MRI Of Pituitary Hyperplasia In Primary Hypothyroidism

Purpose:To analyze the MRI features of pituitary hyperplasia in primary hypothyroidism,and to discuss the differential diagnosis between the hyperplasia of the pituitary gland and the other intrasellar mass such as pituitary adenoma.Methods and Materials:The MRI plan scan and enhanced scan were performed in 32 patients who were confirmed to be primary hypothyroidism by the clinical manifestations and the laboratory examinations.Analyze the MRI features of pituitary disorders;include the shape,height,signal,pituitary stalk and the adjacent structures. After thyroid hormone replacement therapy,follow-up MRI and the laboratory examinations were performed in first and the third month.We contrasted the MRI features of the pre-therapy and post-therapy to find the change of the pituitary disorders.3 patients were operated as adenoma and confirmed by pathology.Results:The patients were mostly young females(71.88%of the patients were child and young persons below 30 years old,male:female =7:1),range from 5 years old to 74 years old with average 25.81±17.79 years old.The most common cause of hypothyroidism in this group was autoimmune thyroiditis.The course of the disease was range from half year to 21 years.The laboratory examinations showed that the serum TSH level increased and the serum T3,T4 levels decreased.Additionally some patients' serum PRL level increased.The pituitary MRI showed that all the patients' pituitary glands enlarged in different degrees,the highest is about 18mm.The signals of the masses were all homogeneous with markedly enhancement.The stalks were not shifted except only one patient even some were pressed markedly.After thyroid hormone replacement therapy,the follow-up MRI demonstrated that the enlarged glands mostly became normal.The heights of the pituitary glands were revealed a significant difference between the pre-therapy and post-therapy(P＜0.05).Conclusion:1.Primary hypothyroidism may present intrasellar mass secondary to hyperplasia of the pituitary gland.2.Hyperplasia of the pituitary gland in primary hypothyroidism has typical MRI features.3.MRI can offer the information of the pituitary gland and its adjacent structures to distinguish the hyperplasia of the pituitary gland from the other intrasellar mass such as pituitary adenoma.4.After thyroid hormone replacement therapy,the follow-up MRI demonstrated that the enlarged glands mostly became normal.The heights of the pituitary glands were revealed a significant difference between the pre-therapy and post-therapy.5.MRI is the utility choice to demonstrate pituitary hyperplasia in primary hypothyroidism. Radiologists should be aware of this entity,since the condition responds to medical treatment and the patients may be spared unnecessary surgery.