Highlight
– The SPY-PHI Quantitative Perfusion (QP) tool provides real-time, numeric assessment of mastectomy skin flap perfusion during staged breast reconstruction.
– A perfusion threshold of approximately 30% predicts skin necrosis risk with high sensitivity and specificity in untreated tissues.
– Nitroglycerin ointment use confounds perfusion assessment, attenuating the correlation between low perfusion and necrosis.
– This prospective evaluation lays foundational evidence supporting quantitative thresholds to guide intraoperative decision-making and reduce wound complications.

