Volumetric Feasibility of Lumbar Artery Perforator Flaps Compared to Abdominal Flaps for Breast Reconstruction in Low-BMI Patients: A CT-Based Study

Background: Although abdominal flaps remain the gold standard for autologous breast reconstruction, their use in low-BMI patients—particularly in bilateral cases or when matching a contralateral large breast—can be limited by concerns about insufficient volume. The lumbar artery perforator (LAP) flap has emerged as a potential alternative. This study evaluated its volumetric adequacy in lean patients using computed tomographic angiography (CTA)-based analysis. Methods: Between 2019 and 2024, patients with BMI ≤ 25 who underwent abdominal flap-based breast reconstruction were retrospectively reviewed. Flap volumes were assessed using CTA. LAP flap volumes were compared with (1) 50% of estimated abdominal flap volume to simulate bilateral reconstruction and (2) estimated abdominal flap volumes based on inset rates from bipedicled cases. Comparisons were stratified by BMI: < 23 and 23–25. Results: A total of 177 patients were included. The estimated abdominal and LAP flap volumes were 695.0 and 486.6 cm³, respectively, both positively correlated with BMI. The LAP-to-abdominal flap volume ratio increased as BMI decreased. LAP flap volume exceeded 1.0 relative to 50% of abdominal volume in over 90% of cases, especially in the BMI < 23 group. In bipedicled DIEP flap cases, the average abdominal inset ratio was 0.84; accordingly, the adjusted LAP-to-abdominal flap volume ratio was 0.87 overall and 0.92 in the BMI < 23 group. Conclusions: The LAP flap volume was found to be comparable to that of the abdominal flap in a meaningful proportion of lean patients. These findings suggest it may serve as a reasonable alternative in cases requiring bilateral or bipedicled abdominal flap reconstruction. Level of Evidence III: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.