Comparative Evaluation of 68Ga-FAPI and 68Ga-DOTATATE PET/CT and PET/MRI in Thyroid Eye Disease

Condition(s) studied

Investigational drug(s) / intervention(s)

68Ga-FAPI PET/CT and PET/MR Imaging: Participants receive 3 to 5 mCi of 68Ga-FAPI intravenously. PET/CT and PET/MR imaging of the head and orbits is performed approximately 50 minutes after injection, with PET acquisition of approximately 5 minutes per bed position. PET/MR includes routine T1-weighted, T2-weighted, and FLAIR sequences. The exact FAPI compound should be added if specified by the radiopharmacy documentation. Required confirmation: the protocol does not identify the specific FAPI compound, such as FAPI-04.

68Ga-DOTATATE PET/CT and PET/MR Imaging: Participants receive 3 to 5 mCi of 68Ga-DOTATATE intravenously. PET/CT and PET/MR imaging of the head and orbits is performed approximately 50 minutes after injection, with PET acquisition of approximately 5 minutes per bed position. PET/MR includes routine T1-weighted, T2-weighted, and FLAIR sequences.

Study summary

Thyroid eye disease is an autoimmune disorder that can cause inflammation and fibrosis of the extraocular muscles and orbital tissues. Accurate assessment of disease activity is important for treatment planning, but commonly used clinical scores and conventional imaging each have limitations.

This prospective single-center cohort study will evaluate two molecular imaging approaches, gallium-68-labeled fibroblast activation protein inhibitor (68Ga-FAPI) PET/CT and PET/MR and gallium-68 DOTATATE somatostatin receptor PET/CT and PET/MR, in adults with thyroid eye disease and in a control group without thyroid-related or orbital disease. The study will compare visual and quantitative imaging findings, including maximum standardized uptake value and target-to-background ratio in the extraocular muscles, and examine their associations with clinical activity score and extraocular muscle thickness. The study aims to characterize the ability of these imaging methods, separately and in combination, to assess thyroid eye disease activity.

Eligibility

Primary outcome measure(s)

• Extraocular Muscle SUVmax on 68Ga-FAPI and 68Ga-DOTATATE PET Imaging — At each imaging examination performed within the protocol-defined 1-week imaging period
  Maximum standardized uptake value will be measured separately in the superior, medial, lateral, and inferior rectus muscles on PET/CT and PET/MR images for each tracer. Values will be summarized by tracer, imaging platform, eye, and participant group.
• Extraocular Muscle Target-to-Background Ratio on 68Ga-FAPI and 68Ga-DOTATATE PET Imaging — At each imaging examination performed within the protocol-defined 1-week imaging period
  For each extraocular muscle, target-to-background ratio will be calculated as extraocular muscle SUVmax divided by background SUVmax measured using a 1-cm region of interest in occipital soft tissue. Values will be summarized by tracer, imaging platform, eye, and participant group.

Trial sites (1)

More Daping Hospital and the Research Institute of Surgery of the Third Military Medical University trials in China

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