The role of F-18 FDG PET/CT in the prognosis of patients with hypoxic/anoxic brain injury after cardio-circulatory arrest.

ABSTRACT

BACKGROUND: Advances in resuscitation techniques have resulted in more patients surviving cardio-circulatory arrest (CA) and consequently developing hypoxic/anoxic brain damage. The aim of this study is to evaluate the role of PET/CT (Positron Emission Tomography/Computerized Tomography scan) with F-18 FDG (F-18 fluorodeoxyglucose) during the early rehabilitative hospitalization phase in determining the V/C (Vermis/Cerebellar) ratio as a prognostic index to predict patient outcome, as defined by clinical evaluation scales. METHODS: This is a single-center retrospective study of 37 consecutive adult patients admitted to the neurorehabilitation center between January 2011 and June 2019. Functional status was measured by the following clinical scales FIM (Functional Indipendence Measure), LCFS (Levels of Cognitive Functioning Scale), GOS (Glasgow Outcome Scale) and CRS-R (Coma Recovery Scale-Revised). PET/CT with F-18 FDG as a functional imaging technique was used to calculate the V/C ratio as a ratio between the metabolism of the vermis and of the Cerebellar Hemisphere. RESULTS: A statistically significant correlation was observed between the V/C ratio and the delta values (difference between discharge and admission value) for each clinical evaluation scale (Delta FIM P=0.0014; Delta LCFS P=0.0003). A statistically significant difference was observed between the V/C ratio of patients with LCFS ≥4 that showed an improved outcome (defined as an improvement of at least two points in LCFS), and that of patients with LCFS <4 that did not improve (P=0.0011). A V/C ratio cut-off of 1.5 corresponded with a positive predictive power of 80% and a negative predictive power of 82%; a value <1.5 predicted a better outcome. CONCLUSIONS: Clinical evaluation scales when associated with F-18 FDG PET/CT measurement of metabolism, provide a more reliable prognosis. This allows for more focused rehabilitation treatment and better management of family members' expectation.