Double pulsed-field gradient (d-PFG) MRI has recently been suggested as an additional methodology for studying microstructure in the CNS^1-3. Previously we had studied the CNS of the Long Evans shaker (les) rats using q-space diffusion MRI (QSI)^4,5. More recently we have been interested in using the angular d-PFG MRI to study microstructural changes that occur in the spinal cords of the les rats, which are considered a model of dysmyelination. Here, the d-PFG MRI data was fitted to a model from which the unique parameter L/R ratio and its fractions were extracted. MRI experiments were conducted on a Bruker Avance-III 14.1T scanner, capable of producing pulsed field gradients of up to 300 G/cm in each direction. Fixed ex-vivo control and les rat spinal cords of 33 days of age were immersed in PBS overnight and then placed in 5 mm glass tubes filled with Fluorinert, to assure fiber orientation along the z-direction. The d-PFG MRI experiments were conducted with a finite mixing time (t_m) of 12 ms, on five controls and les spinal cords. G₁ was fixed in the x-direction and the orientation of G₂ was varied in the x-z plane (d-PFG_xz) using 13 different values of φ between 0^o and 360^o. The measurements were conducted using a d-PFG MRI sequence with EPI readout³ and with the following parameters: slice thickness of 800 µm, field of view (FOV) of 4.8x4.8 mm², in-plane spatial resolution of 50x50 µm², 2 segments, TR/TE=3200/52 ms, δ₁=δ₂=1 ms, Δ₁=Δ₂=15 ms and 120 averages (total acquisition time of ~3 hours). As required for the MCF analysis, each of the experiments were performed with 5 q-values (824-1030 cm^-1) in addition to a q=0 experiment. A multiple correlation function (MCF) analysis was performed using an in-house Matlab code for six chosen ROIs in both the white matter (WM) and gray matter (GM).Figure 1 presents the six ROIs on a clustered d-PFG MRI image of a control spinal cord (t_m=12 ms). These include three white matter (WM) ROIs; WM₁, WM₂ and WM₃ and three gray matter (GM) ROIs; GM₁, GM₂ and GM₃. Figure 2 shows E(φ) profiles and their fitting for four of the six ROIs in representative 33 days old control and les rats. Clearly, the data as well as its fitting appear to be robust, showing modulations of increased depths beginning from GM₁ up to WM₃. In both the control and les spinal cords, the modulations are most pronounced in the WM ROIs, as expected, due to the organized cylindrical like anisotropic microstructure. The GM ROIs show less pronounced modulations which are suggestive of the presence of less anisotropic microstructure. Note that the les spinal cord shows a more shallow modulation in most ROIs observed. This is expected due to their dysmyelination and less organized microstructure. Each of the six ROIs in the controls and les spinal cords was analyzed by the MCF, which provided the L/R ratios and their fractions, as shown in Figure 3. Note that the L/R distribution is wide and covers most values in both the control and les although the L/R fractions are much smaller in the les. This implies that the les spinal cords do comprise of some highly anisotropic microstructures (mainly in the WM ROIs) similar to the controls, although with much smaller fractions.The MCF analysis is capable of fitting the data from angular d-PFG_xz MRI experiments performed on controls and les rat spinal cords. The unique parameter, L/R ratio, is extracted together with its fraction. The angular d-PFG_xz MRI experiments, analyzed by the MCF paradigm are capable of distinguishing between the control and les rat spinal cords.