The Clinical Application Of Radioreceptor Imaging In The Diagnosis Of Thyroid Associated Ophthalmopathy (TAO)

Objective:To evaluate the99mTc-OCT SPECT imaging in the diagnosis of thyroid associated ophthalmopathy (TAO).Methods:19outpatients (38eyes) in Nuclear Medicine department whose main complaint is discomfort around eye area (tearing, photophobia, eye pain, changes in vision, eyelid contracture and exophthalmos) were underwent orbital99mTc-OCT SPECT.5healthy volunteers (10eyes) recruited (healthy control group) were underwent the same examination. Taking the EUGOGO clinical diagnostic criteria, all outpatients’eyes were divided into TAO group (30) and non-TAO group (8). According to its clinical activity score (CAS), the TAO group was divided into active group (24) and inactive group (6); and at the same time, the TAO group was divided into mild group (11) and moderate-severe group (19) by the disease severity. Then the ratios of the highest eye radioactive count (T) to the lowest occipital scalp radioactive count (B) in all eyes were calculated, as the eye99mTc-OCT intake. Receiver operating characteristic (ROC) analysis was employed to define the threshold value of T/B ratio.Results:There is a significant difference in T/B ratio between Non-TAO group and healthy control group (t=2.76, P=0.014), and a highly significant difference between TAO group and healthy control group (t=5.86, P<0.001). The significant difference in T/B ratios were still found between TAO group and non-TAO (t=2.78, P=0.009), while a highly significant difference also found between active group and inactive group (t=2.59, P=0.015). The area under the curve of ROC for TAO group and non-TAO group was0.821, and0.854for active group and inactive group; the threshold value of T/B ratio was1.637for identifying TAO, and its sensitivity、specificity and accuracy were83.3%、87.5%and84.2%; the threshold value of T/B ratio for distinguishing between active group and inactive group was1.674, and its sensitivity、specificity and accuracy was87.5%、83.3%and86.7%, respectively. Conclusion:99mTc-OCT SPECT imaging combined with semi-quantitative analysis can give more accurate diagnosis in identifying TAO and distinguishing active TAO, and it is helpful to guide the individualized treatment plan for TAO.