Intracerebral hematomas disappear on T2*-weighted images during normobaric oxygen therapy.

BACKGROUND AND PURPOSE The aim of the present study was to investigate the effects of normobaric oxygen (NBO) therapy on T2*-weighted images of intracranial hemorrhages (ICHs). METHODS Two common models of ICH were performed in mice, and longitudinal T2*-weighted images of the hematomas were acquired under normoxia or NBO. The effects of NBO were also investigated on perfusion-weighted imaging, susceptibility-weighted imaging, and molecular imaging of vascular cell adhesion molecule-1 after ICH. Last, we performed neurological testing, including neuroscore, actimetry, and gait analysis (Catwalk), to study the influence of NBO on neurological outcome of mice presenting ICH. RESULTS Our results demonstrated that NBO, even during a short period of time, dramatically reduces the sensitivity of T2*-weighted imaging to detect ICH. Moreover, we provide evidence that the disappearance of ICH on T2*-weighted imaging could be used to improve accuracy of perfusion-weighted imaging and to allow molecular imaging after ICH. Importantly, a 30-minute NBO preparation 24 hours after ICH onset does not influence neurological outcome. CONCLUSIONS We provide an experimental demonstration that NBO significantly affects T2*-weighted imaging in ICH. Although this phenomenon could lead to inaccurate assessment of ICH volume, it could also be safely used to allow perfusion-weighted imaging and molecular imaging.