Photoacoustic Tomography Shows the Branching Pattern of Anterolateral Thigh Perforators In Vivo

Summary: The distal branching pattern of perforators is associated with thin anterolateral thigh flap failure. The purpose of this study was to investigate the feasibility of using photoacoustic tomography as a diagnostic imaging modality to identify anterolateral thigh perforators and their branching patterns in the subcutaneous layer. Ten thighs in five healthy men were studied. The anterolateral aspect of the midthigh was examined using photoacoustic tomography. The correlation between photoacoustic tomography and ultrasound findings was evaluated. To determine the detectability of photoacoustic tomography by depth, the depth of vessels in the stem portion was compared to the depth of the deep fascia measured by ultrasound. Branching patterns of vessels in the adipose and suprafascial layers were evaluated by three-dimensional observation. A total of 18 perforators were visualized by photoacoustic tomography. Photoacoustic tomography and ultrasound had comparable diagnostic potential for the detection of perforators. Photoacoustic tomography visualized microvessels in the subcutaneous layer, especially those in oblique or horizontal orientations. The estimated mean depth of visualized vessels was 9 mm; the maximum depth was 13 mm. There was a strong correlation between the depth of visualized vessels in the stem portion and the depth of the deep fascia. Three-dimensional observation of photoacoustic tomographic images showed the branching morphology of perforators. This study showed the applicability of photoacoustic tomography to identification of the branching patterns of anterolateral thigh perforators in vivo, although limited visualization of subfascial vessels is a technical issue. The authors believe that photoacoustic tomography has the potential to be a new imaging modality for thin anterolateral thigh flap surgery. CLINICAL QUESTION/LEVEL OF EVIDENCE: Diagnostic, IV.