Diffusion and perfusion MRI of the brain in comatose patients treated with mild hypothermia after cardiac arrest: a prospective observational study.

BACKGROUND: Outcome for resuscitated cardiac arrest (CA) patients is poor. The 1-year survival rate with favourable neurological outcome (CPC 1-2) after out-of-hospital CA is reported to be 4%. Among resuscitated patients treated within an ICU, approximately 50% regain consciousness, whereas the other 50% remain comatose before they die. Induced hypothermia significantly improves the neurological outcome and survival in patients with primary CA who remain comatose after return of spontaneous circulation.

AIM: To evaluate magnetic resonance imaging (MRI) changes in resuscitated CA patients remaining in coma after treatment with hypothermia.

METHODS: This prospective, observational study comprised 20 resuscitated CA patients who remained in coma 3 days after being treated with mild hypothermia (32-34 degrees C during 24h). Diffusion and perfusion MRI of the entire brain was performed approximately 5 days after CA. Autopsy was done on two patients.

RESULTS: The largest number of diffusion changes on MRI was found in the 16 patients who died. The parietal lobe showed the largest difference in number of acute ischaemic MRI lesions in deceased compared with surviving patients. Perfusion changes, > or = +/-2 SD compared with healthy volunteers from a previously published cerebral perfusion study, were found in seven out of eight patients. The autopsies showed lesions corresponding to the pathologic changes seen on MRI.

CONCLUSION: Diffusion and perfusion MRI are potentially helpful tools for the evaluation of ischaemic brain damage in resuscitated comatose patients treated with hypothermia after CA.