Smartphone thermal imaging for preoperative perforator mapping in DIEP flap breast reconstruction

Abstract

Perforator-based flaps have become a mainstay of autologous breast reconstruction practice. Despite available radiological investigations ranging from Doppler ultrasound (US) to CT angiography (CTA), finding and quantitatively assessing perforators remains a time-consuming, complex process. Infrared thermographic imaging (IRT) shows promise as a novel modality for preoperative localisation of perforator vessels. Thirteen women undergoing elective breast reconstruction with deep inferior epigastric artery perforator (DIEAP) flaps were recruited between August 2017 and July 2018. All had CTA and Doppler US mapping of arterial perforators preoperatively as standard. Additional abdominal thermal images were taken using a FLIR ONE smartphone compatible camera. Thermal hotspots were compared with Doppler markings and CTA findings. Twenty-six flaps were analysed. Seventy perforators were marked by Doppler US, with a mean of 2.92 perforators per flap (± SEM 0.15, SD 0.72). Forty (57%) had a corresponding hotspot on IRT. Overall, there was a statistically significant positive correlation between the number of perforators detected by Doppler US and IRT (r = 0.573, n = 26, p = 0.003) and kappa index 0.65. Eighty-four perforators were identified by CTA, with a mean of 3.5 perforators per flap (± SEM 0.14, SD 0.66). Fifty-eight (69%) had a corresponding hotspot on IRT. There was a statistically significant positive correlation between the number of perforators detected by CTA and IRT (r = 0.504, n = 26, p = 0.012) and kappa index 0.60. Thermography is an inexpensive, portable, non-invasive imaging technique, which shows statistically significant correlation to CTA and Doppler US in mapping perforators. Level of evidence: Level IV, diagnostic study.