Improving Awakening Prognostication After Non Anoxic Coma Using PET-MRI in Intensive Care Unit
Condition: Coma
MeSH terms: Coma
Study type: Interventional

Summary: 
      In last decades, several advances in the neuro-intensive management have lead to decrease
      mortality in Intensive Care Units. A significant morbidity remains as patients survive after
      a traumatic coma with uncertain quality of awakening and a high risk of functional
      disability. Predicting awareness recovery and functional disability of those who will awake
      constitutes a major challenge to inform patients' relatives, to give the best chances in
      terms of rehabilitation resources or to adapt intensive cares to a reasonable level. Tools
      currently available are not sufficient neither to predict bad awakening outcome nor to
      predict good functional outcome. In many countries, life's support cessation is a constant
      call for robust evaluation as soon as possible in ICU but it is mandatory to reach a positive
      predictive value of non-awaking close to 100%. Many clinical, electro-physiological,
      biological, radiological and functional parameters have been conducted with comatose patients
      assuming the purpose to predict outcome. Regarding unfavourable outcome, the gold standard is
      the abolition of the N20 component of somatosensory evoked potentials but the specificity is
      high enough only for patients with anoxic coma. Several neurophysiological markers such as
      MMN, P300 are correlated to a favourable outcome but the sensitivity and specificity remains
      low for patients who suffered a severe traumatic brain injury. New Diffusion Tensor imaging
      sequences provide complementary information to detect small structural lesions (diffuse
      axonal lesions). Recently, functional MRI analyzing Resting State has also been proposed as a
      prognostic marker during coma. PET using Fluoro-Desoxy-Glucose is able to assess the
      metabolism in key regions of the awakening network in either anaesthesia or sleep. Recent
      studies have reported interesting results at the chronic stage but to knowledge, these tools
      have only been used to address pathophysiology's issues and never to improve coma prognosis
      at the initial stage. The investigators hypothesize that the heterogeneity of the population
      requires a global and accurate assessment of the central nervous system, combining
      structural, metabolic and functional information in order to refine the prognosis.

      The protocol integrates in one-sequence most radiological markers of brain injury within a
      unique PET-MRI in Lyon. The most relevant originality of the study consists in confronting
      FDG-PET and MRI sequences to a large clinical, electrophysiological and biological battery.
      The added clinical value would be to question the synergistic effect of each parameter and to
      find out which ones are the most useful for awakening prediction, as they have not been
      compared in a multi-parametric database.

      PET-MRI, as a new device combining physiological and prognostic questioning, allows us:

        -  to implement a more integrative physio-pathological analysis

        -  to avoid the cofounding effect of awareness' fluctuations in recording simultaneously
           multiple functional imaging techniques.

      The RS will be analyzed at 2 epochs in order to assess the stability of brain connectivity,
      related to neuronal activity (glucose metabolism) and brain perfusion.
    


Intervention name(s): PET-MRI
Intervention type(s): Radiation
Intervention description(s): 18Fluoro-Desoxy-Glucose's infusion for PET (glucose neural metabolism assessment, with quantitative information permitted by radioactivity monitoring through arterial catheter ; dosage = 1,5 MBq/Kg + 18,5 MBq as loading dose 5 min= Outside the scanner, Installation and movement management: Curare+/- sedative injection with standardized routine care protocol 10 min= Outside the scanner, Starting PET continuous acquisitionT= 0, Morphological MRI sequences- 3DT1, 3DFlair, T2SE, T2 HR on brainstem, Susceptibility and simple Diffusion Weighted Imaging-Specifically dedicated MR sequences based upon clinical issues 25 min, MRI in Resting state N°1 (global short-term functional connectivity)13 min, MRI DTI acquisition, 64 directions, sensitive to white matter injury 8 min, IRM in 2D-Arterial Spin Labelling:Quantitative Cerebral blood flow information (no Gadolinium)->8 min, IRM in Resting state 2 (repeated occurrence to assess stationarity) 13 min, End of PET continuous acquisition
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: coma; prognosis; comparative study; functional imaging; PET-MRI; electrophysiology