Background : Preoperative perforator localization of anterolateral thigh flap has been a challenge because of their topographic variation. However, as the more information of perforators can be obtained in the planning stage with the use of multidetector-row CT(MDCT), traditional techniques in perforator flap surgery would be changed and refined.

Methods : From November 2005 to August 2007, free anterolateral thigh(ALT) flap transfers were performed in 23 patients for reconstruction of the head and neck(23 cases). There were 17 male, 6 female patients with an average age of 50.1 (29-74). The mean BMI value of patients was 23.6 . Etioligies included 13 tongue cancer, 2 retromolar trigone cancer, 2 buccal cancer, 2 tonsilar cancer, 1 glottic cancer, 1 eyelid cancer. 1 lacrimal gland cancer, 1 malignant histiofibrocytoma . All patients underwent MDCT angiography for preoperative perforator mapping. In the axial view we studied the course of the lateral branch of lateral circumflex femoral artery from its origin. We identified the suitable perforators, marked them with an arrow. Then, locations of marked perforators were measured in 3-dimensional(3D) reconstruction image and transferred to the patient using anatomical landmarks. CT findings were compared with acoustic Doppler and intraoperative findings.

Results : Flap sizes ranged from 5x3cm to 16x9cm . One to two perforators(mean : 1.56) were marked on 3D CT image for each thigh, and the locations were in good correlation with hand-held Doppler examination. Intraoperatively, all perforators marked were confirmed and no additional perforators that were not identified on CT images were seen. All flaps survived completely. Donor site was primarily closed in 19 cases and Purse-string method was used in 4 cases. Mean length of donor site scar was 14.1cm (3.2-23cm). The average ratio of the long axis of the flap and the donor site scar was 1.95(0.81-3.09). Knowledge of the exact location and number of perforators allows minimized incision for flap harvest even in small flap and planned usage of multiple perforators for better perfusion or complex design.

Conclusions : Perforator mapping with preoperative MDCT angiography is valuable for the planning and executing the ALT flap transfer. By deciding preoperatively which perforators are most suitable, the surgeon can proceed directly to the chosen perforator with confidence and ligate other perforators safely and quickly. And the surgeon could select better donor site after comparing left and right thigh. Preoperatively, the surgeon can detect potent vascular disease and anatomic variation.Because the images of CT distribute from abdomen to whole legs, the surgeon also have informations about other possible flaps (DIEP flap, fibular osteocutaneous flap). Time saved in the operating room should be balanced with the extra cost of the investigation. Using the correct perforator topographic information allows safe, straightforward harvest and elegant reconstruction with leaving reduced donor site morbidity.

(Figure 1) Preoperative MDCT image of both thigh

(Figure 2) Intraoperative confirmed perforator of ALT free flap

(Figure 3) Donor site closed with Purse-String method.