MR IMAGING AND EVALUATION OF THE PITUITARY STALK: SIZE, SHAPE, AND ENHANCEMENT PATTERN

Background: Knowing the normal imaging appearance of the pituitary stalk is essential for diagnosing pituitary infundibular lesions and a more accurate assessment of the stalk. 

Objective: We aimed to evaluate the normal pituitary stalk using high-resolution magnetic resonance imaging(MRI) at 1.5T.

Materials and Methods: All images were obtained with a 1.5 T MR scanner using a dedicated pituitary MRI protocol. A total of 50 patients, with a gender distribution of 32 men and 18 women, were included in the study. Their ages ranged from 18 to 70 years, averaging 43 years. The diameter and length of the pituitary stalk were measured. The signal intensity and enhancement of the stalk were visually evaluated on pre- and post-contrast T1-weighted images.

Results: The average anterior-posterior (AP) and transverse diameters of the pituitary stalk at the optic chiasm level were 3.19 ± 0.48 mm and 3.25 ± 0.46 mm, respectively. The average AP and transverse diameters of the pituitary stalk at the pituitary gland insertion were 1.93 ± 0.38 mm and 1.95 ± 0.40 mm, respectively. The length of the pituitary stalk was 6.35 ± 1.63 mm. Compared to the optic chiasm and neurohypophysis,the stalk demonstrated hypointensity on unenhancedMR images. The enhancement of the pituitary stalk is observed in all cases. 

Conclusions: The study pinpointed key MRI criteria for evaluating the normal pituitary stalks size, shape, and how it takes up contrast dye. These details act as a roadmap for spotting and understanding pituitary gland issues.