Korean J Radiol.  2019 Nov;20(11):1536-1545. 10.3348/kjr.2019.0104.

Altered Functional Brain Networks in Patients with Traumatic Anosmia: Resting-State Functional MRI Based on Graph Theoretical Analysis

Affiliations
  • 1Department of Radiology, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Korea. mdmoonwj@naver.com
  • 2Department of Radiology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
  • 3Laboratory for Cognitive Neuroscience and NeuroImaging, Department of Bio and Brain Engineering, and KI for Health Science and Technology, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, Korea. yong@kaist.ac.kr
  • 4Department of Otorhinolaryngology-Head and Neck Surgery, Konkuk University Medical Center, Konkuk University School of Medicine, Seoul, Korea.

Abstract


OBJECTIVE
Traumatic anosmia is a common disorder following head injury; however, little is known regarding its neural basis and influence on the functional networks. Therefore, we aimed to investigate the functional connectivity changes in patients with traumatic anosmia compared to healthy controls using resting-state functional magnetic resonance imaging (rs-fMRI).
MATERIALS AND METHODS
Sixteen patients with traumatic anosmia and 12 healthy controls underwent rs-fMRI. Differences in the connectivity of the olfactory and whole brain networks were compared between the two groups. Graph theoretical parameters, such as modularity and global efficiency of the whole brain or olfactory networks, were calculated and compared. Correlation analyses were performed between the parameters and disease severity.
RESULTS
Patients with traumatic anosmia showed decreased intra-network connectivity in the olfactory network (false discovery rate [FDR]-corrected p < 0.05) compared with that in healthy controls. Furthermore, the inter-network connectivity was increased in both the olfactory (FDR-corrected p < 0.05) and whole brain networks (degree-based statistic-corrected p < 0.05) in the anosmia group. The whole brain networks showed decreased modularity (p < 0.001) and increased global efficiency (p = 0.019) in patients with traumatic anosmia. The modularity and global efficiency were correlated with disease severity in patients with anosmia (p < 0.001 and p = 0.002, respectively).
CONCLUSION
Traumatic anosmia increased the inter-network connectivity observed with rs-fMRI in the olfactory and global brain functional networks. rs-fMRI parameters may serve as potential biomarkers for traumatic anosmia by revealing a more widespread functional damage than previously expected.

Keyword

Traumatic anosmia; Functional magnetic resonance imaging; Resting state; Brain networks; Functional connectivity; Graph theory
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