Prognostic Value of Brain Tissue Pathological Changes in Patients with Multiple Sclerosis Using Magnetization Transfer Parameters

The aim of this study is to investigate abnormalities and characterize pathologic changes associated with demyelination in the brain tissue of patients with multiple sclerosis (MS). In this method, magnetization transfer parameters such as magnetization transfer ratio (MTR), magnetization transfer rate (Ksat) and native relaxation time of brain tissue with and without applying saturation pulse were determined (Tlfree , Tlsat). Measurements were performed with segmentation regional measurements and histogram analysis. It had been shown that individual valuables contributing to magnetization transfer process can be provide further insight into the mechanisms of myeline destruction in multiple sclerosis disease. Conventional MR imaging protocols such as T1-weighted, T2-weighted, T2-FLAIR as well as MT-3DSPGR images were performed on five MS patients and five normal subjects. White matter and lesion masks were segmented from T2-weighted images and superimposed on MT parameter maps using FSL software. MTI parameters of lesions and normal appearing white matter (NAWM) were analyzed in comparison with those of normal volunteers. The MTR histograms of white matter were also generated for patient and normal subjects. A significant reduction was found in mean MTR and Ksat parameters with an increase of T1free and T1sat values in patient white matters and lesions in comparison with normal controls. A significant reduction was found in white matter MTR histogram height and position accompanied with a total shift to the left between MS patients and healthy subjects. Significant reduction in NAWM-MTI parameters of MS patients compared to normal subjects, shows that pathological changes occur outside visible lesions on conventional MR images among patients with multiple sclerosis. Quantitative MT imaging can help to evaluate the extent of global damage in the brain tissue.