The purpose of this study was to investigate the relationship between the volume of the olfactory bulb (OB), the depth of the olfactory sulcus (OS), the depth of the fossa olfactoria (FO), and the height of the OB.Methods
A total of 54 patients participated (9 women and 45 men; mean [SD] age, 27  y; range, 20–45 y). Magnetic resonance imaging was performed with a 1.5-T system (slice thickness, 1 mm). Measurements of the right and left OB volumes were performed through manual segmentation of the coronal slices. We measured the depth of the FO on the basis of Keros classification on coronal magnetic resonance images. The depth of the OS was measured on the coronal plane at the posterior tangent through the orbital globes. The height of the OB was measured on the coronal plane of the cribriform plate at the highest portion of the OB.Results
The mean (SD) right OB volume was measured to be 52.21 (13.73) mm3 with a range between 33.90 and 95.70 mm3. The mean (SD) left OB volume was measured to be 53.98 (13.31) mm3 with a range between 31.20 and 94.10 mm3. Type 1, type 2, and type 3 Keros ratios of the FO bilaterally were 12.9% (7/54), 68.5% (37/54), and 3.7% (2/54), respectively. There was no significant relationship between the OB volume and ipsilateral Keros type of FO (right side: P = 0.208; left side: P = 0.164). Similarly, there was no significant relationship between the OB volume and depth of OS on both sides (right side: P = 0.073; left side: P = 0.065). There was no significant association between the Keros type of the right FO and depth of the OS (right side: P = 0.812; left side P = 0.863).Conclusions
We conclude that there is no statistical correlation between the OB volume and depth of the FO (Keros type). From the current study, it may be concluded that the depth of the FO may develop largely independent from OB volumes. The individuals without smell disorder have a wide range in OB volume. The method of OB volume measurement that we described is a valid measure of real OB volumes with high reproducibility.