The number of optic neuritis attacks is a potential confounder when comparing patients with NMO vs. controls by voxel-based neuroimaging analysis

• Published in: Acta radiologica (1987) Vol. 57; no. 8; p. 985
• Main Authors: Sánchez-Catasús, Carlos A, Cabrera-Gomez, José, Almaguer Melián, William, Bosch Bayard, Jorge, Rodríguez Rojas, Rafael, Valdes-Sosa, Pedro
• Format: Journal Article
• Language: English
• Published: England 01.08.2016
• Subjects: Adult; Case-Control Studies; Female; Humans; Image Interpretation, Computer-Assisted - methods; Magnetic Resonance Imaging - methods; Male; Middle Aged; Neuroimaging - methods; Neuromyelitis Optica - diagnostic imaging; Neuromyelitis Optica - pathology; Optic Neuritis - diagnostic imaging; Optic Neuritis - pathology; Reproducibility of Results; Tomography, Emission-Computed, Single-Photon - methods; Magnetic resonance imaging (MRI); voxel-based statistical analysis; SPECT; neuromyelitis optica; optic neuritis attacks
• ISSN: 1600-0455
• DOI: 10.1177/0284185115610935

Voxel-based morphometric (VBM) studies in neuromyelitis optica (NMO) have shown limited reproducibility. A previous study suggests that the number of optic neuritis (ON) attacks may be a confounding factor when comparing NMO patients with controls if it is not taken into account during VBM analysis. To investigate the potential confounding effect of the number of ON attacks, for both tissue volumes and perfusion by voxel-based statistical analysis. Volumetric magnetic resonance imaging (MRI) and perfusion SPECT were obtained from 15 controls and two patient subgroups: subgroup I was composed of nine patients with one or two ON attacks; and subgroup II of six patients with three or four ON attacks. We performed non-parametric voxel-based comparison of tissue volumes and perfusion between controls versus the two patient subgroups and for the whole patient group. Subgroup I presented no volume reductions, contrary to subgroup II that showed unequivocal reduction. We also found hypoperfusion in different brain regions in different subgroups. The results were quite different for the whole patient group. These findings highlight the confounding effect of the number of ON attacks, providing a new methodological insight that could explain the limited reproducibility of previous VBM studies in NMO.