CTR-FAPI-guided Precision Surgery for Newly Diagnosed MTC

Inclusion Criteria:

* Newly-diagnosed medullary thyroid carcinoma meeting either criterion a or criteria b + c:

  1. Pathologically or cytologically confirmed diagnosis;
  2. Elevated serum calcitonin level (\>10 pg/mL);
  3. Other infectious or neoplastic diseases excluded.
* Life expectancy ≥ 12 weeks;
* ECOG performance status of 0 or 1;
* Absence of distant metastasis confirmed by conventional imaging, with resectable locoregional disease;
* Scheduled to undergo surgery within 30 days;
* Females of childbearing potential must use effective contraception (e.g., sterilization, intrauterine device, condoms, oral/injectable contraceptives, abstinence, or partner vasectomy) during the study and for 6 months after study completion. Male participants must agree to use effective contraception during the same period;
* Capable of understanding and voluntarily signing the informed consent form with good compliance.

Exclusion Criteria:

* History of prior treatment for medullary thyroid carcinoma (e.g., surgery, radiotherapy, targeted therapy, radionuclide therapy, or interventional therapy).
* Major organ dysfunction, defined as:

  1. Bone marrow impairment: WBC ≤ 4.0×10⁹/L or neutrophils ≤ 1.5×10⁹/L; platelets ≤ 100×10⁹/L; hemoglobin ≤ 90 g/L
  2. Hepatic impairment: PT or APTT ≥ 1.5 × ULN; total bilirubin ≥ 1.5 × ULN; ALT/AST ≥ 2.5 × ULN (or ≥ 5 × ULN in participants with liver metastases); ALP ≥ 2.5 × ULN (or ≥ 4.5 × ULN in cases with bone or liver metastases)
  3. Renal impairment: BUN ≥ 1.5 × ULN; serum creatinine ≥ 1.5 × ULN
* Women who are planning pregnancy, currently pregnant, or breastfeeding.
* History of other malignant tumors;
* Inability to lie flat for at least 30 minutes;
* Known allergy to contrast agents;
* Claustrophobia or other psychiatric disorders that may preclude compliance with study procedures;
* Unwillingness to participate in the clinical trial;
* Assessed as not being a surgical candidate or refusal to undergo surgery;
* Any other condition deemed by the investigator to make the participant unsuitable for the study.