Magnetic Resonance Neurography Visualizes Abnormalities in Sciatic and Tibial Nerves in Patients with Type 1 Diabetes and Neuropathy

This study evaluates whether diffusion-tensor-imaging MR-Neurography (DTI-MRN), T2-relaxation-time and proton-spin-density can detect and grade neuropathic abnormalities in patients with type 1 diabetes.Forty-nine patients with type 1 diabetes (11 with severe polyneuropathy (sDPN), 13 with mild polyneuropathy (mDPN) and 25 without polyneuropathy (nDPN)) and 30 healthy controls (HC) were included. Clinical examinations, nerve-conduction-studies and vibratory-perception-thresholds determined the presence and severity of DPN. DTI-MRN covered proximal (sciatic nerve) and distal (tibial nerve) nerve segments of the lower extremity. Fractional-anisotropy (FA) and the apparent-diffusion-coefficient (ADC) were calculated together with T2-relaxation-time and proton-spin-density obtained from DTI-MRN: All MR findings were related to presence and severity of neuropathy.FA of the sciatic and tibial nerve was lowest in the sDPN group. Correspondingly, proximal and distal ADC was highest in sDPN compared to patients with mDPN and nDPN as well as HC. DTI-MRN correlated closely with the severity of neuropathy demonstrating strong associations with sciatic and tibial nerve findings. Quantitative proton-spin-density group differences were also significant but less pronounced than for DTI-MRN.In conclusion, DTI-MRN enables detection of abnormalities in peripheral nerves related to DPN and more so than proton-spin-density or T2-relaxation-time. These abnormalities are likely to reflect pathology in sciatic and tibial nerve fibers.