Shear wave elastography in infantile fibromatosis colli: associations with clinical severity and short-term outcomes

Purpose: This study evaluated shear wave elastography (SWE) in infants with fibromatosis colli by assessing the associations of ultrasonography (US) and SWE with clinical severity and outcomes.Methods: This retrospective study included infants with fibromatosis colli who underwent US with SWE between June 2019 and December 2021.Lesion size and longitudinal extent of sternocleidomastoid involvement were measured, with extent categorized using a four-point scale (<25%, 25%-49%, 50%-74%, and ≥75%).SWE parameters included mean and median elasticity and the elasticity ratio (E-ratio; mass/normal muscle).Clinical severity was classified as mild or severe and 3-month outcomes as improved or non-improved.Associations of imaging parameters with clinical severity and outcomes were analyzed.Results: Thirty-five infants (mean age, 1.1±1.4months; 19 male infants) were included; 21 had mild and 14 severe disease.Of these, 29 underwent approximately 3-month follow-up, with 16 classified as improved and 13 as non-improved.Baseline extent scores and E-ratios were higher in the severe group (P=0.009 and P=0.004, respectively) and correlated with clinical severity (r=0.50,P=0.002; r=0.41,P=0.016, respectively).The non-improved group had higher baseline mean and median elasticity (24.35/23.70 vs. 18.02/16.61kPa, P=0.037/P=0.032)and a higher E-ratio (3.09 vs. 1.90, P=0.002).The E-ratio had an area under the receiver operating characteristic curve of 0.81 and remained associated with non-improvement after age adjustment (odds ratio, 3.73; 95% confidence interval, 1.57 to 12.29; P=0.009).Conclusion: In infantile fibromatosis colli, longitudinal extent and E-ratio were associated with baseline clinical severity.SWE-derived stiffness measures, particularly E-ratio, were associated with shortterm outcomes.