Application of ¹⁸F-FDG brain PET for survival prediction in a rat model of hanging-induced hypoxic brain injury

Accurate prediction of survival outcomes after hanging is a crucial and challenging issue in comatose survivors. In this preclinical study, we evaluated the potential utility of using brain glucose metabolism as measured by fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET) for survival prediction in a rat model of hanging-induced hypoxic brain injury (HBI).

HBI was induced by mechanical hanging using Sprague Dawley rats. ¹⁸F-FDG brain PET images were acquired in 26 HBI rats three hours post-injury (3 h post-injury) and 4 controls. During the 1 month follow-up period, HBI rats were further classified as survivors (n = 15) and nonsurvivors (n = 11). Between-group regional (standardized uptake values normalized to the reference whole brain = SUVR_WB, cerebellum = SUVR_CB, and pons = SUVR_pons) and voxel-based analyses were performed. The prognostic value of the SUVR was tested for overall survival (OS). In addition, diffusion-weighted imaging (DWI) was performed in 2 controls and 5 HBI rats (3 survivors, 2 nonsurvivors, 3 h post), and an apparent diffusion coefficient (ADC) map was generated.

The nonsurvivor group showed a significantly lower SUVR_WB, SUVR_CB, and SUVR_pons of the cerebral cortices than the survivor group (all p < 0.001). Voxel-based comparison also demonstrated significant reduction in the nonsurvivor group compared with the survivor group (family-wise error-corrected p < 0.05). However, there was no significant difference between controls and survivors. Of 3 reference regions, the SUVR_pons demonstrated the largest difference between the survivor and nonsurvivor groups. With an optimal cutoff value of 1.12 (AUC 0.952, p < 0.001), the SUVR_pons predicted survival outcomes with a sensitivity of 81.8% and specificity of 100%. The OS of the low SUVR_pons group was significantly shorter than that the high SUVR_pons group (p < 0.001). The mean ADC values of each brain region showed no significant difference according to survival outcomes.

These results suggest the potential utility of ¹⁸F-FDG brain PET for predicting survival in hanging-induced HBI.