Quantitative MRI (qMRI) methods were developed to measure T1, T2, proton density, and MTR of mouse sciatic nerve in-vivo. Pmp22+/- mouse, an animal model of hereditary neuropathy with liability to pressure palsies (HNPP), was imaged at 3- and 6-month of age. The imaging demonstrated an increase of MTR, and a decrease of proton density and T1 in the Pmp22+/- nerves, compared with those in wild-type nerves. These qMRI changes correlate with the growth of HNPP pathology – tomacula formed by excessive myelin folding over time. Ongoing experiment is to determine the pathological and molecular substrates responsible for the qMRI findings.