Feasibility and flap viability assessment of axial pattern flap harvest in a free-style manner using photoacoustic tomography.

Introduction: An axial pattern flap is a single pedicled flap with anatomically recognized blood vessels running along its long axis, allowing it to be harvested with a considerably longer length than a random pattern flap. Distal necrosis is a concern when designing elongated flaps beyond the midline to cover large tissue defects. However, imaging modalities that visualize subcutaneous microvessels preoperatively in three dimensions with sufficient resolution are lacking, individual vessel anatomy is ignored and flaps are designed based on past anatomical research. In this preliminary study, we evaluated the feasibility of harvesting flaps, including an axial artery running across the midline delineated by photoacoustic tomography and its effect on flap viability. Methods: Six rats were divided into two groups: MCA group (flaps including the midline-crossing artery visualized by photoacoustic tomography running across the midline, Results: Preoperative photoacoustic tomography revealed the subcutaneous arteries crossing the midline and identified the location of the deep circumflex iliac perforator. The viability of flaps with MCA was better than that in the non-MCA group, although this difference was not statistically significant ( Conclusions: This proof-of-concept study suggests that photoacoustic tomography is a useful imaging modality for designing elongated free style flaps.