Results

3.1 Clinical characteristics

Considering the risk of exposure to COVID-19 in the hospital, the cost and time of data acquisition and spectroscopy, we included only seven healthy volunteers in the study as control group (4 males and 3 females; mean age: 27.28, range: 20-38; Ir-SIT mean score: 20.1). Seven patients (4 males and 3 females; mean age: 29.57 years. range: 18–41; Ir-SIT mean score:7.5) met the inclusion criteria in COVID-19 related anosmia. The Mean duration of anosmia before the imaging was 8.5 months in these patients. Demographic characteristics relating to participants are summarized in table 1.

3.2 MRS results

As illustrated in Figure 1A, the NAA level within OFC (p=0.001) and VMPFC (p=0.026) detected by MRS in patients with COVID-19 related anosmia was significantly lower than the control group. Interestingly, anosmic patients exhibited a lower NAA level than the control group in all ROI (Table 2).
As opposed to NAA, there was no significant difference between groups for Cho levels. Nonetheless, as represented in Figure 1B, a diffuse non-significant decrease of Cho level in anosmic patients compared to the control group was observed (Table 2).
As reflected in Figure 1C, there was a significant reduction of Cr level within OFC in anosmic patients comparing the control group (P=0.001) (Table 2).
NAA/Cho ratio within OFC was significantly different between groups (P=0.007) (Figure 1D) (Table 2).
We found no significant differences inNAA/Cr orCho/Cr ratios among the two groups (Figure 1E and Figure 1F) (Table 2).
Our results demonstrated a significant association between OFC neurometabolite impairment and COVID-19 related anosmia (Pdisease<0.001) (Figure 2). Repeated measured ANOVA analysis revealed that the interactions of NAA (Pinteraction=0.006) and Cr (Pinteraction=0.043) within OFC were significantly different between the two groups (Tables 2).
Gnuplot of Tarquin ex amples shown  in Figure 3 has provided a visual display of the distribution of brain neurometabolites of the OFC spectroscopy in each group.