Intracerebral Hematomas Disappear on T2*-Weighted Images During Normobaric Oxygen Therapy

Abstract

ICH was induced by intrastriatal collagenase injection in 16 mice. One mouse died during the surgery and was therefore excluded from the analysis. Three behavioral tests were performed before the ICH and at +24 hours to assess the functional deficits induced by the ICH 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. in mice. The general state of the mice was assessed using a 5-point neuroscore scale (0=no apparent deficit; 1=slight deficit; 2=circling; 3=heavy circling or no movement at all; or 4=death). 4 The spontaneous global locomotor activity was quantified during 10 minutes using an actimeter (Imetronic, Pessac, France) as described previously.5 Briefly, global locomotor activity was quantified using activity cages equipped with horizontal infrared beams located across the long axis of the cage (IMETRONIC, France). Mice were placed in individual acrylic chambers (30×20×20 cm) for 10 minutes. The number of horizontal movements (horizontal crossings) was determined by breaks in movement-sensitive photobeams that were then converted into locomotor activity counts. A gait analysis was also performed using the Catwalk XT system (Noldus Information Technology, Wageningen, The Netherlands). The apparatus consists of an enclosed walkway (130×68×152 cm) on a glass plate that is traversed by the mice from one side to the other. Green light enters at the long edge of the plate and is completely internally reflected. Light is able to escape only at those areas where the animal's paws make contact with the glass plate; as a result, the light is scattered. Real footprints are captured by a high-speed video camera that is positioned underneath the walkway. The video camera transforms...

Potent Thrombolytic Effect of N -Acetylcysteine on Arterial Thrombi

“…7A) 14 . Unlike intravenous heparin administration (200 UI/kg in bolus, 75 minutes after collagenase administration) that led to hematoma expansion and high mortality rate, NAC treatment (400 mg/kg in bolus, 75 minutes after collagenase administration) failed to promote hematoma expansion, worsen clinical score or increase lesion sizes at any time points as compared to saline treated animals (Fig.…”

“…A unilateral striatal injection of collagenase type VII 14 (0.1 U in 0.5 μL of saline) was performed after placing Swiss male mice in a stereotaxic frame (coordinates: 0.5 mm anterior, 2.0 mm lateral, −3 mm ventral to the bregma). Solutions were injected by the use of a glass micropipette to minimize hemorrhage-unrelated tissular damage.…”

“…Solutions were injected by the use of a glass micropipette to minimize hemorrhage-unrelated tissular damage. Neurologic evaluation was performed blind to the experimental groups using the neuroscore scale, as previously described 14 .…”

Molecular magnetic resonance imaging of brain–immune interactions

“…In particular, hemorrhages and blood oxygen level dependent (BOLD) effects induce signal voids on T2*-weighted images which are comparable to MPIO-induced signal void and could therefore lead to false positive results. To overcome this, we demonstrated in a recent study in mice that a short preparation time (30 min) of normobaric hyperoxia can be sufficient to transform deoxyhemoglobin (paramagnetic) into oxyhemoglobin (diamagnetic) by increasing the tissular concentration of O 2 ( Gaberel et al, 2013 ). Thus, the susceptibility effect of endogenous blood is blunted, allowing observing changes in signal intensity that are specific to the contrast agent injected.…”

“…This phenomenon, known as “blooming effect,” provides high sensitivity in vivo MRI detection, using only a small number of MPIO particles ( Shapiro et al, 2005 , 2006 ; Heyn et al, 2006 ). Third, MPIOs have very short blood half-life of 50–100 s ( Ye et al, 2008 ; Yang et al, 2010 ), allowing imaging immediately after injection ( Montagne et al, 2012 ; Gaberel et al, 2013 ; Gauberti et al, 2013 ). Finally, MPIOs are readily functionalized by covalent conjugation of ligands (monoclonal antibodies or their immunospecific fragments F(ab), single chain antibodies or peptides derived from phage display) to functional groups (amine, carboxyl acid or p -toluene sulphydryl (tosyl)) on the MPIOs surface.…”