| Objective The aim of this study is to analyze the feasibility of estimationactivity of TAO with orbital scintigraphy and the relativity between the orbitalscintigraphy and the clinical activity score (CAS), we studied the orbitalscintigraphy in patients with TAO and volunteers, and evaluated their orbitaluptake ratios of 99Tcm-octreotide. Methods There are 30 patients with TAO and 11 control volunteerswithout eye disease or Graves' disease. The patients was graded by CAS , 20patients in activity group (CAS≥3), 10 patients in inactivity group (CAS <3).SPECT (360°) and planar studies of skull were completed within 11.5 h after ivapproximately 740MBq(20mCi) 99Tcm-octreotide. We selected the best oneslice for displaying eye, which be used for the analysis of imaging. The ROI(regions of interest) of right orbit (R), left orbit (L) and occipital (O) were beendrawn in the imaging. The uptake ratios (UR) of R/O and L/O were calculatedfor semi quantitative analysis. Patients in activity group had acceptedimmunosuppressive therapy and processed scintigraphy after therapy. Thestatistical analyses were included ANOVA, Spearman regression analysis andpaired t-test using SPSS 10.0. Results 99Tcm-octreotide biokinetics in patients with TAO were as thesame as in control volunteers, showing a rapid blood clearance, the clearimaging of liver, kidney and bladder, and the agent evacuated by urinary system.In all control volunteers, the orbit appeared as a "cold area", and the orbituptake of inactive patients is little, whereas visual orbital accumulation of99Tcm-octreotide was found in patients with activity TAO(URact: 1.40±0.18vs. URcontr: 1.07±0.20; URact: 1.40±0.18 vs. URinact : 1.15±0.10 ; P<0.01,respectively; URinact: 1.15±0.10 vs. URcontr : 1.07±0.20, P>0.05 ). It isshowed that the patients with activity eye disease (n= 20) presented with anincreasing of 99Tcm-octreotide compared with control group, but there was nosignificant difference between the orbital uptake of the patients with inactivedisease and control volunteers. A statistically significant correlation was foundbetween CAS and the orbital uptake values (URall vs. CASall, r= 0.859; URact vs.CASact, r= 0.771; URinact vs. CASinact, r= 0.735).URpretreat vs. URposttreat,t= 4.39, P <0.05;CASpretreat vs. CASposttreat,Z= -5.51,P <0.01. Conclusions (1) Orbital scintigraphy with 99Tcm-octreotide displays thedistribution somatostatin receptors (SSTR) in retrobulbar tissue. We can inferlymphocyte infiltration and fibroblast activating in retrobulbar tissue and judgeactivity with TAO base on the distribution of SSTR at molecule level. (2) Wefound that 99Tcm -octreotide scintigraphy seems useful to predict a positiveresponse immunosuppressive treatment in patients with thyroid associatedophthalmopathy,and can help determining treatment regimen and evaluatetherapeutic efficacy.
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