Preparation And Applied Value Of Somatostatin Receptor Imaging Agent In Patients With Graves' Ophthalmopathy

Graves'ophthalmopathy is one the most frequent complication of Graves'disease which characterized by eye proptosis,In the early stage of the disease, the retrobulbar infiltration is characterized by lymphocytes and interstitial edema, whereas in later stages fatty infiltration and fibrosis occur. So it will effect severely life and work of those patients. The clinical examination often fails in defining the stage of the disease and particularly the presence or not of fibrosis. In fact, the treatment of Graves'ophthalmopathy varies from immunosuppressive to surgical therapy . Immunesuppressive drugs are used to control GO, but they often do not provide satisfactory results. Therefore, to decide which treatment should be given is important to determine the clinical phase of the disease in the individual patient. Studies demonstrated that SST and its receptor genes are expressed on primary fibroblast cultures from retro-orbital tissues of GO patients. Because the presence of activated lymphocytes in the orbits represents the main target of corticosteroid therapy, and these cells can be revealed by SRS.AIM:The aim of the current study was to evaluate the potential role of orbital ^99mTc-octreotide uptake in predicting the response to corticosteroid therapy in patients with Graves'ophthalmopathy. There are great role that SPECT/CT fusion images is applied in GO and there are little reports published about this in internal journal.METHODS:OCT was labeled with ^99mTc by a direct method,the labeling rate was determined with Xinhua I chromatography . The radiochemical property of ^99mTc-OCT were evaluated by Sep Pak Cl8 chromatography, the cysteine challenge experiment,the serum incubation test and the stability experiment in vitro . There are 15 patients with Graves'ophthalmopathy (GO) and 4 volunteers (control group,CG) without eye disease or GD in the study. Single photon emission computed tomography(SPECT),computed tomography(CT) and left/right lateral position planar imaging of the head were obtained 4h after the iv injection of 740MBq of ^99mTc-OCT, corticosteroid therapy (methylprednisolone, 10mg, qo, tid, 1 month) was given for all patients at the next day. In all patient SRS was performed again after 1 month. Radioligand uptake within each orbit (O) and occipital (OC) was measured using the region of interests (ROI) method and the O-to-OC ratio was determined before and after corticosteroid treatment. Clinical activity of Graves'ophthalmopathy was evaluated before and after treatment by calculating the ophthalmopathy index(OI).RESULTS:1. Using stannous tartrate as reductant,OCT was successfully labeled by ^99mTc. And we acquired a labelling efficiency of 95%, specific activity 21.9 PBq/mmol; 2. Even 4 hours later in room temperature , the labelling efficiency of ^99mTc-Octreotide still > 90%;3. The labeling rate of ^99mTc-OCT was 94.4% and free ^99mTc was 0.5% in the cysteine challenge experiment. There was unobvious combination found between ^99mTc-OCT and serum protein;4. A significant change of O/OC ratio was observed between Pretreatment and posttreatment in 12 patient with active GO(1.64±0.13 vs. 1.21±0.09, P<0.05), and in those CG (1.16±0.04, P<0.05) at the scintigraphy. Not significant change of O/OC ratio was observed between CG and posttreatment GO(1.16±0.04 vs.1.21±0.09,P>0.05 ). As well as not significant change of O/OC ratio was observed in 3 patient with inactive GO(P>0.05) both pretreatment and posttreatment, and in those CG ( P>0.05 ) .CONCLUSION:1. ^99mTc-OCT can be readily prepared,the labeling yields are quite high (>95%),and stability in vivo(vitro);2. In patient with active Graves'ophthalmopathy, SRS showed markedly increased orbital uptake of ^99mTc-OCT. The study demonstrated that ^99mTc-OCT scitigraphy is able to predict the clinical response to corticosteroid therapy in patient with GO , and may be considered an objective and safety approach to select the patient for the proper treatment;3. It is a significance work that SPECT/CT fusion images is applied in GO,because the fusion imaging can to solve the problem that anatomic structure of nuclear medicine imaging isn't sharped,and it can enhance the capability of diagnosis of desease.