Modeling traumatic brain injury combined with hemorrhagic shock in rats: Neurological assessment and PET imaging with 18F-fluorodeoxyglucaric acid

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. Hemorrhagic shock (HS) aggravates tissue injury and complicates TBI recovery. We studied the combined insult of mild TBI and HS and investigated the impact of varying loss of blood volume on neurologic deficit and brain lesion volume. A novel positron emission tomography (PET) technique was employed to monitor tissue injury. Male Sprague Dawley rats received mTBI by controlled cortical impact (CCI) followed by withdrawal of 0%, 30-40%, 45%, or 50% of blood (mTBI, mTBI+HS[≤]40%, mTBI+HS45%, and mTBI+HS50%, respectively). Neurological deficit (mNSS= 5.6, 7.6, and 12.3) and mortality (2/12, 2/6, and 7/12) were worse in mTBI+HS[≤]40%, mTBI+HS45%, and mTBI+HS50%, respectively than in mTBI alone rats (no death; mNSS=3.3). Histologic lesion size increased 3.5-fold in mTBI+HS50% compared to mTBI alone and the infarct-avid PET agent 18F-fluorodeoxyglucaric acid (FGA) proportionately detected tissue necrosis in mTBI+HS50% rats. Based on these results, we conclude that HS aggravates mTBI-induced neurological deficits, tissue injury and mortality. PET/18F-FGA as an imaging marker can detect the extent of injury in a non-invasive manner.