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Multicenter Study
, 25 (3), 352-360

Impact of 3 Tesla MRI on Interobserver Agreement in Clinically Isolated Syndrome: A MAGNIMS Multicentre Study

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Multicenter Study

Impact of 3 Tesla MRI on Interobserver Agreement in Clinically Isolated Syndrome: A MAGNIMS Multicentre Study

Marloes Hj Hagens et al. Mult Scler.

Abstract

Background: Compared to 1.5 T, 3 T magnetic resonance imaging (MRI) increases signal-to-noise ratio leading to improved image quality. However, its clinical relevance in clinically isolated syndrome suggestive of multiple sclerosis remains uncertain.

Objectives: The purpose of this study was to investigate how 3 T MRI affects the agreement between raters on lesion detection and diagnosis.

Methods: We selected 30 patients and 10 healthy controls from our ongoing prospective multicentre cohort. All subjects received baseline 1.5 and 3 T brain and spinal cord MRI. Patients also received follow-up brain MRI at 3-6 months. Four experienced neuroradiologists and four less-experienced raters scored the number of lesions per anatomical region and determined dissemination in space and time (McDonald 2010).

Results: In controls, the mean number of lesions per rater was 0.16 at 1.5 T and 0.38 at 3 T ( p = 0.005). For patients, this was 4.18 and 4.40, respectively ( p = 0.657). Inter-rater agreement on involvement per anatomical region and dissemination in space and time was moderate to good for both field strengths. 3 T slightly improved agreement between experienced raters, but slightly decreased agreement between less-experienced raters.

Conclusion: Overall, the interobserver agreement was moderate to good. 3 T appears to improve the reading for experienced readers, underlining the benefit of additional training.

Keywords: Multiple sclerosis; clinically isolated syndrome; interobserver variation; magnetic resonance imaging; multicentre study.

Conflict of interest statement

Declaration of Conflicting Interests: The author(s) declared the following potential conflicts of interest with respect to the research, authorship and/or publication of this article: M.H.J.H., J.B., I.D.K., S.R., R.C., N.C., E.S., M.An., M.Am., J.M.L. and B.I.L-W. have nothing to disclose. S.C. received meeting compensations from Novartis. P.P. has received founding for travel from Novartis, Genzyme and Bracco and speaker honoraria from Biogen. J.K. has accepted speaker and consultancy fees from Merck-Serono, Teva, Biogen, Genzyme, Roche and Novartis. C.O-G received honoraria as speaker from Biogen Idec, Bayer Schering, Merck-Serono, Teva, Genzyme and Novartis. J.W. is CEO of MIAC AG, has received research grants from the German Ministries of Science and Economy, the European Union and from Novartis. He received speaker honoraria from Bayer, Biogen, Genzyme Sanofi, Novartis and Teva, and he served for advisory boards for Novartis, Biogen, Genzyme and Roche. O.C. is an Associate Editor of Neurology, and she serves as consultant for Novartis, Roche, Genzyme and Teva, and payments are made to the institution. C.G. received fees as speaker for Bayer Schering Pharma, Sanofi-Aventis, Genzyme, Biogen, Teva, Novartis and Merck-Serono and received a grant for research by Teva. C.L. holds an endowed professorship supported by the Novartis foundation, has received consulting and speaker’s honoraria from Biogen Idec, Bayer Schering, Novartis, Sanofi, Genzyme and TEVA and has received research scientific grant support from Merck-Serono and Novartis. A.R. serves on scientific advisory boards for Biogen Idec, Novartis, Genzyme and OLEA Medical, and on the editorial board of the American Journal of Neuroradiology and Neuroradiology, has received speaker honoraria from Bayer, Genzyme, Sanofi-Aventis, Bracco, Merck-Serono, Teva Pharmaceutical Industries Ltd, Stendhal, Novartis and Biogen Idec and has research agreements with Siemens AG. F.B. serves on the editorial boards of Brain, Neurology, Neuroradiology, Multiple Sclerosis Journal and Radiology and serves as a consultant for Bayer Schering Pharma, Sanofi-Aventis, Genzyme, Biogen, Teva, Novartis, Roche, Synthon BV and Jansen Research. M.P.W. serves on the editorial boards of Neuroradiology, Journal of Neuroimaging, European Radiology, Frontiers of Neurology and serves as a consultant for Roche, Novartis and Biogen.

Figures

Figure 1.
Figure 1.
Study protocol. DIR: double inversion recovery; EDSS: Expanded Disability Status Scale; FLAIR: fluid-attenuated inversion recovery; FU: follow-up; PD: proton density; SDMT: standard digit modalities test; SE: spin-echo; T: Tesla.
Figure 2.
Figure 2.
1.5 and 3 T MRI scans of two CIS patients. 1. 3DFLAIR brain scans of one CIS patient presenting with optic neuritis: (a) baseline scan on 3 T with no brain lesions, (b) follow-up scan on 3 T showing two new T2 lesions in the corpus callosum, (c) follow-up scan on 1.5 T on which only one of the new lesion can be identified. 2. Baseline (a) 3 and (b) 1.5 T 3DFLAIR brain scans of one CIS patient presenting with a spinal cord syndrome. All raters identified additional periventricular and juxtacortical lesions on 3 T MRI leading to dissemination in space, while only three experienced raters on 1.5 T.
Figure 3.
Figure 3.
Agreement on lesions per anatomical region per field strength. Agreement between the eight raters on the involvement of an anatomical region, calculated with Cohen’s kappa scores, and on the exact number of lesions per anatomical regions, calculated with weighted Conger’s kappa scores. The horizontal lines indicate the cut-off values of 0.41 for moderate agreement, 0.61 for substantial agreement and 0.81 for good agreement. BL: baseline; E: enhancement; FU: follow-up; IT: infratentorial; JC: juxtacortical; PV: periventricular; SC: spinal cord.
Figure 4.
Figure 4.
Effect of experience on agreement on involvement per anatomical region per field strength. Calculated by subtracting Cohen’s kappa for 3 T by Cohen’s kappa for 1.5 T. BL: baseline; E: enhancement; FU: follow-up; IT: infratentorial; JC: Juxtacortical; PV: periventricular; SC: spinal cord; T: Tesla.
Figure 5.
Figure 5.
Agreement on the diagnosis per field strength dependent on experience of the raters. Calculated using Cohen’s kappa scores. The horizontal lines indicate the cut-off values 0.41 for moderate agreement, 0.61 for substantial agreement and 0.81 for good agreement. DIS: dissemination in space; DIT: dissemination in time; MS: diagnosis of multiple sclerosis.

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