Human olfactory bulb morphometry and olfactory sulcus depth measurement in normosmia

Area of Science:

• Neuroimaging
• Olfactory Neuroscience
• Human Anatomy

Background:

• Olfactory bulb (OB) and olfactory sulcus (OS) morphology are crucial for olfactory function.
• Previous studies have lacked comprehensive, multiobserver assessments of these structures in normosmic adults.

Purpose of the Study:

• To conduct a detailed multiobserver magnetic resonance imaging (MRI) assessment of OB and OS morphology in normosmic adults.
• To establish the reliability of MRI-based measurements for OB and OS structures.
• To characterize OB and OS morphology and explore potential correlations with age and olfactory function.

Main Methods:

• Manual segmentation of high-resolution MRI scans from 118 normosmic adults by multiple observers.
• Assessment of interobserver reliability for OB volume, width, height, anterior-posterior diameter (APD), and OS depth.
• Statistical analysis to evaluate correlations between morphological parameters, age, and olfactory function.

Main Results:

• Generally acceptable interobserver reliability for OB morphology; excellent agreement for OS depth and APD.
• Single-observer assessment is sufficient for group-level OB morphology analysis.
• Right OS depth and left OB height decreased with age; right OS depth correlated with right OB volume and APD.
• No significant correlations found between olfactory function and OB morphological parameters.
• Consistent right-sided OS depth observed, indicating hemispheric asymmetry.

Conclusions:

• A standardized multiobserver workflow provides reliable assessment of OB and OS morphology.
• Comprehensive characterization of OB and OS depth in normosmia is established.
• While group-level OB morphology is reliable, individual interpretations require caution due to variability and limited left-right shape agreement.