What is the role of neuroimaging in predicting neurologic outcome after cardiac arrest?
A: Computed tomographic (CT) images are usually normal immediately after a cardiac arrest, but by day 3 they often show brain swelling and inversion of the gray–white densities in patients with a poor outcome. Further study is needed to assess the clinical use of these findings in establishing prognosis. Magnetic resonance imaging (MRI) has also been proposed as a means of assessing prognosis after cardiac arrest, but limited data call its use into question. The use of apparent diffusion coefficient (ADC) mapping was reported to add greater precision in predicting a poor outcome. MR spectroscopy (e.g., for pH and N-acetylaspartate, a neuronal marker) has been reported to correlate with a poor outcome in small studies, but more data are needed. Measures of cerebral metabolism with positron-emission tomography and determination of intracranial pressure, brain oxygen, or jugular venous oxygenation have not appeared sufficiently discriminatory for a poor outcome to be clinically useful, although studies are small.
New England Journal of Medicine - Vol. 361, No. 6, August 6, 2009