In vivo quantitative whole-brain T₁ rho MRI of multiple sclerosis

Background To apply quantitative whole-brain T₁-rho (T_1ρ) and T₂ imaging to the detection and quantification of brain changes resulting from multiple sclerosis (MS). Methods Twenty-three MS patients with clinically isolated syndrome (10) and relapsing remitting MS (13) phenotypes, compared with 24 age-matched healthy controls were imaged at 3 Tesla. An axial T_1ρ-weighted three-dimensional turbo spin echo sequence with a variable flip angle and fluid suppression was used. Spin-lock times of 0, 20, 40, 60, 80, and 100 ms were used. Corresponding T₂ maps were also acquired. Results Whole brain white matter (WM) T_1ρ maps were elevated compared with controls (P = 0.002). WM lesion T_1ρ and T₂ values were highly correlated (r = 0.83), but T_1ρ demonstrated 25% better contrast to noise ratio (P < 0.001). WM lesion T_1ρ correlated with disease duration. Gray matter T_1ρ was negatively correlated with the Expanded Disability Status Scale, r = -0.45, P = 0.03. Normal appearing gray matter and cortical gray matter lesions were negatively correlated on T_1ρ, but not on T₂ (r_T1ρ = -0.63, p_T1ρ = 0.03; r_T2 = -0.17, p_T2 = 0.6). Conclusion T_1ρ MRI demonstrates enhanced lesion contrast compared with T₂, and in some cases may provide complementary information. T_1ρ may provide a useful measure of demyelinating processes in MS.