OBJECTIVE: The relationship between microstructural abnormality in patients with traumatic brain injury (TBI) and hormone-secreting status remains unknown. In this study, we identified the role of the apparent diffusion coefficient (ADC) using a diffusion-weighted imaging (DWI) technique and to evaluate the association of such changes with hypopituitarism in TBI patients.

MATERIALS AND METHODS: Diffusion weighted images from 164 consecutive patients with TBI were processed and pituitary ADC was generated as a measure of microstructural change. Patients with TBI were further grouped with or without pituitary dysfunction based on the excretion status of the pituitary at one month post injury. MRI data and laboratory findings were analyzed blindly. 30 healthy controls were enrolled. Mean ADC values were compared among the three groups and correlational studies were also performed. The neurological outcome was assessed by the Glasgow outcome scale (GOS) scores at 6 months post injury.  

RESULTS: Our study included 84 TBI patients with pituitary dysfunction and 80 TBI patients without pituitary dysfunction. Hormone secretion status was strongly associated with the ADC value (r=-0.651, P=0.001). There was significant difference in ADC value between those with higher prolactin (PRL) and normal PRL level (P<0.05). In addition, the ADC value was correlated with the neurological outcome at 6 month following TBI (r=0.602, P<0.05).

CONCLUSION: Using the DWI technique, we confirm that the ADC in pituitary is correlated with the hormone-secreting status in TBI patients. We also demonstrate that the pituitary ADC may become a novel biomarker to assess the pituitary function in patients with TBI.