TY - JOUR
T1 - The Shape of the Olfactory Bulb Predicts Olfactory Function
AU - Yan, Xiaoguang
AU - Joshi, Akshita
AU - Zang, Yunpeng
AU - Assunção, Francisca
AU - Fernandes, Henrique M.
AU - Hummel, Thomas
N1 - Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2022/2
Y1 - 2022/2
N2 - The olfactory bulb (OB) plays a key role in the processing of olfactory information. A large body of research has shown that OB volumes correlate with olfactory function, which provides diagnostic and prognostic information in olfactory dysfunction. Still, the potential value of the OB shape remains unclear. Based on our clinical experience we hypothesized that the shape of the OB predicts olfactory function, and that it is linked to olfactory loss, age, and gender. The aim of this study was to produce a classification of OB shape in the human brain, scalable to clinical and research applications. Results from patients with the five most frequent causes of olfactory dysfunction (n = 192) as well as age/gender-matched healthy controls (n = 77) were included. Olfactory function was examined in great detail using the extended “Sniffin’ Sticks” test. A high-resolution structural T2-weighted MRI scan was obtained for all. The planimetric contours (surface in mm2 ) of OB were delineated manually, and then all surfaces were added and multiplied to obtain the OB volume in mm3 . OB shapes were outlined manually and characterized on a selected slice through the posterior coronal plane tangential to the eyeballs. We looked at OB shapes in terms of convexity and defined two patterns/seven categories based on OB contours: convex (olive, circle, and plano-convex) and non-convex (banana, irregular, plane, and scattered). Categorization of OB shapes is possible with a substantial inter-rater agreement (Cohen’s Kappa = 0.73). Our results suggested that non-convex OB patterns were significantly more often observed in patients than in controls. OB shapes were correlated with olfactory function in the whole group, independent of age, gender, and OB volume. OB shapes seemed to change with age in healthy subjects. Importantly, the results indicated that OB shapes were associated with certain causes of olfactory disorders, i.e., an irregular OB shape was significantly more often observed in post-traumatic olfactory loss. Our study provides evidence that the shape of the OB can be used as a biomarker for olfactory dysfunction.
AB - The olfactory bulb (OB) plays a key role in the processing of olfactory information. A large body of research has shown that OB volumes correlate with olfactory function, which provides diagnostic and prognostic information in olfactory dysfunction. Still, the potential value of the OB shape remains unclear. Based on our clinical experience we hypothesized that the shape of the OB predicts olfactory function, and that it is linked to olfactory loss, age, and gender. The aim of this study was to produce a classification of OB shape in the human brain, scalable to clinical and research applications. Results from patients with the five most frequent causes of olfactory dysfunction (n = 192) as well as age/gender-matched healthy controls (n = 77) were included. Olfactory function was examined in great detail using the extended “Sniffin’ Sticks” test. A high-resolution structural T2-weighted MRI scan was obtained for all. The planimetric contours (surface in mm2 ) of OB were delineated manually, and then all surfaces were added and multiplied to obtain the OB volume in mm3 . OB shapes were outlined manually and characterized on a selected slice through the posterior coronal plane tangential to the eyeballs. We looked at OB shapes in terms of convexity and defined two patterns/seven categories based on OB contours: convex (olive, circle, and plano-convex) and non-convex (banana, irregular, plane, and scattered). Categorization of OB shapes is possible with a substantial inter-rater agreement (Cohen’s Kappa = 0.73). Our results suggested that non-convex OB patterns were significantly more often observed in patients than in controls. OB shapes were correlated with olfactory function in the whole group, independent of age, gender, and OB volume. OB shapes seemed to change with age in healthy subjects. Importantly, the results indicated that OB shapes were associated with certain causes of olfactory disorders, i.e., an irregular OB shape was significantly more often observed in post-traumatic olfactory loss. Our study provides evidence that the shape of the OB can be used as a biomarker for olfactory dysfunction.
KW - Anosmia
KW - Deformation
KW - MRI
KW - Olfaction
KW - Olfactory bulb shape
KW - Plasticity
KW - Smell
UR - http://www.scopus.com/inward/record.url?scp=85123189226&partnerID=8YFLogxK
U2 - 10.3390/brainsci12020128
DO - 10.3390/brainsci12020128
M3 - Journal article
C2 - 35203892
AN - SCOPUS:85123189226
SN - 2076-3425
VL - 12
JO - Brain sciences
JF - Brain sciences
IS - 2
M1 - 128
ER -