Recently introduced hybrid PET/MR scanners provide the opportunity to measure simultaneously, and in direct spatial correspondence, both metabolic demand and functional activity of the brain, hence capturing complementary information on the brain's physiological state. Here we exploited PET/MR simultaneous imaging to explore the relationship between the metabolic information provided by resting-state fluorodeoxyglucose-PET (FDG-PET) and fMRI (rs-fMRI) in patients with disorders of consciousness.

Inclusion Criteria:

• DOC patients （acute, subacute or chronic period）: Coma, UWS and MCS.

Exclusion Criteria:

• neuromuscular blocking agents or sedative drugs administered within the prior 24 hours；
• unstable medical condition；
• mental implant in the brain

Distinguishing patients in unresponsive wakefulness syndrome, UWS [i.e. patients showing eyes opening but no behavioral evidence of consciousness ] from patients in minimally conscious state, MCS [i.e., patients showing minimal, inconsistent but clearly discernible intentional behaviors ] is pivotal for decision making in the entire care pathway of patients with DoC.