A Comparison of 3T and 7T in the Detection of Small Parenchymal Veins Within MS Lesions

Objective: Histologic examination of multiple sclerosis (MS) brain lesions reveals heterogeneity including the presence or absence of a central blood vessel. Recent work has shown that T-2* weighted magnetic resonance imaging at 7T allows the identification of small parenchymal veins within MS lesions. The aims of this study were (1) to compare whether a comparable sequence at 3T was also capable of demonstrating parenchymal veins within MS brain lesions, and (2) to investigate the potential of 7T T-2* weighted imaging to differentiate between MS white matter lesions and age-related vascular lesions seen in controls. Materials and Methods: Seven patients with demyelinating brain disease and 7 healthy volunteers were scanned at 3T and 7T. Fluid attenuated inversion recovery (FLAIR) images acquired at 3T were used to identify each brain lesion in each patient. A comparison of images from both field strengths was then made to determine whether white matter lesions seen in 3T FLAIR images could be identified in T-2*-weighted images, and whether a central vein could be detected. Results: A total of 358 brain lesions were identified in the brains of the 7 patients using 3T FLAIR images. The 3T T-2* sequence detected 89% of FLAIR lesions compared with 94% using the 7T T-2* sequence (P = 0.0002). A central vessel could be identified in 45% of visible lesions using 3T T-2* and 87% of visible lesions using 7T T-2* (P < 0.0001). Using 7T T-2* imaging a central vein was evident in only 8% of the discrete white matter lesions found in the brains of healthy volunteers. Discussion: This study suggests that ultra big h field imaging is advantageous in demonstrating detailed structural anatomy of MS lesions. 7T T-2* imaging can be used in the future to investigate the pathogenesis of MS lesions. The potential for ultra high field imaging to discriminate between MS white matter lesions and microangiopathic lesions warrants further investigation as this would represent a clinically useful application.