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At least 127 records · Page 7Linked to original sources

Posterior pituitary gland: appearance on MR images in normal and pathologic states.

T1-weighted magnetic resonance (MR) images of the pituitary gland and sella turcica routinely demonstrate a region of high signal intensity in the neurohypophysis. High-resolution MR imaging studies of the sella turcica in 200 subjects with a normal or abnormal sella were analyzed. The hyperintensity was found in the images of about 90% of healthy subjects and patients with microadenoma, in only 43% of patients with macroadenoma, and in 12% of patients with empty sellae. The signal was absent in several patients with functional or anatomic abnormalities of the hypothalamic-hypophyseal axis. It is concluded that the high signal intensity in the posterior lobe of the pituitary gland is present in most healthy individuals and that its absence in many patients with large intrasellar masses and empty sellae is due to compression of posterior lobe tissue. Its absence in diabetes insipidus further suggests a relationship between hyperintensity and the functional status of the hypothalamic-hypophyseal axis.

Adenoma↗

Contrast enhanced area of posterior pituitary gland in early dynamic MRI exceeds hyperintense area on T1-weighted images.

Seventeen normal pituitary glands were studied by midline sagittal (and in one case axial) dynamic MRI before and immediately after injection of Gd-DTPA, using spin-echo sequences with a short repetition time. Images were obtained at 1 min intervals for 6 min at 1.5 T. A well-defined focal area with marked enhancement was seen in the posterior portion of the pituitary gland on the first image after injection of Gd-DTPA. The size of the early enhancing area in the posterior pituitary (EEPP) was compared with the high signal of the posterior pituitary (HSPP) on the precontrast image. The EEPP was larger than the HSPP in 10 cases (59%). The two were equal in size in seven cases (41%). The EEPP was anteriorly convex in 11 cases (65%), whereas HSPP was anteriorly convex in 4 cases (24%). We believe that EEPP closely represents the real extent of the posterior lobe. Our results support the hypothesis that HSPP may involve only a portion of the posterior pituitary.

Contrast Media↗

Congenital hypopituitarism with hypoplasia of the anterior pituitary gland and a normal posterior pituitary lobe.

We report a female infant with congenital hypopituitarism. All anterior pituitary hormones were deficient, and the anterior pituitary gland was undetectable on magnetic resonance images. Antidiuretic hormone secretion was appropriate, and the posterior lobe was localized at the end of the stalk, in the sella. These observations suggest that the posterior pituitary gland may develop independently of the anterior lobe.

Female↗

Delayed lymphocytic infundibuloneurohypophysitis following successful transsphenoidal treatment of Cushing's disease.

Lymphocytic infundibuloneurohypophysitis is a rare disorder in which neurohypophyseal function is impaired by an autoimmune process. Although several etiologies for this rare entity have been suggested, its occurrence following transsphenoidal adenomectomy has not been reported. A 20-year-old man presented with diabetes insipidus - seven years after successful transsphenoidal microadenomectomy for Cushing's disease, first diagnosed at the age of 13. Seven years later, he developed fairly rapid onset of polydipsia and polyuria. Magnetic resonance imaging demonstrated swelling of the posterior pituitary gland with thickening of the pituitary stalk. Endocrinological evaluation revealed neurohypophyseal dysfunction without the adenohypophysis being affected. On the basis of these findings, a diagnosis of lymphocytic infundibuloneurohypophysitis was made. The mass lesion of the posterior pituitary resolved after the administration of corticosteroids for two months and no operation was required. Lymphocytic infundibuloneurohypophysitis should be considered in the differential diagnosis of pituitary mass lesions following transsphenoidal surgery, especially when the mass is confined to the posterior pituitary gland with neurohypophyseal function being compromised.

Adenoma↗

Serial MR intensity changes of the posterior pituitary in patients with diabetes insipidus after transsphenoidal surgery for pituitary adenomas: report of two cases.

This is the first report describing magnetic resonance (MR) intensity changes of the posterior pituitary gland in the patients suffering from the classical "triphasic" diabetes insipidus (DI) after transsphenoidal surgery for pituitary adenomas. A 21-year-old female and a 54-year-old female were admitted to our hospital with the diagnosis of Cushing's disease and acromegaly due to pituitary microadenomas, respectively. No evidence of DI was found, and T1-weighted MR images exhibited "bright spot" corresponding to the posterior pituitary in both cases. Both experienced the classical "triphasic" pattern of water metabolism disturbance after successful transsphenoidal resection of pituitary adenomas, that is, polyuria-oliguria-polyuria. The MR signal hyperintensity in posterior pituitary was detected during the first polyuric phase, but the hyperintensity disappeared during the second polyuric phase. In addition, "bright spot" was restored along with the recovery from DI in the chronic phase. These findings of serial MR images supported that the first DI phase of the classical triphasic course of water metabolism disturbance was caused by secretional dysfunction of stored vasopressin from the posterior gland, whereas the second DI phase was due to impairment in the functional integrity producing vasopressin-containing granules after depletion of vasopressin in the oliguric phase.

Adenoma↗

Hypopituitarism and stalk agenesis: a congenital syndrome worsened by breech delivery?

Thirty-seven patients with idiopathic hypopituitarism, of whom 12 had multiple pituitary hormone deficiencies (MPHD) and 25 isolated growth hormone deficiency (IGHD), were evaluated by magnetic resonance imaging (MRI). Twenty-two of the 37 showed congenital anterior pituitary hypoplasia, stalk agenesis and ectopic posterior pituitary gland at the infundibular recess (group A), while the remaining 15 presented isolated anterior pituitary hypoplasia (group B). Perinatal histories obtained from all patients demonstrated that 18/22 children of group A (81.81%) had histories of adverse perinatal events, with breech presentation in 15 (68.18%). Twelve of 12 children of group A born by breech delivery developed MPHD; 3 born by cesarean section for breech presentation had only IGHD. Patients of group B had also a high incidence of perinatal insults (12/15, 80%), but breech delivery was markedly less frequent (13.33 vs. 68.18% of group A) and responsible for only IGHD. Group B had also higher percentages of maternal spontaneous abortion and low birth weight. Our study suggests that several factors may play a role in the development of growth hormone deficiency. Some patients had severe perinatal insults apparently leading to hypopituitarism. We were able to define by MRI a group of patients with congenital abnormalities, such as anterior pituitary hypoplasia, stalk agenesis and posterior pituitary ectopia, among whom breech presentation was very common. In this group, breech delivery was always followed by MPHD while cesarean or normal delivery in such patients was followed by IGHD only.

Adult↗