“…The imaging techniques, including magnetic resonance imaging, near-infrared spectroscopy, laser Doppler flowmetry, surface thermometry, and continuous tissue oxygenation tension measurement, are expensive or require special equipment. By contrast, the operative techniques, which entail externalizing a component of the flap for monitoring, have the advantages of design simplicity and the ability to allow continuous monitoring (Lin et al, 2014;Tan et al, 2012).…”