Detection of Perforators for Free Flap Planning Using Smartphone Thermal Imaging: A Concordance Study with Computed Tomographic Angiography in 120 Perforators

Summary: Design and preoperative planning of microsurgical flaps are fundamental steps for successful surgery. Currently, computed tomographic angiography is considered the gold standard, and new technologies such as thermography could complement its usefulness. The aim of this study was to determine the concordance between thermographic images obtained with a smartphone thermal camera and computed tomographic angiography for detecting perforators using the anterolateral thigh flap area as a model. A concordance study of diagnostic tests was performed in patients who underwent limb reconstruction in 2016. Perforators identified in thigh computed tomographic angiographic images and hotspots on thermographic images obtained by means of the FLIR ONE smartphone camera were compared based on the distance from the anterior superior iliac spine. The authors studied 20 patients, including 38 anterolateral thigh flap territories in total, and identified 117 perforators by computed tomographic angiography and 120 hotspots by thermography. The average mean distance from the anterior superior iliac spine using these methods was 193.14 mm, and the mean difference in distance was 2.37 mm, with both measurements being obtained within a radius of 20 mm, with a concordance kappa index of 0.975 ( p < 0.001). Thermographic imaging presented a sensitivity of 100 percent and a specificity of 98 percent in detecting perforators. Thermographic images obtained with a smartphone thermal camera have a high concordance with the method considered the gold standard for perforator detection. In addition, its sensitivity and specificity are comparable to those of computed tomographic angiography, which makes it a very useful method for mapping perforators in free flap planning. CLINICAL QUESTION/LEVEL OF EVIDENCE: Diagnostic, II.