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Normalization of White Matter Intensity on T1‐Weighted Images of Patients with Acquired Central Nervous System Demyelination
Author(s) -
Ghassemi Rezwan,
Brown Robert,
Narayanan Sridar,
Banwell Brenda,
Nakamura Kunio,
Arnold Douglas L.
Publication year - 2014
Publication title -
journal of neuroimaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.822
H-Index - 64
eISSN - 1552-6569
pISSN - 1051-2284
DOI - 10.1111/jon.12129
Subject(s) - normalization (sociology) , medicine , white matter , multiple sclerosis , magnetic resonance imaging , nuclear medicine , pathology , radiology , psychiatry , sociology , anthropology
BACKGROUND Intensity variation between magnetic resonance images (MRI) hinders comparison of tissue intensity distributions in multicenter MRI studies of brain diseases. The available intensity normalization techniques generally work well in healthy subjects but not in the presence of pathologies that affect tissue intensity. One such disease is multiple sclerosis (MS), which is associated with lesions that prominently affect white matter (WM). OBJECTIVE To develop a T1‐weighted (T1w) image intensity normalization method that is independent of WM intensity, and to quantitatively evaluate its performance. METHODS AND SUBJECTS We calculated median intensity of grey matter and intraconal orbital fat on T1w images. Using these two reference tissue intensities we calculated a linear normalization function and applied this to the T1w images to produce normalized T1w (NT1) images. We assessed performance of our normalization method for interscanner, interprotocol, and longitudinal normalization variability, and calculated the utility of the normalization method for lesion analyses in clinical trials. RESULTS Statistical modeling showed marked decreases in T1w intensity differences after normalization ( P < .0001). CONCLUSIONS We developed a WM‐independent T1w MRI normalization method and tested its performance. This method is suitable for longitudinal multicenter clinical studies for the assessment of the recovery or progression of disease affecting WM.