| 1. To explore the appearance of the normal posterior pituitary lobe on MR T1WI and its underneath theory.2. To analysis the variability of the posterior pituitary signal intensity in the different age groups and different sexes. To discover the regularity of the signal intensity of normal posterior pituitary lobe wih age, and investigate the value of measurement about signal intensity of posterior pituitary lobe on midline sagittal T1-weighted images.752 cases examed in Southen Hospital during January 2007 to December 2009 were included in this study, with no intrasellar lesions and endocrine abnormalities. MRI imaging of the pituitary gland were acquired in these 752 cases.278 cases were examed by 1.5T MRI(147male and 141 female, aging from 1 to 81 years old, mean 34.2 years), and 474 cases were examed by 3.0T MRI(232male and 242 female patients, age from 2 to 84 years old, mean 42.2 years).There were 46cases between the age of 1 and 10,86 cases between the age of 11 and 20,94cases between the age of 21 and 30,169 cases between the age of 31 and 40,148 cases between the age of 41 and 50,132 cases between the age of 51 and 60,50 cases between the age of 61 and 70, and 27 cases between the age of 71 and 90.The mathines were GE 3.0T SIGNA EXITE and Siemens Vision Plus 1.5T superconducting whole body MRI system with head coil.Pituitary was examed on sagittal spin echo T1 weighted imaging with continuous thin layer. The parameters of 3.0T MRI scanner were:TR 2593ms, TE 21.0ms, slice thick 5.0mm, distance 1.0-1.5mm, FOV 24mm×24mm. The parameters of 1.5T MRI scanner were:TR 450.0ms, TE 14.0ms, slice thick 5.0mm, distancel.0-1.5mm, FOV 24mm×24mm.The clear images were selected. The datas were measured and analyzed in the PACS which was developed by Southen Hospital. The images were observed continuously and the final image was magnified to several times. To delineate the broad contours of the posterior pituitary and pons on medline sagittal T1-weighted images, and obtain the signal intensity ratio=posterior pituitary average gray/pons average gray.The SPSS 13.0 software was applied in this study. Comparing of the differences in the different age groups and genders. After test of homogeneity of variances (Lecene test), Welch test was applied to analyze the values as heterogeneity of variances, with Dunnett T3 test for two-two comparison. The statistical difference was granted as P<0.05.1. The posterior pituitary lobe can be seen on sagittal midline T1WI, with the hyper-intensity or iso-intensity in the pituitary fossa. The normal posterior pituitary lobes show high signal intensity (higher than the pons signal) in 694 cases, accounting for 92.3% of the total cases; and show isointense (similar to the pons signal) in 58 cases, accounting for 7.7% of the total cases. No appearing low signal in the normal posterior pituitary lobe.84 cases of child(<16 years) showed high signal posterior pituitary.2. To divide all cases into 8 age groups, taking 10 years as one group. To compare the means of the signal ratios in the different age groups. We found that the high intensity of the posterior pituitary lobe on T1WI tended to decline with age. The signal intensity was negatively correlated with age in Spearman correlation analysis. The correlation coefficient was-0.463. The statistically significant differences were found in SI values of the normal posterior pituitary lobe in T1WI between the sixth (51 to 60 years old) age groupe and the age groups before it. The statistically significant differences were not found in SI values of the normal posterior pituitary lobe in T1WI between the sixth (51 to 60 years old) age groupe and the seventh (61 to 70 years old) and eighth (71 to 90 years old) age groupe. Analyzed by independent samples T test, the statistically significant differences were not found in SI values of the normal posterior pituitary lobe in T1WI between the different gender. So we can conclude that the signal intensity of the posterior pituitary lobe has no business with gender.1. The neuroendocrine secretory granule with ADH is the main composition of the posterior pituitary lobe, and it is the foundation of the high signal on T1WI.2. The signal intensity was negatively correlated with age. The high intensity of the posterior pituitary lobe on T1WI tended to decline with age in both male and female.3. The iso-intensity of the posterior pituitary lobe can be a physiological change. But the low signal intensity suggests the pathological significance. It is needed to combine with the clinical materials and exclude the diagnosis of central diabetes insipidus particularly.To analyse MRI manifestations of central diabetes insipidus (CDI), and to evaluate the value of MRI in the diagnosis of CDI causes.The MR findings of 20 cases (examed in Southen Hospital during 2002.1 to 2010.2.) with central diabetes insipidus diagnosed by clinical were analyzed retrospectively. There were 12 male and 8 female, aging from 5 to 62 years old, mean 30.6 years. Enhancement scannings were performed in 10 cases(with 0.1mmol/kg).10 cases were examed on 3.0T equipments and the others were examed on 1.5T equipments The saddle area was examed on the sagittal and coronal spin echo T1 weighted imaging with continuous thin layer. The parameters of 3.0T MRI scanner were:TR 2550-2675ms, TE 21.0ms, slice thick 3.0mm, distance0-0.1mm, FOV (24×24 mm)-(201×230mm). The parameters of 1.5T MRI scanner were:TR 440-450.0ms, TE 14.0-16.0ms, slice thick 3.0mm, distance 0-0.1mm, FOV (24mm×24mm)-(193×220mm)The hyper-intensity of posterior pituitary was absent in 19cases, with the significant hypo-intensity in 6 cases. There are 8 cases with purely disappearance of the high signal in normal saddle area,6 cases with thickening of the pituitary stalk,2 cases with vacuole turkish saddle,1 case with nodule within the pituitary stalk,1 case with dysplasia of pituitary gland and 1 cases with pituitary microadenoma.1. MRI has the high resolution on saddle area. The changes (such as the thickening, disruption and migration of the pituitary stalk, the disappearance of the high signal intensity of the posterior pituitary lobe) can be seen clearly.2. The high signal intensity of the posterior pituitary lobe disappears in CDI. It indicates the dysfunction of the hypothalamus-pituitary axis. It is the non-specific indicators of CDI. SO it must be given high consideration to exclude CDI.3. For the newly diagnosed patients, it should be tried to do the thin and enhanced MR scanning on the saddle area. It should not be given up the follow-up visit when there is no definite causes in the initial stage. The regular examinations of the images and the pituitary function are important. They are the key point to make the right diagnosis and treatment.
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