Quantitative Analysis of Regional Pituitary Perfusion by Dynamic Contrast Enhanced T1 MR Imaging

We sought to investigate quantitatively the topographical perfusion characteristics of the adenohypophysis using dynamic contrast-enhanced (DCE) MR imaging in idiopathic growth hormone deficiency (IGHD) and idiopathic central precocious puberty (ICPP) patients. Another aim of this study is to investigate the relation of the hormone levels in IGHD and ICPP with respect to the regional perfusion parameter alternations. We hypothesize that endocrine disease is topographically dependent and pituitary blood perfusion might play a role. Our study try to address these regional perfusion impairments by T1 dynamic contrast enhanced MR imaging combined with the pharmacokinetic model.
Dynamic contrast enhanced T1-weighted MR imaging has the capability of exploiting tissue perfusion properties via quantitative analysis using appropriate tracer kinetic model. But, the structure surrounding the pituitary gland such as air and bone may deteriorate the field homogeneity, making DCE MR imaging difficult to implement with satisfactory proper image quality. Therefore, past studies with only single-slice acquisition limit the scope to evaluate the pituitary perfusion properties. We attempt to conquer the technical limitation of regional pituitary perfusion through the combination of fast spin echo T1 dynamic contrast enhanced MR imaging with pharmacokinetic model analysis. The perfusion parameters can further be derived quantitatively and data analysis can be extended to topographical perfusion characteristics of the adenohypophysis.
The study found that time to peak (TTP) for the IGHD group was significantly prolonged than normal control (p<0.005). The prolonged TTP in IGHD was found to be diffuse and lack of lateralization. The levels of growth hormone deficiency were negatively correlated with the peak enhancement and slope of wash-in phase, suggesting increased blood volume in IGHD within the pituitary gland. Another group study in ICPP showed that peak enhancement was significantly decreased than normal control (p<0.005) and the abnormality was found to be diffuse and lack of posteriority. The increasing levels of luteinizing hormone were negatively correlated with the slope of wash-in phase, suggesting decreased perfusion efficiency in ICPP within the pituitary gland.
In conclusion, dynamic contrast-enhanced fast spin echo T1-weighted MR imaging and Brix model analysis allow multi-slice and multi-regional quantitative evaluation of the anterior pituitary gland in endocrine disease such as IGHD and ICPP. This technique may help to approach the clinical question when the morphological imaging feature alone does not explain the clinical findings.