Evaluation of Inflammatory Activity of Extraocular Muscles in Thyroid Associated Orbitopathy by [68Ga]DOTATATE PET/CT.

Purpose: The accurate assessment of inflammatory activity of the extraocular muscles (EOMs) in thyroid associated ophthalmopathy (TAO) is crucial for formulating subsequent treatment strategies and prognostic judgments. This study aims to explore the efficacy of using [⁶⁸Ga]DOTATATE PET/CT to assess the inflammatory activity of EOMs in TAO patients.

Procedures: This study enrolled 22 TAO patients and 6 healthy volunteers, all of whom underwent orbital [⁶⁸Ga]DOTATATE PET/CT. Among these, 18 patients underwent orbital [^99mTc]DTPA SPECT/CT within one week, and the other 4 patients received orbital MRI. All imaging data were independently assessed, followed by comparative data analysis. The patients then received different treatment schemes, and their prognosis was followed up.

Results: [⁶⁸Ga]DOTATATE PET/CT could effectively evaluate the inflammatory activity of the EOMs in TAO patients and demonstrate good consistency with [^99mTc]DTPA SPECT/CT and orbital MRI, but show a better resolution to distinguish EOMs and surrounding structure. The receiver operating characteristic (ROC) curves for each EOM, treated as individual research units, exhibited an area under the curve (AUC) exceeding 0.9. The medial rectus demonstrated the highest involvement and diagnostic accuracy(AUC = 0.976, P < 0.001). Patients treated with glucocorticoids showed significantly higher SUVmax in EOMs compared to those receiving symptomatic treatment (P < 0.01).

Conclusions: [⁶⁸Ga]DOTATATE PET/CT is a reliable method for assessing the inflammatory activity of EOMs in TAO patients, providing strong objective evidence for the precise diagnosis and treatment.