title: Decreased apparent diffusion coefficient in the pituitary and correlation with hypopituitarism in patients with traumatic brain injury.
abstract: OBJECTIVE
  The relationship between microstructural abnormality in patients with traumatic brain injury (TBI) and hormone-secreting status remains unknown. In this study, the authors aimed to identify 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 patients with TBI.
  
  
  METHODS
  Diffusion-weighted images were obtained in 164 consecutive patients with TBI within 2 weeks after injury to generate the pituitary ADC as a measure of microstructural change. Patients with TBI were further grouped into those with and those without hypopituitarism based on the secretion status of pituitary hormones at 6 months postinjury. Thirty healthy individuals were enrolled in the study and underwent MRI examinations for comparison. Mean ADC values were compared between this control group, the patients with TBI and hypopituitarism, and the patients with TBI without hypopituitarism; correlational studies were also performed. Neurological outcome was assessed with the Glasgow Outcome Scale (GOS) for all TBI patients 6 months postinjury.
  
  
  RESULTS
  In the TBI group, 84 patients had hypopituitarism and 80 had normal pituitary function. The pituitary ADC in TBI patients was significantly less than that in controls (1.83 ± 0.16 vs 4.13 ± 0.33, p < 0.01). Furthermore, the mean ADC was much lower in TBI patients with hypopituitarism than in those without pituitary dysfunction (1.32 ± 0.09 vs 2.28 ± 0.17, p < 0.05). There was also a significant difference in ADC values between patients with hyperprolactinemia and those with normal prolactin levels (p < 0.05). Additionally, the receiver operating characteristic curve analysis showed that the pituitary ADC could predict hypopituitarism with a sensitivity of 90.0% and a specificity of 90.1% at the level of 1.720 (ADC value). Finally, the ADC value was positively correlated with neurological outcome at 6 months following TBI (r = 0.602, p < 0.05).
  
  
  CONCLUSIONS
  Use of DWI demonstrated that the pituitary ADC is correlated with hormone-secreting status in TBI patients. The authors suggest that pituitary ADC may be a useful biomarker to predict pituitary function in patients with TBI.
authors: Department of Neurosurgery, Pudong New Area People's Hospital, Shanghai, China.
authors: Ping
authors: P
authors: Zheng
authors: Department of Neurosurgery, Pudong New Area People's Hospital, Shanghai, China.
authors: Bin
authors: B
authors: He
authors: Department of Neurosurgery, Pudong New Area People's Hospital, Shanghai, China.
authors: Yijun
authors: Y
authors: Guo
authors: Department of Neurosurgery, Pudong New Area People's Hospital, Shanghai, China.
authors: Jingsong
authors: J
authors: Zeng
authors: Department of Neurosurgery, Pudong New Area People's Hospital, Shanghai, China.
authors: Wusong
authors: W
authors: Tong
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000378:metabolism / Q000473:pathology; D001930:Brain Injuries / Q000473:pathology* / Q000503:physiopathology; D016022:Case-Control Studies; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D006801:Humans; D007018:Hypopituitarism / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D010902:Pituitary Gland / Q000378:metabolism / Q000473:pathology*; D010907:Pituitary Hormones / Q000378:metabolism; D011388:Prolactin / Q000378:metabolism; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D010907:Pituitary Hormones; D011388:Prolactin
keywords: ADC = apparent diffusion coefficient; DWI = diffusion-weighted imaging; GCS = Glasgow Coma Scale; GH = growth hormone; GOS = Glasgow Outcome Scale; ROI = region of interest; TBI = traumatic brain injury; TSH = thyroid-stimulating hormone; apparent diffusion coefficient; diffusion-weighted imaging; hypopituitarism; traumatic brain injury