Dopaminergic Disruption Induced by Traumatic Coma: Dopaminergic Pathways Abnormalities and Biomarkers of Recovery Using MRI and 18F-LBT-999 PET

Inclusion Criteria: For All Participants: * Aged 18-65 years. * Affiliated with or beneficiary of a social security system. * Signed informed consent provided by the participant or a trusted representative (for patients). For all TBI Participant * Hospitalized for a non-penetrating traumatic brain injury (TBI) occurring within the last 30 days, with traumatic coma (Glasgow Coma Scale (GCS) \< 10 and motor score (M) \< 6) at hospital admission. * Sedative treatments discontinued for more than 48 hours. * Clinically stable (no hemodynamic, respiratory, or metabolic instability requiring specific interventions that contraindicate medical transfer to the imaging center). For the TBI-COMA Group: \- Severe TBI characterized by prolonged coma, defined as an initial GCS \< 10 with M \< 6, and no recovery of consciousness at inclusion (GCS \< 10 with M \< 6). For the TBI-REC Group: * Severe TBI characterized by prolonged coma, defined as an initial GCS \< 10 with M \< 6, with recovery of consciousness evidenced by simple command-following (GCS ≥ 10 with M = 6) at inclusion. * For Healthy Controls: Matched by age (± 2 years) and sex to patients in the TBI-COMA group. Exclusion Criteria: For All Participants: * Pregnant or breastfeeding women * Contraindications to MRI * Known allergy to the PET radiotracer or its excipients. * History of conditions affecting the dopaminergic system * Individuals under legal protection measures * Current treatment with dopaminergic agonists or antagonists. For Patients Only: * Coma due to causes other than TBI. * Decompressive craniectomy resulting in anatomical alterations incompatible with standardized image analysis (e.g., midline shift \> 2 cm). For Healthy Controls Only: * Women of childbearing potential without effective contraception. * Women unwilling to maintain effective contraception during the 30-day study period.