Background: Contrast of conventional MRI images is influenced by different parameters such as T1, T2, and proton density that may lead to invisibility and undetectibility of some small lesions in the normal appearing white matter (NAWM) in patients with multiple sclerosis (MS). Each brain tissue has specific values for T1 and T2 that usually changes in different pathologic lesions, thus, these differences may help clinician to differentiate different pathologies by measurement of these relaxation times. The present study was conducted to determine the association between the multiple sclerosis and relaxation time of MR in brain tissue.

Materials and methods : For this case-control study, 15 patients with MS and 15 normal subjects were selected. MRI was performed in Imam hospital on 1.5 Tesla   Picker MRI system. First, T1 and T2 maps were computed from two images using spin echo (SE) and inversion recovery (IR) pulse sequences with optimization of interpulse time intervals TE, and TR to minimize errors. Then, T1 and T2 values of brain tissues were measured.

Results : Results have revealed that not only T1 and T2 values in MS plaques increase significantly (P<0.0077), but also these values in NAWM increase accordingly T1 of NAWM changes between 2.99% and 10.23% (p<0.01) and T2 changes between 5.06% and 16.21% (p<0.037), whereas T2 in normal appearing gray matter (NAGM) decrease to a value between 2.07% and 5.07%, p<0.038).

Conclusion : Increasing of T1 and T2 in NAWM and decreasing of T2 value in NAGM can be considered as a fdiagnostic parameter of MS diseases.