Preoperative vascular mapping for anterolateral thigh flap surgeries: A clinical trial of photoacoustic tomography imaging

Abstract

Background Photoacoustic tomography (PAT) is a noninvasive vascular imaging modality that uses near‐infrared pulse laser beams and ultrasound (US) to visualize vessels. We previously demonstrated the utility of PAT for visualizing anterolateral thigh (ALT) perforators in a clinical study of 10 thighs in 5 healthy adults. Evaluation of the correlation between PAT and US findings showed that PAT had comparable diagnostic potential but was superior in visualizing subcutaneous microvessels; however, there was no comparison with intraoperative findings. In this study, we used a newly developed technique to transfer a PAT image to a body‐attachable transparent sheet to compare PAT and intraoperative findings. Methods Eight patients were recruited in this prospective study. Patient age ranged from 32 to 79 years (average 60). Seven ALT flaps were applied in head and neck reconstruction. One flap was elevated in chest wall reconstruction. Each PAT scan of an 18 cm × 13.5 cm region took approximately 5 min. Acquired data were processed three‐dimensionally using a novel imaging software program. Perforator vessel data from PAT imaging were traced and corrected for projection onto medical film sheets. The correlation between the perforator stem portions predicted by PAT and the intraoperative findings at the level of the fascia‐penetrating points was evaluated, and distal branching patterns were analyzed. Results PAT imaging showed 16 perforators in 8 thighs. Intraoperative surgical findings revealed that all the perforator penetrating points at the deep fascia level matched the PAT findings within 10 mm. None of the eight ALT flaps demonstrated postoperative complications. The perforator complexes were classified as type I in three cases (19%), type II in eight cases (50%), and type III in five cases (31%). Conclusions PAT imaging matched the intraoperative findings within 10 mm. Preoperative vascular evaluation allows for the creation of a vascular map for facilitating ALT flap surgeries.

Photoacoustic microscopy: a novel approach for studying perforator skin flap in a mouse model

“…Additionally, they involve high costs, have a limited observation window, expose patients to radiation, and can fail to accurately visualize the perforasome of individual perforators due to their limited resolutions. Meanwhile, infrared thermography, which has been described previously by researchers (26), can automatically and reliably detect the perforators in thermograms, but the detailed information produced cannot be clearly visualize. Moreover, photoacoustic tomography, as a branch of photoacoustic image technology, was previously used to identify the location of the anterolateral thigh perforator in clinical study; however, due to its poor resolution and contrast, it is difficult to visualize very small perforators or the clear boundary of perforators, which can significantly limit the perforator flap design.…”

Technological advancements in head and neck free tissue transfer reconstruction

“…Photoacoustic tomography (PAT) is a 3-dimensional (3D) vascular mapping technology that has recently been used in preoperative planning for flap harvest [16,17] . This technology uses energy from a near infrared pulse laser which is absorbed by hemoglobin.…”

“…This technology can be particularly useful in the harvest of perforator based ALT free flaps due to its ability to map the supra-fascial course of the vessels. Tsuge et al [16] showed PAT is comparable to ultrasound in the evaluation of supra-fascial perforator branching patterns and is better than ultrasound at showing oblique and horizontally oriented branches. This can be particularly useful in the process of thinning ALT flaps to expand its utility in defects requiring a thin flap [18] .…”

“…This can be particularly useful in the process of thinning ALT flaps to expand its utility in defects requiring a thin flap [18] . PAT is limited in its ability to examine branching patterns deep to the fascia and is also unable to distinguish arteries from veins [16] .…”

“…PAT is a newer technology still under development. One of its main limitations for clinical use is the lack of anatomical reference points precluding its intraoperative use [16] . Tsuge et al [17] attempted to address this in their clinical trial by developing a transparent sheet with mapping that could be sterilized and used intraoperatively.…”