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Seven‐tesla phase imaging of acute multiple sclerosis lesions: A new window into the inflammatory process
Author(s) -
Absinta Martina,
Sati Pascal,
Gaitán María I.,
Maggi Pietro,
Cortese Irene C. M.,
Filippi Massimo,
Reich Daniel S.
Publication year - 2013
Publication title -
annals of neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.764
H-Index - 296
eISSN - 1531-8249
pISSN - 0364-5134
DOI - 10.1002/ana.23959
Subject(s) - multiple sclerosis , magnetic resonance imaging , medicine , lesion , pathological , pathology , phase imaging , gadolinium , in vivo , radiology , nuclear medicine , materials science , biology , microbiology and biotechnology , psychiatry , microscopy , metallurgy
Objective In multiple sclerosis (MS), accurate, in vivo characterization of dynamic inflammatory pathological changes occurring in newly forming lesions could have major implications for understanding disease pathogenesis and mechanisms of tissue destruction. Here, we investigated the potential of ultrahigh‐field magnetic resonance imaging (MRI; 7T), particularly phase imaging combined with dynamic contrast enhancement, to provide new insights in acute MS lesions. Methods Sixteen active MS patients were studied at 7T. Noncontrast, high‐resolution T2* magnitude and phase scans, T1 scans before/after gadolinium contrast injection, and dynamic contrast‐enhanced (DCE) T1 scans were acquired. T2*/phase features and DCE pattern were determined for acute and chronic lesions. When possible, 1‐year follow‐up 7T MRI was performed. Results Of 49 contrast‐enhancing lesions, 44 could be analyzed. Centrifugal DCE lesions appeared isointense or hypointense on phase images, whereas centripetal DCE lesions showed thin, hypointense phase rims that clearly colocalized with the initial site of contrast enhancement. This pattern generally disappeared once enhancement resolved. Conversely, in 43 chronic lesions also selected for the presence of hypointense phase rims, the findings were stable over time, and the rims were typically thicker and darker. These considerations suggest different underlying pathological processes in the 2 lesion types. Interpretation Ultrahigh‐field MRI and, especially, phase contrast, are highly sensitive to tissue changes in acute MS lesions, which differ from the patterns seen in chronic lesions. In acute lesions, the hypointense phase rim reflects the expanding inflammatory edge and may directly correspond to inflammatory byproducts and sequelae of blood–brain barrier opening. Ann Neurol 2013;74:669–678