Preoperative Ultrasound Measurement of Subplatysmal Fat Thickness as a Predictor of Excision Volume in Neck Contouring Surgery: A Quantitative Analysis

Accurately quantifying subplatysmal fat before neck lift surgery remains challenging, limiting surgical planning precision. This study developed and validated a predictive model using preoperative ultrasound measurements to estimate intraoperative fat excision volume. A retrospective analysis of 130 consecutive patients (94 females, 36 males; mean age 32.2 years) undergoing neck lift with subplatysmal fat excision was performed. High-frequency ultrasound measured subplatysmal and subcutaneous fat thickness preoperatively. Excised volume was quantified using saline displacement. Pearson correlation and multivariate regression identified predictors. Rigorous validation included bootstrap analysis, stratified 10-fold cross-validation (repeated 100 times), and temporal validation. Mean subplatysmal thickness was 5.09±1.73 mm, and mean excised volume was 5.95±2.18 cc. Subplatysmal thickness demonstrated a strong correlation with excision volume (r=0.595, P<0.001), as did BMI (r=0.572, P<0.001). The final regression model incorporating thickness (β=0.622, P<0.001), BMI (β=0.244, P<0.001), and gender (β=-0.657, P=0.033) explained 54.5% of variance. Validation demonstrated excellent model stability with bootstrap-validated R²=0.542 and consistent cross-validation performance (mean R²=0.348, SD=0.182). Temporal validation showed sustained accuracy (R²=0.458). Model calibration was excellent (slope=1.007, 95% CI: 0.882-1.118; intercept=0.00, 95% CI: -0.342 to 0.342), with 60% of predictions within ±1 cc. This validated predictive model provides a rigorously validated quantitative framework for estimating subplatysmal fat excision volume using readily available preoperative ultrasound measurements, significantly improving surgical planning accuracy and patient counseling. Further studies are warranted to correlate ultrasound-based predictions with postoperative aesthetic outcomes.