Magnetic Resonance T2-relaxation Time as an Indirect Measure of Brain Water Content and Disease Activity in Neuromyelitis Optica Spectrum Disorders - European Medical Journal
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Magnetic Resonance T2-relaxation Time as an Indirect Measure of Brain Water Content and Disease Activity in Neuromyelitis Optica Spectrum Disorders

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2 Mins
EMJ Neurology 9.1 2021 Feature Image
Authors:
Laura Cacciaguerra,1,2,3 Maria A. Rocca,1,2,3 Elisabetta Pagani,1 Marta Radaelli,2 Sarlota Mesaros,4 Vittorio Martinelli,2 Jovana Ivanović,4 *Massimo Filippi1-3,5,6
Disclosure:

The authors have declared no conflicts of interest.

Acknowledgements:

The authors would like to thank Associazione Amici del Centro Dino Ferrari for its support.

Support:

This study was supported by the Fondazione Italiana Sclerosi Multipla with a senior research fellowship (FISM2019/BS/009), a research grant from (FISM2018/R/16), and financed or co-financed with the ‘5 per mille’ public funding.

Citation
EMJ Neurol. ;9[1]:44-45. Abstract Review No. AR5.

Each article is made available under the terms of the Creative Commons Attribution-Non Commercial 4.0 License.

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BACKGROUND AND AIMS

Neuromyelitis optica spectrum disorders (NMOSD) are a group of conditions affecting the central nervous system.1 Most patients present a seral antibody targeting the aquaporin-4 channel on astrocytes, at the blood–brain barrier interface.1 During relapses, it is possible to observe radiological signs suggesting increased water permeability, such as the presence of bright spotty lesions and posterior reversible encephalopathy syndrome.2.3 However, at state of the art, no biomarkers to predict relapses and monitor the disease course are available.4 Following the hypothesis that, in NMOSD, astrocytes damage could determine subclinical brain water accumulation, possibly varying according to disease activity (relapses), this work aimed to estimate brain water content indirectly by measuring T2-relaxation time (T2rt) in NMOSD patients. The authors also assessed whether T2rt differs in patients having a short-term relapse.

MATERIALS AND METHODS

The authors recruited 77 aquaporin-4-positive patients with NMOSD and 84 age-matched healthy controls (HC) from two European centres (Milan, Italy, and Belgrade, Serbia), undergoing a standardised MRI protocol. The clinical evaluation included the assessment of the Expanded Disability Status Scale (EDSS).5 The authors also annotated the time from the last and subsequent relapse with respect to the date of MRI acquisition.

The T2rt was calculated from brain dual-echo turbo spin-echo images assuming a monoexponential decay to obtain T2rt maps of the normal-appearing white matter (NAWM), grey matter (GM), and basal ganglia. Short-term relapses were defined as occurring within one month before or after MRI scan. Differences between the patients with NMOSD and the HC were assessed with age-, sex-, and site-adjusted linear models. Receiver operating characteristic analyses were run to identify discriminators between stable and short-term relapsing patients.

RESULTS

HC and patients were comparable in age (mean age 41 versus 44 years, respectively), whereas the female to male ratio was higher in patients than HC (62/15 versus 50/34; p=0.004). Compared to HC, patients had significant atrophy of the brain (1482 ml versus 1582 ml; p<0.001), white matter (747 ml versus 780 ml; p=0.007), and GM (732 ml versus 803 ml; p<0.001). In addition, patients with NMOSD had increased T2rt in the GM (103 ms versus 97 ms; p<0.001), NAWM (88 ms versus 84 ms; p<0.001), and putamen (75 ms versus 72 ms; p<0.001) compared to HC. Short-term relapses occurred in 20/77 (26%) of patients. At receiver operating characteristic analysis, higher values of T2rt in the NAWM were able to discriminate between short-term relapsing and stable patients with good accuracy (area under the curve: 0.70; p=0.027).

CONCLUSION

Patients with NMOSD had increased T2rt values, suggesting a subclinical water accumulation in this disorder. The burden of T2rt alterations might be a helpful index of disease activity.

References
Wingerchuk DM et al. International consensus diagnostic criteria for neuromyelitis optica spectrum disorders. Neurology. 2015;85(2):177-89. Yonezu T et al. "Bright spotty lesions" on spinal magnetic resonance imaging differentiate neuromyelitis optica from multiple sclerosis. Mult Scler. 2014;20(3):331-7. Magaña SM et al. Posterior reversible encephalopathy syndrome in neuromyelitis optica spectrum disorders. Neurology. 2009;72(8):712-7. Rocca MA et al. Moving beyond anti-aquaporin-4 antibodies: emerging biomarkers in the spectrum of neuromyelitis optica. Expert Rev Neurother. 2020;20(6):601-18. Kurtzke JF. Rating neurologic impairment in multiple sclerosis: an expanded disability status scale (EDSS). Neurology. 1983;33(11):1444-52.