Temporal and spatial profile of brain diffusion-weighted MRI after cardiac arrest

Diffusion-weighted magnetic resonance imaging of the brain is a promising technique to help predict functional outcome in comatose survivors of cardiac arrest. We aimed to evaluate prospectively the temporal-spatial profile of brain apparent diffusion coefficient changes in comatose survivors during the first 8 days after cardiac arrest.

Apparent diffusion coefficient values were measured by 2 independent and blinded investigators in predefined brain regions in 18 good- and 15 poor-outcome patients with 38 brain magnetic resonance imaging scans and were compared with those of 14 normal controls. The same brain regions were also assessed qualitatively by 2 other independent and blinded investigators.

In poor-outcome patients, cortical structures, in particular the occipital and temporal lobes, and the putamen exhibited the most profound apparent diffusion coefficient reductions, which were noted as early as 1.5 days and reached a nadir between 3 and 5 days after the arrest. Conversely, when compared with normal controls, good-outcome patients exhibited increased diffusivity, in particular in the hippocampus, temporal and occipital lobes, and corona radiata. By qualitative magnetic resonance imaging readings, 1 or more cortical gray matter structures were judged to be moderately to severely abnormal in all poor-outcome patients except for the 3 patients imaged within 24 hours after the arrest.

Brain diffusion-weighted imaging changes in comatose, postcardiac arrest survivors in the first week after the arrest are region and time dependent and differ between good- and poor-outcome patients. With increasing use of magnetic resonance imaging in this context, it is important to be aware of these relations.