Preoperative perforator mapping of anterolateral thigh perforators via Projected Augmented Reality and Dynamic Infrared Thermography.

Background: The anterolateral thigh (ALT) flap is a reliable and versatile flap with the ideal characteristics for soft-tissue reconstruction. However, as it is known for its highly variable anatomy, it requires preoperative perforator localization to optimize flap design and dissection of the flap. Dynamic Infrared Thermography (DIRT) is a non-invasive and quick imaging method that provides real-time information. This study aimed to provide a proof-of-principle for the feasibility of projecting DIRT hotspots directly onto patient's skin before ALT flap harvest.

Methods: The portable and self-aligning projection device prototype (Anatomy Projector) with an embedded thermal sensor was used to obtain and automatically project thermal images of DIRT on the patient's thigh before ALT flap dissection. Preoperatively projected DIRT hotspots were validated using a hand-held Doppler (HHD) and compared with the locations of intraoperative perforators.

Results: A total of 133 DIRT hotspots were projected in 20 patients, of which 97.3% could be verified with HHD within a 1 cm radius. Intraoperative measurements identified 26 perforators, of which 53.8% could be matched to a DIRT hotspot within a 1 cm radius, 76.9% within a 2 cm radius, and 92.3% within a 3 cm radius.

Conclusion: This study highlights the clinical applicability of projecting thermal images directly onto a patient's thigh before ALT flap reconstruction. Visualization of DIRT hotspots simplifies perforator localization and provides high consistency with Doppler and intraoperative findings. Future research should explore its applicability for the intraoperative- and postoperative settings as well as other fields of plastic surgery.