Reproducibility and reliability of volumetric measurements of olfactory eloquent structures

Rationale and Objectives. The authors assessed the reliability and reproducibility of volumetric measurements of olfactory bulbs and tracts (OBTs) and temporal lobes (TLs) with magnetic resonance (MR) imaging. Methods. Repetitive MR imaging of two phantoms and OBTs and TLs of patients was performed. Regions of interest were manually drawn around the relevant structures, and their volumes were measured at workstations. Intra- and interobserver variability for the two readers were measured. Intraclass and Pearson correlation coefficients and mean percentage differences were calculated. Results. The measured phantom volumes were within 1.9%-12% of the true volumes with a variability of 15%. Intraclass and Pearson correlation coefficients were greater than or equal to 0.919 for measurements by a single reader and greater than or equal to 0.924 for measurements by different readers. The inter- and intraobserver variabilities were less than or equal to 4.2% for TL and 11.3%-14.6% for OBTs. Conclusion. Volumetric measurements of the olfactory apparatus can be reliably and accurately reproduced from MR images.