The research aims to prospectively include patients with GEP-NENs, undergo preoperative imaging assessment (including PET/CT and contrast-enhanced CT), and accurately delineate lymph node regions. Through postoperative pathological reports, the diagnostic performance of lymph node metastasis (LNM) in GEP-NENs is evaluated. Factors influencing the diagnostic accuracy of SSTR-PET/CT and contrast-enhanced CT are also investigated.

Inclusion Criteria:

1. Age > 18 years old;
2. Patients diagnosed with GEP-NEN by surgical pathology;
3. Complete medical records including basic information and treatment process;
4. Patients who have undergone preoperative contrast-enhanced CT and 68Ga-SSTR-PET/CT, and have consented to the 68Ga-SSTR-PET/CT project in the Nuclear Medicine Department.

Exclusion Criteria:

1. Presence of concomitant malignancies;
2. Cases diagnosed pathologically as non-GEP-NEN.

Patients with GEP-NEN undergoing surgical treatment at Peking Union Medical College Hospital.