This is a single-center prospective study designed to develop and validate an individualized, low-dose indocyanine green (ICG) protocol for near-infrared fluorescence cholangiography during emergency laparoscopic cholecystectomy in patients with moderate to severe acute cholecystitis.

The main problem we aim to solve is that inflammation in the bile duct wall often makes standard ICG doses ineffective for clear visualization. We will use pre-operative MRI to measure the thickness of the common bile duct (CBD) wall, then calculate a personalized ICG dose using a simple formula. We will first test and refine this formula in a small group of patients, then verify its effectiveness in a second group. The goal is to achieve clear, high-contrast imaging of the bile ducts, which helps surgeons operate more safely and accurately.

All patients will receive a low, personalized dose of ICG given by vein 1 hour before surgery. We will evaluate how well the bile ducts show up on the fluorescence images, as well as safety and effectiveness outcomes. This study will provide a practical, patient-tailored solution for improving bile duct visualization in emergency gallbladder surgery.

Inclusion Criteria:

• Patients aged ≥18 years undergoing emergency laparoscopic cholecystectomy.
• Diagnosis of moderate to severe acute cholecystitis according to the 2018 Tokyo Guidelines.
• Preoperative MRI available for common bile duct wall thickness measurement.
• Ability to provide informed consent.

Exclusion Criteria:

• Known allergy or contraindication to indocyanine green (ICG).
• Severe renal or hepatic dysfunction (eGFR <30 mL/min/1.73m² or Child-Pugh class B/C cirrhosis).
• Pregnancy or breastfeeding.
• Previous biliary surgery or known choledocholithiasis requiring preoperative intervention.
• Unstable hemodynamic status requiring conversion to open surgery before ICG administration.