Lesion Detection at Ultrahigh Field

Objectives 7T MRI has demonstrated new aspects of the pathological features of multiple sclerosis (MS) using T2*-weighted sequences. However a clinical multicontrast MRI protocol at 7 T has not yet been investigated. We evaluated the clinical value of 7T-MRI by investigating sensitivity of lesion detection compared with 3 T. Methods 38 MS patients and 8 healthy controls underwent multicontrast MRI using 3D T1-weighted (3D-T1w), 2D dual-echo T2-weighted (2D-T2w) and fluid attenuated inversion recovery (3D-FLAIR) pulse sequences at 3 T and 7 T. Images were analysed for focal lesions which were counted and categorised according to anatomical location. The study was approved by the local 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 compared with 3 T. Patient-wise analysis confirmed this for 2D-T2w and FLAIR (P<0.023 and P<0.001). Lesion detection in white matter (WM) did not increase at 7 T; 3D-FLAIR even detected significantly more WM lesions at 3 T. Conclusions Using a clinical multicontrast MRI protocol, significantly increased lesion detection was observed in cortical GM but not in WM. Given the clinical relevance of GM abnormalities in MS, this may have substantial consequences for clinical outcome measures, prognostic classification and future diagnostic criteria incorporating GM abnormalities. 55 Multicontrast in vivo 7T vs 3T MRI in MS