Currently during DIEP flap reconstruction, the perfusion of the flap is assessed by the clinical view of the surgeon. Identification of demarcated ischemic zones of the DIEP flap could be optimized by using fluorescence imaging with indocyanine green (ICG) in order to lower the rate of fat necrosis. This study evaluates whether intraoperative perfusion assessment with ICG fluorescence imaging causes a lower rate of fat necrosis compared to conventional intraoperative clinical evaluation of DIEP flaps.

Rationale: Autologous breast reconstruction after mastectomy due to cancer or prophylactically due to genetically increased risk is frequently performed. A complication that may occur after a deep inferior epigastric artery (DIEP) reconstruction is the occurrence of fat necrosis in the transplanted flap due to ischemia (reperfusion injury). Identification of deep inferior epigastric artery perforators and identification of demarcated ischemic zones of the DIEP flap can be optimized by using fluorescence imaging with indocyanine green (ICG), as has been demonstrated in previous studies. This could result in less fat necrosis, less partial flap loss, and other complications. A randomized controlled trial would be the best study design to assess the value of ICG in determining the perfusion of DIEP flaps, thereby reducing the occurrence of fat necrosis and other complications.

Objective: To determine whether fluorescence imaging using ICG for the assessment of DIEP flap perfusion during surgery decreases the occurrence of fat necrosis compared to standard intraoperative clinical assessment of DIEP flap perfusion.

Study design: This is a two-armed randomized controlled trial:

• interventional arm: evaluation of flap perfusion based on 1) clinical parameters, and 2) fluorescence imaging using ICG
• conventional arm: evaluation of flap perfusion based on clinical parameters only

Study population: Patients scheduled for elective surgery for autologous breast reconstruction, uni- or bilateral, using DIEP or muscle sparing transverse rectus abdominis muscle (msTRAM) flaps. Female patients 18 years of age and older.

Intervention (if applicable): evaluation of flap perfusion based on 1) clinical parameters, and 2) fluorescence imaging using ICG

Main study parameters/endpoints: Difference in percentage of fat necrosis after autologous breast reconstruction using DIEP flaps between patients in whom fluorescence imaging was used and patients in whom flaps were clinically assessed.

Inclusion Criteria:

1. Female patients 18 years of age and older
2. Who underwent a mastectomy for breast cancer or prophylactic due to genetic predisposition
3. Patients scheduled for elective surgery for autologous breast reconstruction, uni- or bilateral, using DIEP or msTRAM flaps. In case of bilateral breast reconstruction the flaps should be bilateral anastomosed.
4. Written informed consent

Exclusion Criteria:

1. Allergy to ICG, iodine or shellfish
2. Any medical condition that in the opinion of the investigators could potentially jeopardize the safety of the patient
3. Impaired renal function defined as eGFR< 50 mL/min/1.73m2 (this can be seen in the standard preoperative lab results)

The participant is blinded for the study arm. A second evaluator of postinterventional fat necrosis is blinded for the study arm.