PITUITARY MAGNETIC-RESONANCE-IMAGING IN NORMAL HUMAN VOLUNTEERS - OCCULT ADENOMAS IN THE GENERAL-POPULATION

Objective: To determine the prevalence of focal lesions of the pituita ry gland that suggest the presence of a pituitary adenoma in asymptoma tic persons. Design: 100 normal volunteers (70 women, 30 men; age rang e, 18 to 60 years old) were studied by high-resolution magnetic resona nce imaging (MRI) of the pituitary gland before and after administrati on of gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA). Setting : Occult pituitary adenomas are identified at autopsy in 3% to 27% of unselected asymptomatic patients. The frequency of incidental pituitar y adenomas detected by MRI in normal persons is unknown. Measurements: The MRI scans from volunteers were randomly mixed with scans of 57 pa tients with Cushing disease and interpreted independently by three bli nded reviewers. Results: Seven women (10%) and three men (10%) had foc al areas of decreased signal intensity in the pituitary gland after ad ministration of Gd-DTPA. The lesions ranged from 3 to 6 mm in greatest diameter and were diagnosed as pituitary adenomas by at least two of the three reviewers. When similar lesions were detected on MRI scans i n patients with Cushing disease, the positive predictive value for ide ntification of an adenoma at that site was 86%. Conclusions: About 10% of the normal adult population have pituitary abnormalities on MRI sc ans that are compatible with the diagnosis of asymptomatic pituitary a denomas. Most pituitary adenomas remain asymptomatic and do not requir e treatment.