Shear-Wave Elastography as an Objective Diagnostic Tool for Capsular Contracture After Breast Implant Surgery: A...

Background/Objectives: Capsular contracture (CC) is the most frequent complication of breast implant surgery, affecting up to 20% of augmentation and up to 40% of post-mastectomy reconstruction patients. Diagnosis relies on the Baker classification with poor interobserver reliability (κ = 0.55). This study evaluated shear-wave elastography (SWE) as an objective diagnostic tool for CC via quantitative measurement of periprosthetic capsule stiffness. Methods: A prospective single-center comparative study (Romania) enrolled 26 augmentation patients (50 breasts) with asymptomatic Baker I/II CC as controls, and 25 breasts with confirmed Baker III/IV CC in post-mastectomy reconstruction patients as the study group. Stiffness was measured using the SuperSonic MACH 30 platform (mean, median, min, max, SD in kPa). Analysis included Mann-Whitney U tests, ROC curves with bootstrapped 95% CIs, and Youden's J index. Confounder analyses (Spearman correlations, multivariable logistic regression, partial correlations) assessed the independence of SWE findings from implant depth, periprosthetic tissue thickness, region-of-interest (ROI) diameter, and body mass index (BMI). Results: All four primary stiffness parameters differed significantly between groups (p < 10^-11, r > 0.97). Control median stiffness was 32.6 kPa versus 138.0 kPa in the study group. All four parameters achieved outstanding discriminative performance (AUC 0.988-0.994); SWE median yielded the highest AUC (0.994; 95% CI 0.980-1.000). A threshold of 82 kPa provided 100% sensitivity, 98% specificity, and 100% NPV. Baker Grades III (~92 kPa) and IV (~147 kPa) also differed significantly (p = 0.0001). No covariate (implant depth, periprosthetic tissue thickness, ROI diameter, BMI) significantly influenced SWE values within either group (all intra-group Spearman ρ p > 0.05), and SWE median stiffness remained the sole significant predictor in the fully adjusted multivariable model (adjusted OR = 1.18, 95% CI 1.08-1.31, p < 0.001). Conclusions: SWE objectively differentiates normal periprosthetic capsules from clinically significant CC with outstanding accuracy. An 82 kPa median stiffness threshold offers a reproducible, non-invasive complement to the Baker classification and provides a foundation for elastography-based CC staging.