Consistent and robust 4D whole-brain segmentation: Application to traumatic brain injury

We propose a consistent approach to automatically segmenting longitudinal magnetic resonance scans of pathological brains. Using symmetric intra-subject registration, we align corresponding scans. In an expectation-maximization framework we exploit the availability of probabilistic segmentation estimates to perform a symmetric intensity normalisation. We introduce a novel technique to perform symmetric differential bias correction for images in presence of pathologies. To achieve a consistent multi-time-point segmentation, we propose a patch-based coupling term using a spatially and temporally varying Markov random field. We demonstrate the superior consistency of our method by segmenting repeat scans into 134 regions. Furthermore, the approach has been applied to segment baseline and six month follow-up scans from 56 patients who have sustained traumatic brain injury (TBI). We find significant correlations between regional atrophy rates and clinical outcome: Patients with poor outcome showed a much higher thalamic atrophy rate (4.9 ± 3.4%) than patients with favourable outcome (0.6 ± 1.9%).