The Ability of Intra-operative Perfusion Mapping with Laser-assisted Indocyanine Green Angiography to Predict Mastectomy Flap Necrosis in Breast Reconstruction: a Prospective Trial

Mastectomy skin flap ischaemia leading to necrosis is a common occurrence. Laser-assisted indocyanine green (ICG) angiography can assist to locate these poorly perfused areas intra-operatively. Our study aims to identify specific perfusion values produced by ICG angiography that accurately predict mastectomy flap necrosis. A total of 42 patients undergoing autologous or implant-based breast reconstruction had mastectomy flaps imaged using laser-assisted ICG angiography at the completion of reconstruction. Intra-operative perfusion values were correlated with postoperative skin flap outcomes. Risk factors for abnormal perfusion were recorded and analysed. A total of 62 breast reconstructions were imaged, including 48 tissue expander reconstructions, six transverse rectus abdominis myocutaneous (TRAM) flaps, six deep inferior epigastric perforator (DIEP) flaps and two direct-to-implant reconstructions. Eight cases (13%) of full-thickness skin necrosis were identified postoperatively. A SPY Elite(®) value of ≤ 7 accurately predicted the development of flap necrosis at 88% sensitivity and 83% specificity. False-positive cases (those with perfusion values ≤ 7 which did not develop necrosis) were more likely to have a smoking history and/or to have had an epinephrine-containing tumescent solution used during mastectomy. Excluding patients with smoking or epinephrine use, a SPY value of ≤ 7 predicted flap necrosis with a sensitivity of 83% and specificity of 97%. Thus, these data suggest that laser-assisted ICG angiography predicts postoperative outcomes with high accuracy. In our series, a SPY value of ≤ 7 correlated well with mastectomy flap necrosis. Furthermore, smoking and intra-operative injections containing epinephrine should be considered when evaluating low perfusion values as they can lead to false-positive test results.