A semi-automated measuring system of brain diffusion and perfusion magnetic resonance imaging abnormalities in patients with multiple sclerosis based on the integration of coregistration and tissue segmentation procedures.

BACKGROUND: Diffusion-weighted imaging (DWI) and perfusion-weighted imaging (PWI) abnormalities in patients with multiple sclerosis (MS) are currently measured by a complex combination of separate procedures. Therefore, the purpose of this study was to provide a reliable method for reducing analysis complexity and obtaining reproducible results. METHODS: We implemented a semi-automated measuring system in which different well-known software components for magnetic resonance imaging (MRI) analysis are integrated to obtain reliable measurements of DWI and PWI disturbances in MS. RESULTS: We generated the Diffusion/Perfusion Project (DPP) Suite, in which a series of external software programs are managed and harmonically and hierarchically incorporated by in-house developed Matlab software to perform the following processes: 1) image pre-processing, including imaging data anonymization and conversion from DICOM to Nifti format; 2) co-registration of 2D and 3D non-enhanced and Gd-enhanced T1-weighted images in fluid-attenuated inversion recovery (FLAIR) space; 3) lesion segmentation and classification, in which FLAIR lesions are at first segmented and then categorized according to their presumed evolution; 4) co-registration of segmented FLAIR lesion in T1 space to obtain the FLAIR lesion mask in the T1 space; 5) normal appearing tissue segmentation, in which T1 lesion mask is used to segment basal ganglia/thalami, normal appearing grey matter (NAGM) and normal appearing white matter (NAWM); 6) DWI and PWI map generation; 7) co-registration of basal ganglia/thalami, NAGM, NAWM, DWI and PWI maps in previously segmented FLAIR space; 8) data analysis. All these steps are automatic, except for lesion segmentation and classification. CONCLUSION: We developed a promising method to limit misclassifications and user errors, providing clinical researchers with a practical and reproducible tool to measure DWI and PWI changes in MS.

Longitudinal analysis of cerebral aqueduct flow measures: multiple sclerosis flow changes driven by brain atrophy.

BACKGROUND: Several small cross-sectional studies have investigated cerebrospinal fluid (CSF) flow dynamics in multiple sclerosis (MS) patients and have reported mixed results. Currently, there are no longitudinal studies that investigate CSF dynamics in MS patients. OBJECTIVE: To determine longitudinal changes in CSF dynamics measured at the level of aqueduct of Sylvius (AoS) in MS patients and matched healthy controls (HCs). MATERIALS AND METHODS: Forty (40) MS patients and 20 HCs underwent 3T MRI cine phase contrast imaging with velocity-encoded pulse-gated sequence at baseline and 5-year follow-up. For atrophy determination, MS patients underwent additional high-resolution 3D T1-weighted imaging. Measures of AoS cross-sectional area (CSA), average systolic and diastolic velocity peaks, maximal systolic and diastolic velocity peaks and average CSF flow rates were determined. Brain atrophy and ventricular CSF (vCSF) expansion rates were determined. Cross-sectional and longitudinal changes were derived by analysis of covariance (ANCOVA) and paired repeated tests. Confirmatory general linear models were also performed. False discovery rate (FDR)-corrected p-values lower than 0.05 were considered significant. RESULTS: The MS population demonstrated significant increase in maximal diastolic peak (from 7.23 to 7.86 cm/s, non-adjusted p = 0.037), diastolic peak flow rate (7.76 ml/min to 9.33 ml/min, non-adjusted p = 0.023) and AoS CSA (from 3.12 to 3.69 mm2, adjusted p = 0.001). The only differentiator between MS patients and HCs was the greater AoS CSA (3.58 mm2 vs. 2.57 mm2, age- and sex-adjusted ANCOVA, p = 0.045). The AoS CSA change was associated with vCSF expansion rate (age- and sex-adjusted Spearman's correlation r = 0.496, p = 0.019) and not with baseline nor change in maximal velocity. The expansion rate of the vCSF space explained an additional 23.8% of variance in change of AoS CSA variance when compared to age and sex alone (R2 = 0.273, t = 2.557, standardized ß = 0.51, and p = 0.019). CONCLUSION: MS patients present with significant longitudinal AoS enlargement, potentially due to regional atrophy changes and ex-vacuo expansion of the aqueduct.

Evidence for cervical cord tissue disorganisation with aging by diffusion tensor MRI.

This study investigated the influence of normal aging on cervical cord volumetry and diffusivity changes and assessed whether magnetic resonance imaging (MRI) abnormalities of the aging cervical cord and brain are associated. Conventional and diffusion tensor (DT) MRI of the brain and cervical cord were acquired from 96 healthy subjects (age range=13-70 years). Cross-sectional area, mean diffusivity (MD) and fractional anisotropy (FA) of the cervical cord were measured. Volumetry and diffusivity metrics were also obtained for the brain white matter (WM) and grey matter (GM) (overall and cortical). No cervical cord lesions were seen on conventional MR images from all subjects. Degenerative vertebral column changes (not associated to cord compression) were found in 41 subjects (43%). Average FA of the cervical cord, but not average MD and cross-sectional area, was correlated with age (r=-0.70, p<0.001). Additionally, T2 brain lesion volume, normalised brain volume (NBV), normalised global and cortical brain GM volumes and average MD of the brain GM and WM also correlated with age (r values ranging from -0.83 to 0.62). Only brain WM average FA was weakly correlated with cervical cord average FA (r=0.25, p=0.02). The final multivariate model retained cord average FA (r=-0.37, p<0.001), normalised cortical GM volume (r=-0.56, p<0.001) and NBV (r=-0.22, p=0.04) as independent correlates of age (r2=0.76). Cervical cord is vulnerable to aging. The decrease of FA, in the absence of atrophy and MD changes, suggests gliosis as the most likely pathological feature of the aging cord.