STEAM — Statistical Template Estimation for Abnormality Mapping: A personalized DTI analysis technique with applications to the screening of preterm infants

Abstract

We introduce the STEAM DTI analysis engine: a whole brain voxel-based analysis technique for the examination of diffusion tensor images (DTIs). Our STEAM analysis technique consists of two parts. First, we introduce a collection of statistical templates that represent the distribution of DTIs for a normative population. These templates include various diffusion measures from the full tensor, to fractional anisotropy, to 12 other tensor features. Second, we propose a voxel-based analysis (VBA) pipeline that is reliable enough to identify areas in individual DTI scans that differ significantly from the normative group represented in the STEAM statistical templates. We identify and justify choices in the VBA pipeline relating to multiple comparison correction, image smoothing, and dealing with non-normally distributed data. Finally, we provide a proof of concept for the utility of STEAM on a cohort of 134 very preterm infants. We generated templates from scans of 55 very preterm infants whose T1 MRI scans show no abnormalities and who have normal neurodevelopmental outcome. The remaining 79 infants were then compared to the templates using our VBA technique. We show: (a) that our statistical templates display the white matter development expected over the modeled time period, and (b) that our VBA results detect abnormalities in the diffusion measurements that relate significantly with both the presence of white matter lesions and with neurodevelopmental outcomes at 18months. Most notably, we show that STEAM produces personalized results while also being able to highlight abnormalities across the whole brain and at the scale of individual voxels. While we show the value of STEAM on DTI scans from a preterm infant cohort, STEAM can be equally applied to other cohorts as well. To facilitate this whole-brain personalized DTI analysis, we made STEAM publicly available at http://www.sfu.ca/bgb2/steam.

Diagnostic accuracy of early magnetic resonance imaging to determine motor outcomes in infants born preterm: a systematic review and meta‐analysis

“…A whole‐brain voxel‐based analysis found a greater extent of abnormalities on mean diffusivity, axial diffusivity, and radial diffusivity in infants with poorer motor outcome compared with infants with normal motor outcomes . Tract‐based spatial statistics applied to MRI acquired at PMA of 30 to 33 weeks found that infants with poorer motor outcomes had lower axial diffusivity and radial diffusivity in the corpus callosum, and internal and external capsule (but no association with fractional anisotropy) .…”

“…S1, online supporting information). Twenty‐six studies met the inclusion criteria and five further studies were identified by manual review of references of included papers . Demographic and clinical data extracted from the 31 studies included in this review are presented in Table .…”

“…Twenty‐six studies acquired early structural MRI data . Results of meta‐analyses are presented in Table and Figure .…”

“…Seventeen studies from nine distinct cohorts acquired early diffusion MRI data . Sensitivity and specificity of diffusion MRI findings to determine later motor outcomes and/or CP in individual studies are presented in Table .…”

“…Eight diffusion MRI studies reported associations between early MRI and motor outcomes . In white matter tracts (corpus callosum genu and splenium, PLIC, optic radiation), lower fractional anisotropy was associated with poorer motor outcomes .…”