patients accepted immunosuppressive therapy with prednisone after 131I therapy. Six patients performed octreotide scan twice. The statistical analyses included ANOVA, Spearman regression analysis and paired t-test using SPSS 10. 0.

99Tcm-octreotide biokinetics showed a rapid blood clearance through urinary system. The orbit appeared as a "cold area" in CG. The orbit uptake of AG had a visual orbital accumulation of 99Tcm-octreotide, but little in IAG ( URact = 1.40 +/-0. 18, URinact = 1. 15+/-0. 10, URcontr= 1. 07 +/-0. 20). There was a significant difference between IAG and AG of UR (P <0. 001). A statistically significant correlation was found between CAS and UR (URall vs. CASall r = 0. 859,P <0. 001). After 12 weeks treatment with prednisone, the signs and symptoms of inflammation had lightened, UR pretreat vs. UR posttreat(t = 4. 39, P = 0. 007) ; CAS pretreat vs. CAS posttreat ( Z = - 5. 51, P < 0. 001 ).

Orbital scintigraphy with 99Tcm-octreotide is a method for judging activity of inflammation in TAO based on the distribution of somatostatin receptors, lymphocyte infiltration and fibroblast activating in retrobulbar tissue. There is a good correlation between CAS and UR. The scintigraphy can estimate activity of TAO and help to formulate therapy program and evaluate the therapeutic effects.