Quantitative MRI assessment of peripheral nerve injury in ATTRv amyloidosis patients

<p>Background and Objectives: Early detection of peripheral nerve damage in patients with hereditary transthyretin amyloidosis (ATTRv) has become essential for the prompt initiation of effective therapies that have been recently approved. In our study, we propose a new variable echo time (vTE) MRI sequence for aiding in the quantitative assessment of nerve damage. The approach allows the detection of signals from short T2 components of the nerve, such as the epineurium, myelin, and possibly pre-fibrillar amyloid material deposition within the nerve.</p> <p>Methods: In this cohort study, twenty patients with clinically confirmed ATTRv polyneuropathy (PNP) and twenty-one healthy controls (HC) underwent 3T MRI. vTE was performed on the right thigh with a 6 cm longitudinal coverage of the sciatic nerve between the gluteal region and the popliteal fossa. From the vTE acquisition, cross-sectional area (CSA) of epineurium and fascicular regions were calculated manually and the corresponding pseudoT2* (pT2*), a parameter related to the intrinsic T2 relaxation time of a given tissue, was extrapolated from the two acquired echoes of the vTE.</p> <p>Results: Significantly higher CSA, fascicular area, and pT2* were found in the ATTRv group compared to healthy controls. pT2* also correlated with previously validated clinical outcome measures (i.e., Polyneuropathy Disability Scoring System, Neuropathy Impairment Score (NIS), and NIS items related to lower limbs), and with nerve conduction parameters, demonstrating the ability to discriminate ATTRv patients with different degrees of PNP from HC.</p> <p>Conclusion: In conclusion, the vTE sequence provides novel and reliable imaging markers capable of detecting early nerve microstructural changes that relate to disease onset and severity.</p>