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.