Clinical application of multi-contrast 7-T MR imaging in multiple sclerosis: increased lesion detection compared to 3 T confined to grey matter.

OBJECTIVES: Seven-Tesla MRI demonstrated new pathological features of multiple sclerosis (MS) using T2-weighted sequences. However, a clinical MRI protocol at 7 T has never been investigated. We evaluated the clinical value of 7-T MRI by investigating the sensitivity of lesion detection compared with 3 T.
METHODS: Thirty-eight MS patients and eight healthy controls underwent multi-contrast MRI using 3D T1-weighted (3D-T1w), 2D dual-echo T2-weighted (2D-T2w) and 3D fluid-attenuated inversion recovery (3D-FLAIR) at 3 and 7 T. Images were analysed for focal lesions, which were counted and categorised according to anatomical location. The study was approved by the institutional review board.
RESULTS: Lesion-wise analysis showed increased lesion counts in cortical grey matter (GM) at 7 T of 91, 75 and 238 % for 3D-T1w, 2D-T2w and FLAIR sequences, respectively. Patient-wise analysis confirmed this for 2D-T2w and FLAIR (P < 0.023 and P < 0.001). Seven-Tesla white matter (WM) lesion detection was not increased; 3D-FLAIR even detected significantly more WM lesions at 3 T.
CONCLUSIONS: Using a clinical multi-contrast MRI protocol, increased lesion detection was observed in cortical GM but not in WM. Given the clinical relevance of GM abnormalities, this may have consequences for clinical outcome measures, prognostic classification and future diagnostic criteria incorporating GM abnormalities.