Maturation of the Olfactory Bulbs: MR Imaging Findings

Abstract

BACKGROUND AND PURPOSE:The detection of time-related maturational changes of the olfactory bulb (OB) on MR imaging may help early identification of patients with abnormal OB development and anatomic-based odor-cueing anomalies.

Olfactory Bulb Signal Abnormality in Patients with COVID-19 Who Present with Neurologic Symptoms

“…The OB volume loss was a qualitative determination based on loss of the normal oval-or J-shaped morphology, or loss of volume compared with the contralateral OB. 15 The OB and olfactory tract signal intensity was assessed relative to the trigeminal nerve; OB and olfactory tract hyperintense to the trigeminal nerve was classified as abnormal. Quantitative assessment of the OB signal intensity was also performed.…”

“…10 The olfactory bulbs (OBs) are easily identified on conventional MR imaging and are located immediately beneath the olfactory sulci within the anterior cranial fossa, above the cribriform plate. The normal imaging appearance of the adult OB is well described [13][14][15] and should appear oval-or j-shaped in morphology and demonstrate uniform T2 signal intensity from the center to the periphery. 15 The olfactory neural network includes first-order projections to the piriform cortex and amygdala as well as secondary projections, including the orbitofrontal cortex, thalamus, and insula.…”

“…The normal imaging appearance of the adult OB is well described [13][14][15] and should appear oval-or j-shaped in morphology and demonstrate uniform T2 signal intensity from the center to the periphery. 15 The olfactory neural network includes first-order projections to the piriform cortex and amygdala as well as secondary projections, including the orbitofrontal cortex, thalamus, and insula. 16 Morphologic changes in the OB and associated areas have been shown in various other disease states, including chronic rhinosinusitis, post-viral anosmia, and neurodegenerative disease.…”

MR Imaging–Based Evaluations of Olfactory Bulb Atrophy in Patients with Olfactory Dysfunction

“…The boundaries of the OB were determined using the surrounding CSF and the anterior cribriform plate as markers. Atrophy of the OB was diagnosed on the basis of the following findings: flattening and thinning of the olfactory bulb with loss of the normal oval or J-shape of the OB, 17 and an asymmetric decrease in the size of the OB compared with the OB on the contralateral side (Fig 1). 18 Neuropathy was defined as neuromalacia of the OB, with focal or diffuse high signal intensity in the OB and increased signal compared with the signal intensity of the adjacent frontal white matter with/without decreased volume on 3D-FLAIR or coronal T2-weighted images (Fig 2).…”

Imaging of lamination patterns of the adult human olfactory bulb and tract: In vitro comparison of standard- and high-resolution 3T MRI, and MR microscopy at 9.4T

“…Multiple studies contradictorily interpreted this hyperintense structure as either bulbomalacia/neuromalacic bulb , atrophy or small dysontogenetic cysts (Abolmaali et al, 2008), central fluid compartment (Curtis et al, 2007), or OB ventricles (OBV) Smitka et al, 2009). The difficulty to assign this T2-hyperintensity to a specific anatomical structure or a pathologic or developmental condition is corroborated by the following fact: In 2009, Schneider et al (Schneider and Floemer, 2009) interpreted this T2-hyperintensity to be unmyelinated white matter that -undergoing a predefined and predictable maturational process -disappears at a median age of 5 years. This runs counter to the results of Smitka et al (2009) who showed similar T2-hyperintensities in adults (19-79 yrs.…”