[Volumetry of the olfactory bulb - One component in the objectification of disorders of the sense of smell].

Disorders of olfaction are a frequent reason for an assessment in otorhinolaryngology. Particularly when the results of subjective and/or objective olfactometry are inconclusive, additional objective findings are required to verify disorders of the sense of smell. Based on practical experience and considering the current literature, this article is intended as an aid in the preparation of supplementary radiological reports. The importance of comprehensive up to date standard imaging including olfactory bulb volumetry in addition to a detailed medical history and, if applicable, previous findings should be emphasized. In addition to the documentation of alterations in the anatomical structures involved in olfaction, which support the reported disorders in the sense of smell, special neuroradiological examination sequences for the visualization of the olfactory bulb, including a volumetric measurement of the same, can provide an objective component for the assessment of sometimes only subjectively existing disorders of the sense of smell. In the majority of cases no valid comparative volumetry can be derived from a possibly pre-existing imaging study. Therefore, a comparison with olfactory bulb reference values, determined in studies for the presumed etiology and the extent of the disorder reported/determined by olfactometry is the only way to put the olfactory bulb volume in an almost objective relationship to the function of the sense of smell reported and/or determined by olfactometry.