Background: Neuroimaging may prove useful in identifying cardiac arrest patients destined for a poor recovery, as certain patterns have been associated with a poor outcome. However, MRI changes evolve temporally and spatially, which may lead to misinterpretation and misclassification of patients.
Methods: Eight comatose patients following cardiac arrest underwent diffusion-weighted imaging (DWI) at two time points, and one patient underwent DWI at three time points. Each of the prespecified areas of each study were read as either "normal" or "abnormal" by two stroke neurologists. Neurological examinations, including GCS scores, were recorded on days 0, 1, 3, and 7. Outcomes were determined by the modified Rankin Scale (mRS), with poor outcome defined as mRS score ≥4 at 6 months.
Results: In the acute (<24 h) period, two patients exhibited changes on DWI and FLAIR in the cerebellum and basal ganglia. In the early subacute period (days 1-5), cortical abnormalities predominated, with a shift to more white matter changes in the late subacute period (days 6-12). We observed more widespread imaging abnormalities in patients with poor outcomes, and partial or full resolution of DWI abnormalities in the two patients with good outcomes.
Conclusions: MRI patterns after global hypoxic-ischemic injury follow a characteristic pattern with variable acute changes in the cortex, basal ganglia, and cerebellum, followed by predominantly cortical and white matter changes in the early and late subacute periods. Diffuse, persistent widespread changes on MRI may help to predict poor outcome.