Standardized, reproducible, high resolution global measurements of T1 relaxation metrics in cases of multiple sclerosis.

BACKGROUND AND PURPOSE We herein present a methodology for standardized and clinically applicable measurement of T1 relaxation maps with high resolution and volumetric coverage by using the commercially available 3D spoiled gradient-echo sequence. The reproducibility of the T1 metrics derived from these maps and their sensitivity to distinguish between control participants and patients with multiple sclerosis are evaluated. METHODS Axial view 3D RF spoiled data sets with two flip angles were acquired at 1.5 T to generate the T1 maps, with all other imaging parameters (27/6 ms [TR/TE]; field of view, 180 x 240 x 186 mm(3); matrix, 192 x 256 x 124) kept identical between the two acquisitions. T1 maps were collected from 20 normal control participants and 32 patients with multiple sclerosis. An automated and operator-independent method was developed to segment the relaxation maps and define T1 metrics. RESULTS We showed that the metrics derived from these maps to represent tissue characteristics were highly reproducible (coefficient of variation, approximately 1% to 4%) and were significantly different between normal control participants and patients with multiple sclerosis (P <.001) for the small cohort of patients in this study. CONCLUSION The commercially accessible 3D spoiled gradient-echo sequence can be used to generate T1 relaxation maps with high resolution and volumetric coverage. The metrics derived from the relaxation maps are reproducible and have been shown to be sensitive to qualitative and quantitative differences between subgroups of patients with multiple sclerosis and control participants, with strong statistical significance. The use of a commercially available sequence enables the standardization and comparison of T1 metrics across different multiple sclerosis centers.