MRI Morphometry of the Pediatric Olfactory Bulb and Sulcus: Age-Related Changes and Reference Morphometric Values

Background: Reference morphometric data for the olfactory sulcus (OS) and olfactory bulb (OB) in the pediatric population are scarce. This study aimed to evaluate the age-related morphometric characteristics of these structures using magnetic resonance imaging (MRI). Methods: This retrospective cross-sectional study included pediatric patients with normal brain MRI findings. Olfactory bulb diameters and olfactory sulcus depth were measured. Patients were grouped by age, and correlation, group comparison, and regression analyses were performed to evaluate associations with age. Results: A total of 248 children were enrolled. The mean olfactory bulb transverse and craniocaudal diameters were 2.69 ± 0.67 mm and 2.15 ± 0.65 mm on the right and 2.85 ± 0.71 mm and 2.25 ± 0.63 mm on the left, respectively. The mean olfactory sulcus depth was 10.08 ± 1.76 mm on the right and 9.72 ± 1.65 mm on the left. Sulcus depth showed a weak positive correlation with age (right: r = 0.277, p < 0.001; left: r = 0.259, p < 0.001), whereas bulb measurements demonstrated weaker associations (e.g., right bulb craniocaudal diameter: r = 0.153, p = 0.016). Quadratic regression analyses indicated that age significantly predicted sulcus depth (explaining 27.1% and 25.5% of the variance on the right and left sides, respectively, p < 0.001), whereas bulb measurements remained relatively stable. Conclusion: OB dimensions are relatively stable across childhood, whereas OS depth increases with age in the pediatric population. These data provide reference morphometric parameters to support the radiological evaluation of olfactory system development in children.