Multiparametric Quantitative MRI of Peripheral Nerves to Differentiate Demyelinating From Axonal Polyneuropathies

Area of Science:

• Neurology
• Radiology
• Biomarkers

Background:

• Accurate diagnosis of demyelinating versus axonal polyneuropathies is crucial for effective treatment.
• Current clinical tools have limitations in detecting demyelination in peripheral nerves, especially proximal ones.

Purpose of the Study:

• To evaluate the efficacy of multiparametric quantitative MRI (qMRI) in differentiating demyelinating from axonal polyneuropathies.
• To develop and validate a composite qMRI score (CMT Imaging Score - CMTIS) for disease severity assessment.

Main Methods:

• Retrospective study involving patients with Charcot-Marie-Tooth type-1 (CMT1), CMT2, hereditary neuropathy with liability to pressure palsies (HNPP), and healthy controls (HC).
• Utilized 3T MRI with 3D gradient-echo and spin-echo echo-planar-imaging-based diffusion tensor imaging.
• Computed various qMRI parameters including MTR, MTsat, T2*, T1, PD, FA, MD, AD, RD, and fascicular volume (fVol).
• Performed descriptive statistics, ROC analysis with logistic regression, and developed the CMTIS correlated with CMTNSv2.

Main Results:

• Distinct qMRI signatures were identified for CMT1 (increased fVol) and CMT2 (reduced T2*).
• Both CMT1 and CMT2 showed reduced FA, MTsat, and AD, with elevated T1 and RD compared to HCs, exhibiting greater abnormalities in CMT1.
• ROC analysis demonstrated strong discrimination between CMT1 and CMT2 for both sciatic and tibial nerves.
• The developed CMTIS showed a strong correlation with the clinical CMTNSv2 score.

Conclusions:

• Multiparametric qMRI successfully differentiates inherited demyelinating (CMT1) and axonal (CMT2) polyneuropathies based on unique imaging characteristics.
• The CMTIS demonstrates significant potential as a reliable biomarker for monitoring disease progression in patients with inherited polyneuropathies.