MRI detects peripheral nerve and adjacent muscle pathology in non-systemic vasculitic neuropathy (NSVN)
Diagnosis and disease monitoring of non-systemic vasculitic neuropathy (NSVN) are based on electrophysiological and clinical measures. However, these methods are insensitive to detect subtle differences of axonal injury. We here assessed the utility of a multiparametric MRI protocol to quantify axonal injury and neurogenic muscle damage in NSVN.
Ten NSVN patients and ten age-matched controls were investigated in this single-center prospective study. All participants were assessed by diffusion tensor imaging (DTI) of the tibial nerve and multiecho Dixon MRI of soleus and gastrocnemius muscles. These data were correlated with clinical and electrophysiological data.
DTI scans of the tibial nerves of patients with NSVN showed significantly lower mean fractional anisotropy (FA) values (0.32 ± 0.02) compared to healthy controls (0.42 ± 0.01). FA values of NSVN patients correlated negatively with clinical measures of pain. Multiecho Dixon MRI scans revealed significantly higher intramuscular fat fractions in the soleus muscle (19.86 ± 6.18% vs. 5.86 ± 0.74%, p = 0.0015) and gastrocnemius muscle (26.09 ± 6.21% vs. 3.59 ± 0.82%, p = 0.0002) in NSVN patients compared to healthy controls.
Our data provide a proof of concept that MRI can render information about nerve integrity and muscle pathology in NSVN. Further studies are warranted to evaluate DTI and multiecho Dixon MRI as surrogate markers in NSVN.
KeywordsNon-systemic vasculitic neuropathy DTI Proton-density fat fraction Polyneuropathy Neuromuscular disease
We thank Jan Borggrefe for support in statistical analysis of interrater agreement and Claudia Müller for technical assistance.
CS: study concept, conducting the study, data interpretation, drafting the manuscript. AS: study concept, conducting the study, analysis of data, drafting the manuscript. KW: study concept, technical assistance. KS: analysis of data. DM: study concept, drafting the manuscript for content. GRF: study concept, drafting the manuscript for content. TH: study concept. HCL: study concept, drafting the manuscript for content. TL: study concept, data analysis, drafting the manuscript.
Compliance with ethical standards
Conflicts of interest
KW is an employee of Philips Healthcare Germany since 10/2014. He reports personal fees from Philips Healthcare Germany, during the conduct of the study and personal fees from Philips Healthcare Germany, outside the submitted work. The other authors state that there is no conflict of interest.
All procedures involving human participants were in accordance with the ethical standards of the institutional research committee and the ethical standards laid down in the 1964 Declaration of Helsinki and its later amendments.
Informed consent was obtained from all the individual participants included in the study.
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