Abbreviations
- Magnetic resonance spectroscopy: MRS
- N-acetyl-aspartate: NAA
- Choline: Cho
- Creatine: Cr
- Anterior cingulate cortex: ACC
- Dorsolateral prefrontal cortex: DLPFC
- Orbitofrontal cortex: OFC
- Insular cortex: IC
- Ventromedial prefrontal cortex: VMPFC
- central nervous system: CNS
- region of interest: ROI
- Iran smell identification test: Ir-SIT
- Volume of interest: VOI
- single-voxel spectroscopy: SVS
Abstract
Objectives: COVID-19 infection is commonly associated with
olfactory dysfunctions, but the basic pathogenesis of these
complications remains controversial. This study seeks to evaluate the
value of magnetic resonance spectroscopy (MRS) in determining the
molecular neurometabolite alterations within the main brain olfactory
areas in patients with COVID-19 related anosmia.
Methods: In a cross-sectional study, seven patients with
persistent COVID19 related anosmia (mean age: 29.57 years) and seven
healthy volunteers (mean age: 27.28 years) underwent MRS in which
N-acetyl-aspartate (NAA), choline (Cho), creatine (Cr) and their ratios
were measured in the anterior cingulate cortex (ACC), dorsolateral
prefrontal cortex (DLPFC), orbitofrontal cortex (OFC), insular cortex
(IC) and ventromedial prefrontal cortex (VMPFC). Data were analyzed
using TARQUIN software (version 4.3.10), and the results were compared
with an independent sample T test and non-parametric Mann-Whitney test
based on the normality of the MRS data distribution.
Results: The mean duration of anosmia before imaging was 8.5
months. MRS analysis elucidated a significant association between MRS
findings within OFC and COVID-19 related anosmia
(Pdisease<0.01), and NAA was among the most
important neurometabolites (Pinteraction=0.006). Reduced
levels of NAA (P<0.001), Cr (P<0.001) andNAA/Cho ratio (p=0.007) within OFC
characterize COVID-19 related anosmia.
Conclusions: This study emphasizes that MRS can be illuminating
in COVID-19 related anosmia and indicates a possible association between
central nervous system impairment and persistent COVID-19 related
anosmia.
Key Points
- Magnetic resonance spectroscopy provides valuable data to identify the
basic pathogenesis of various central nervous system disorders such as
COVID-19.
- Orbitofrontal Cortex neurochemical dysfunction is significantly
associated with persistent COVID-19 induced anosmia.
- N-acetyl-aspartate within the orbitofrontal cortex was significantly
lower in patients with persistent COVID-19 related anosmia comparing
normal volunteer participants (P<0.001).
- According to the results, NAA was among the most
important neurometabolites (Pinteraction=0.006).
- The main findings of this study could shed light on future studies to
find more specific pharmacologic or nonpharmacologic treatments based
on MRS findings.