Assessment of brain metabolic dysfunction using FDG PET/CT with subliminal visual stimuli in burn patients with PTSD

Objectives This study investigated the neural correlates of subliminal stimulation using RSVP with FDG-PET to assess the dydfunctional brain areas in PTSD patients.

Methods 10 burn patients with PTSD (mean age 39.0 years), 10 burn patients without PTSD (40.2) and 40 normal controls (46.4) were included in the study. They were all male patients and had any previous head trauma, neurologic or psychological problem or endocrinological disease. Resting FDG PET/ CT was taken in all subjects. Additional stress scan using rapid serial visual presentation (RSVP) was done in 20 burn patients. Images were analyzed with SPM8. We used two design types: two-sample t-test to compare between groups; paired t-test to compare resting and stress scans in the groups (voxel threshold 0.001, cluster level p value < 0.005).

Results Comparison between PTSD and normal control groups: At resting state, anterior cingulate cortex (ACC) and subgenual prefrontal cortex (PFC) represented relative metabolic decrease in PTSD group (T > 3.75, p < 0.035). At stress state, reduced metabolic activities were in left parahippocampal gyrus and subgenual PFC in PTSD group (T > 3.56, p < 0.012). Comparison of PTSD and burn control groups between resting and activated sates: In PTSD group, metabolic increases were in dorsomedial, ventrolateral and ventromedial PFC, ACC and left precuneus. (p < 0.021, T > 4.05). In burn control group, metabolic increases were in bilateral premotor cortexes and left auditary cortex (p < 0.021, T > 3.46).

Conclusions Subgenual PFC with reduced activity at resting and stress states is seem to be one of pathologic sites of PTSD and maybe related with impaired top-down regulation system. This area is also related with HPA axis activity, which considered to be disrupted in PTSD. Activation of prefrontal cortices with RSVP maybe suggests that the top-down regulation center is activated in patients with PTSD, who have increased arousal, and not in patients without PTSD.