Cranial Bone Density and Scalp Perfusion in Positional Plagiocephaly: Quantitative Assessment Using Low-Dose Computed Tomography

Positional plagiocephaly is a common cranial deformity in infancy, but quantitative evaluation of cranial bone characteristics remains limited. This study aimed to assess cranial bone density and scalp perfusion in infants with positional plagiocephaly and to evaluate changes following helmet therapy using low-dose computed tomography (CT). A total of 61 infants with moderate to severe positional plagiocephaly who underwent CT for differentiation from craniosynostosis were retrospectively analyzed. Cranial bone density was quantified using Hounsfield units at standardized points around the lambdoid suture, and side-to-side differences were compared. In 10 infants, follow-up CT after helmet therapy and scalp perfusion measurements using laser Doppler flowmetry were also evaluated. The flattened side demonstrated significantly lower bone density than the contralateral side (P<0.001). In addition, scalp perfusion was reduced on the flattened side (P<0.01). Following helmet therapy, both bone density and scalp perfusion showed significant improvement. Low-dose CT enabled clear visualization of cranial sutures with minimal radiation exposure. These findings suggest that positional plagiocephaly is associated with localized reductions in bone density and perfusion, which may be reversible with treatment. Low-dose CT is a useful, practical tool for both diagnosis and quantitative evaluation in infants with cranial deformities.