Single-subject independent component analysis-based intensity normalization in non-quantitative multi-modal structural MRI Authors

New publication in Hum Brain Mapp. 2017 Apr 22. doi: 10.1002/hbm.23615.

Papazoglou S, Würfel J, Paul F, Brandt AU, Scheel M.

Non-quantitative MRI is prone to intersubject intensity variation rendering signal intensity level based analyses limited. Here, we propose a method that fuses non-quantitative routine T1-weighted (T1w), T2w, and T2w fluid-saturated inversion recovery sequences using independent component analysis and validate it on age and sex matched healthy controls. The proposed method leads to consistent and independent components with a significantly reduced coefficient-of-variation across subjects, suggesting potential to serve as automatic intensity normalization and thus to enhance the power of intensity based statistical analyses. To exemplify this, we show that voxelwise statistical testing on single-subject independent components reveals in particular a widespread sex difference in white matter, which was previously shown using, for example, diffusion tensor imaging but unobservable in the native MRI contrasts. In conclusion, our study shows that single-subject independent component analysis can be applied to routine sequences, thereby enhancing comparability in-between subjects. Unlike quantitative MRI, which requires specific sequences during acquisition, our method is applicable to existing MRI data.

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Contribution of blood vessels to retinal nerve fiber layer thickness in NMOSD

New publication in Neurol Neuroimmunol Neuroinflamm. 2017 Apr 18;4(3):e338. doi: 10.1212/NXI.0000000000000338. eCollection 2017 May.

Oertel FC, Zimmermann H, Mikolajczak J, Weinhold M, Kadas EM, Oberwahrenbrock T, Pache F, Bellmann-Strobl J, Ruprecht K, Paul F, Brandt AU.

Neuromyelitis optica spectrum disorders (NMOSDs) are relapsing inflammatory demyelinating disorders with optic neuritis (ON) as the hallmark. ON causes neuroaxonal damage to the optic nerve and retina, regularly leading to severely impaired visual acuity (VA).

Peripapillary retinal nerve fiber layer (pRNFL) thickness measured by optical coherence tomography (OCT) has been increasingly recognized as a marker for neuroaxonal damage and correlate of visual dysfunction. As such, pRNFL is implemented as an outcome in clinical trials of ON-associated disorders. Blood vessels (BVs) running within the pRNFL contribute approximately 13% to an average RNFL thickness2 and could present an important confounder when tracking small pRNFL changes or in diseases with severe thinning such as NMOSD. Against this background, the objective of this study was to investigate the influence of retinal BVs on pRNFL measurements in an NMOSD cohort.

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