Magnetic Resonance Imaging Determination of Normal Pituitary Gland Dimensions in Zaria, Northwest Nigerian Population

Objectives: To determine the dimensions of normal pituitary gland using T1-weighted magnetic resonance images (MRI) and to determine their relationship with age and sex. Materials and Methods: Cranial MRI scans of 100 individuals with clinically normal pituitary function (58 males and 42 females) and in the age range 14-82 years were reviewed in order to obtain volumetric measurements of the pituitary gland. The height, width, and depth of the pituitary were obtained from mid-sagittal and coronal planes, while the volume was calculated from these measured parameters. The data obtained were stratified based on age and sex for analysis. Statistical tests applied included Students t-test and Pearson correlation. A minimum level of statistical significance was set at P < 0.05. Results: The mean pituitary volumes were 334.1 +/- 145.8 mm(3) and 328.1 +/- 129.2 mm(3) while the mean pituitary heights were 6.45 +/- 1.7 mm and 6.46 +/- 1.57 mm in males and females, respectively. Although there was no statistically significant difference between pituitary height and pituitary volume in both sexes, they correlated negatively with increasing age (r = -202, P = 0.04 and r = -410, P = 0.000, respectively). Both parameters were highest in pubertal subjects and declined steadily with age, with a second peak occurring only for pituitary height in the sixth decade. The mean pituitary widths (9.08 +/- 2.59 mm and 9.21 +/- 1.86 mm) and depths (10.59 +/- 1.71 mm and 10.49 +/- 1.57 mm) in males and females, respectively, did not show remarkable changes with age and sex in the individuals studied. Conclusion: With this study, we have provided reference values in Nigerian population for the dimensions of normal pituitary gland, in order to facilitate assessment and diagnosis in patients with abnormalities of the hypothalamic-pituitary axis.