Comparison of two different analysis approaches for DTI free-water corrected and uncorrected maps in the study of white matter microstructural integrity in individuals with depression

Abstract

Diffusion tensor imaging (DTI) has often been used to examine white matter (WM) tract abnormalities in depressed subjects, but these studies have yielded inconsistent results, probably, due to gender composition or small sample size. In this study, we applied different analysis pipelines to a relatively large sample of individuals with depression to determine whether previous findings in depression can be replicated with these pipelines. We used a "standard" DTI algorithm and maps computed through a free-water (FW) corrected DTI. This latter algorithm is able to identify and separate the effects of extracellular FW on DTI metrics. Additionally, skeletonized and WM voxel-based analysis (VBA) methods were used. Using the skeletonized method, DTI maps showed lower fractional anisotropy (FA) in depressed subjects in the left brain hemisphere, including the anterior thalamic radiation (ATR L), cortical spinal tract (CST L), inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, and superior longitudinal fasciculus (SLF L). Differences in radial diffusivity (RD) were also found. For the VBA using RD, we found different results when we used FW uncorrected and corrected DTI metrics. Relative to the VBA approach, the skeletonized analysis was able to identify more clusters where WM integrity was altered in depressed individuals. Different significant correlations were found between RD and the Patient Health Questionnaire in the CST L, and SLF L. In conclusion, the skeletonized method revealed more clusters than the VBA and individuals with depression showed multiple WM abnormalities, some of which were correlated with disease severity Hum Brain Mapp 38:4690-4702, 2017. © 2017 Wiley Periodicals, Inc.

Anorexia nervosa and diffusion weighted imaging: An open methodological question raised by a systematic review and a fractional anisotropy anatomical likelihood estimation meta‐analysis

“…Moreover, the only two DWI studies out of 16 that found no differences in the acute phase of the disorder between AN and controls, were not representative of the FA alteration assessment, because they used a different analysis approach, or because they focused on different variables (e.g., the interhemispheric connectivity instead of the FA), so they are not useful to reach a conclusion (Canna et al, ; Pfuhl et al, ). By the way, Bergamino, Kuplicki, Victor, Cha, and Paulus () showed that the differences between free water‐corrected and uncorrected FA in a large sample of depressed subjects are significant for the number of clusters found in the VBM analysis, but not when a TBSS pipeline was applied (they just found a reduction in significant volumes). PVE is a methodological problem for structural neuroimaging studies and numerous authors have investigated how the previous literature might therefore be biased.…”

“…were not representative of the FA alteration assessment, because they used a different analysis approach, or because they focused on different variables (e.g., the interhemispheric connectivity instead of the FA), so they are not useful to reach a conclusion Pfuhl et al, 2016). By the way, Bergamino, Kuplicki, Victor, Cha, and Paulus (2017) showed that the differences between free water-corrected and uncorrected FA in a large sample of depressed subjects are significant for the number of clusters found in the VBM analysis, but not when a TBSS pipeline was applied (they just found a reduction in significant volumes should preferably be used when analyzing this data, as it appears to be less susceptible to PVE and this could be the gold standard method to evaluate the putative role of specific brain area in AN, like the fornix (Kaufmann et al, 2017).…”

Diffusion MRI free water is a sensitive marker of age-related changes in the cingulum

“…It has been shown that elimination of extracellular free water contamination improves the sensitivity and specificity of most measures derived from conventional DTI (Albi et al, 2017;Salminen et al, 2016;Sepehrband et al, 2019). Although this correction techniques exist and have been used in pathological conditions (Bergamino, Kuplicki, Victor, Cha, & Paulus, 2017;Dumont et al, 2019;Ji et al, 2017;Ofori et al, 2017;Tanner et al, 2019) to date the majority of diffusion MRI studies do not consider free water effects on heathy aging brain (Albi et al, 2017;Chad, Pasternak, Salat, & Chen, 2018). Moreover, while FWE was initially developed to correct DTI derived metrics, it has recently been shown that the extracellular free water fraction may be a sensitive marker of age-related microstructural changes (Chad et al, 2018).…”

A robust deconvolution method to disentangle multiple water pools in diffusion MRI

“…These approaches assume that the diffusion signal can be described by a single Gaussian process. However, at the imaging resolution typically achieved in a dMRI experiment – on the order of millimeters – this assumption is often violated …”

“…However, at the imaging resolution typically achieved in a dMRI experimenton the order of millimetersthis assumption is often violated. [3][4][5] The vast majority of studies on multiple diffusion components are based on multi-compartment models, which require prior knowledge of the number and structure of the compartments. Originally, Le Bihan et al 6 proposed a bi-exponential formulation of the isotropic diffusion signal defining the intra-voxel incoherent motion (IVIM) model, which quantifies the effect of blood pseudo-diffusion on the dMRI signal.…”