Objective: To investigate the brain volume alterations in patients with hyposmia using voxel-based morphometry (VBM) and to correlate these alterations with the degree and duration of hyposmia. Methods: Forty patients with hyposmia from Department of Otorhinolaryngology Head and Neck Surgery, Beijing Anzhen Hospital since 2013 to 2016 and forty age and sex matched normal subjects were recruited in this study. Sniffin′ Sticks olfactory test was performed to evaluate the olfactory function of all subjects. We acquired T1-weighted magnetic resonance images from all subject on a 3T scanner. VBM was performed using VBM8 toolbox and SPM8 in a Matlab environment. Independent sample t test analysis was used to compare the volume of gray and white matter between the controls and patients. In addition, the Pearson or Spearman correlation analysis was used for the correlation between the voxel value of cerebral volume alterations area and the degree and duration of hyposmia on patients (threshold discrimination identification, TDI). Results: Compared with the controls, patients showed significantly decreased volume in the gray matter of right orbitofrontal cortex (number of voxel in clusters was 226, t=-4.46, P<0.001, uncorrected). There was negative correlation between decreased gray matter volume of the right orbitofrontal cortex with significantly decreased area and the TDI results (r=-0.40, P=0.01), but positive correlation with duration of hyposmia (r=0.37, P=0.02). Conclusions The patients with hyposmia show gray matter atrophy of the right orbitofrontal cortex. The duration may be an important risk factor for decreased gray matter in patients with hyposmia.

Objective: To investigate the white matter integrity in patients with olfactory dysfunction using diffusion tensor imaging (DTI). Methods: Twenty-one patients with olfactory dysfunction and sixteen age, sex and level of education matched normal subjects were recruited in this study. Sniffin′ Sticks olfactory test was performed to evaluate the olfactory function of all subjects. We acquired diffusion tensor images with a echo planar imaging (EPI) sequence from all subjects on a 3T scanner. The fractional anisotropy (FA) images were performed using DTI-studio, and bilateral piriform cortex, orbitofrontal cortex, hippocampus and insula cortex adjacent white matter as well as capsula interna were delineated from the FA images as the region of interest associated with olfactory (ROI_awo) manually. Independent sample t test analysis was used to compare the FA value of all ROI_awo between the controls and patients. Results: In olfactory dysfunction group, the FA value of adjacent white matter of right piriform cortex and orbitofrontal cortex were significantly lower than those of control group (0.42±0.05 (±s) vs 0.45±0.05, 0.43±0.06 vs 0.49±0.07, t value was 2.32, 2.79, respectively, all P<0.05). The FA value of adjacent white matter of left piriform cortex and orbitofrontal cortex had no significant difference compared with those of control group (0.43±0.05 vs 0.45±0.04, 0.44±0.04 vs 0.47±0.06, t value was 1.65, 1.37, respectively, all P>0.05). The FA value of the adjacent white matter of bilateral hippocampus, insula cortex and capsula interna had no significant difference compared with those of control group, neither (0.45±0.08 vs 0.44±0.08, 0.45±0.09 vs 0.44±0.10, 0.41±0.08 vs 0.39±0.07, 0.41±0.07 vs 0.38±0.05, 0.64±0.08 vs 0.63±0.08, 0.64±0.07 vs 0.63±0.07, t value was 0.30, 0.15, 0.88, 1.34, 0.14, 0.35, respectively, all P>0.05). Conclusions The patients with olfactory dysfunction showed abnormal white matter connection in the major primary and secondary olfactory cortex. The reduced white matter integrity in ROI_awo might contribute to the pathogenesis of olfactory dysfunction.

Objective: Using ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) and microPET-CT to test the feasibility of ¹⁸F-FDG PET-CT for validation of olfactory function of rats with standard phenethyl alcohol (PEA) and isovaleric acid (IVA) odors stimulation. To verify the possibility of ¹⁸F-FDG PET-CT as a new objective examination method for olfactory function. Methods: Six healthy Sprague-Dawley (SD) male rats were selected with a weight of 250-300 g. First of all, buried food pellet test (BFT) was used to confirm the normal olfactory function of rats. Then in the next 3 days, after the intravenous injection of ¹⁸F-FDG (18 MBq/100 g), awaken rats were placed in a ventilated plexiglas cage for 30 min. Subsequently, pure air (the first day), PEA (the second day) and IVA (the third day) were delivered. After odor stimulation for 30 min, rats were performed by a static PET-CT under anesthesia. Images reconstructed were assessed by SPM method and analyzed by VBM method. Data was analysied by paired t test. Results: Activation regions of rat′s brain after PEA stimulation included bed nucleus and insula. Activation regions of rat′s brain after IVA stimulation included olfactory bulb, anterior olfactory nucleus, amygdala, entorhinal cortex, olfactory cortex, piriform cortex, insula, prefrontal cortex, cingulate cortex and bed nucleus (P<0.005, Ke>20 voxels). Conclusions Through microPET-CT, we can observe that olfactory stimulation with different odors can induce metabolic activation in different regions of rat′s brain, which was in concordance with olfactory regions. The olfactory related brain regions of rats have strong responses to odor stimulation of IVA.

Objective: To explore the clinical effects and the influence factors of olfactory training in the treatment of olfactory dysfunction. Methods: A total of 86 patients with olfactory dysfunction (49 post-infectious and 37 post-traumatic) in Beijing Anzhen Hospital during Dec 2016 to May 2017 were recruited in this prospective study. The clinical data of patients were analyzed, including gender, age, body mass index (BMI), course of disease, smoking history, drinking history, diabetes history, hypertension history, hyperlipidemia history, and anxiety visual analogue score (VAS). All patients were treated with olfactory training for 16 weeks, and all of them underwent Sniffin′ Sticks olfactory test before and after treatment, which was evaluated by composite threshold-discrimination-identification score (TDI). SPSS 23.0 software, paired t test and univariate and multivariate Logistic regression analysis were used to analyze the data. Results: Eighty patients received treatment, including 46 post-infectious olfactory dysfunction and 34 post-traumatic olfactory dysfunction. After olfactory training, the total scores of TDI increased with statistically significant (18.3±8.6 vs 13.6±7.4, t=-6.158, P<0.05). The overall efficacy was 40% (32/80). The effective rate were 45.7% (21/46) in post-infectious olfactory dysfunction and 32.4% (11/34) in post-traumatic olfactory dysfunction respectively, with no statistically significant difference (χ²=1.441, P=0.230). Logistic regression analysis showed that the course of disease was an influence factor in the clinical curative effect (OR=0.881, 95%CI: 0.799-0.973, P=0.012). In patients with less than a year of olfactory dysfunction, the olfactory function improved obviously with the efficiency of 50.9% (29/57). Conclusion Sixteen weeks of olfactory training provides a significant therapeutic effect on the post-infectious and post-traumatic olfactory dysfunction, and the olfactory training can achieve better therapeutic effects at the early stage.