Smartphone-based thermal imaging for pedicled skin flaps: a pilot study toward objective perfusion assessment in facial, head, and neck reconstruction.

Purpose: This study aims to develop a practical algorithm for utilizing smartphone-based thermal imaging (SBTI) in the perioperative setting and to establish a standardized evaluation method for objectively assessing SBTI images for cutaneous perfusion of pedicled flaps in the face, head, and neck.

Methods: This prospective conducted study, integrated SBTI into the assessment of 16 patients undergoing reconstructive surgery for face and neck defects. Thermal images were captured at four timepoints: after marking (T1), after flap elevation (T2), upon completion of surgery (T3), and 24 h postoperatively (T4). The flap areas were divided into three flap zones and graded based on temperature differences (ΔT), with a grading system where grade 1 indicated perfect perfusion and grades 2 to 5 indicated increasing perfusion impairment.

Results: 6 male and 10 female patients aged 64-93 years (mean 78.5 years) undergoing reconstructive pedicled skin flap surgery for facial and neck defects (1 × 1 cm to 11 × 8 cm) due to diagnoses of malignant cutaneous lesions were investigated. Intraoperative assessments indicated good perfusion across flaps. One postoperative dehiscence occurred in an 83-year-old male with a cervical advancement flap, correlated with a significant temperature difference (ΔT > 4 °C) intraoperatively. Statistical analysis revealed a strong positive correlation (p = 0.0003) between clinical assessment grades and ΔT values between specific flap zones at T3.

Conclusion: SBTI is an easy-to-apply, low-cost, real-time and reproducible technique for indirect perfusion assessment in pedicled skin flaps of the head and neck region. Further studies are needed implementing this methodology in large and free flaps.