**3.1 Preoperative localization of DIEP flap perforator**

Patients in the US group had US examinations the day before the surgery, with the US group getting surface markings of perforator arteries directly under color doppler ultrasound guidance. CT vascular imaging examinations were done in the CT room for the CTA group, and the physician duplicated the DICOM files and loaded them into the HOROS program on their mobile phone or a personal computer. The imaging processing system was used to determine the dominant perforator, and the position of the chosen dominant perforator was written on the body surface centered on the level of the umbilicus.
