Pathology-guided MR analysis of acute and chronic experimental allergic encephalomyelitis spinal cord lesions at 1.5T

Purpose: To directly correlate spinal cord pathology of guinea pigs with experimental allergic encephalomyelitis (EAE) to the MRI data obtained at 1.5T. Materials and Methods: Spinal cords from EAE animals were imaged in vivo with the following MRI sequences: T2-FSE, PD-FSE, fluid-attenuated inversion recovery (FLAIR)-FSE, T2-CSE, T1-CSE, T1-CSE + gadolinium-DTPA (Gd-DTPA), PD-CSE, and short-tau inversion recovery (STIR)-FSE. The spinal cords were removed and the lesions with specific pathological compositions were identified by histological anal- ysis. Regions of interest (ROIs) were drawn on the corresponding MR images, and signal-to-noise ratios (SNRs) were measured for each MR sequence and compared with controls. Results: The receiver operating characteristic (ROC) analysis of STIR-FSE and PD-CSE was able to differentiate tissue that contained cellular infiltrates with a high degree of accuracy. The SNRs of T2-FSE, STIR-FSE, T2-CSE, PD-CSE, and T1-CSE + Gd-DTPA were elevated in lesions that contained cellular infiltrates alone, whereas the SNRs of PD-CSE and T1-CSE + Gd-DTPA were reduced in demyelinated lesions that also contained inflammation. Conclusion: The SNR difference between the two lesion groups suggests that the combination of STIR-FSE, PD-CSE, and T1-CSE + Gd-DTPA sequences may be useful for differentiating inflammatory lesions containing demyelination from lesions with inflammation alone.