Magnetic resonance imaging-based morphometric differences in the normal pituitary gland with functional and...

Pituitary adenomas (PAs) are common intracranial neoplasms classified as hormone-secreting or nonfunctional. Nonfunctional PAs (NFPAs) typically present at larger sizes and exert greater mass effect on surrounding structures, including the pituitary gland (PG) and pituitary stalk (PS). However, morphological changes of the PG and PS in the presence of PAs remain incompletely characterized.

A retrospective study of 225 patients (142 NFPAs, 83 hormone-secreting PAs) was performed using 1.5T and 3T magnetic resonance imaging. PG and PS measurements were compared using Welch's t-test. Tumor classification analyses were conducted with Welch's analysis of variance and Fisher's exact tests.

NFPAs were significantly larger than hormone-secreting tumors across all dimensions, including height, anterior-posterior width, transverse diameter, and volume (p < 0.05). In contrast, maximum anterior-posterior PG width, transverse diameter, and PG volume were significantly greater in hormone-secreting tumors (p = 0.026, p = 0.049, p < 0.0001). Other PG and PS parameters showed no significant differences. Among tumor subtypes, PS maximum transverse diameter was the only parameter that significantly differed (p < 0.001). Carotid encasement (p = 0.0186), suprasellar extension (p = 0.0002), and PG/PS compression (p = 0.0164) were also associated with tumor classification.

NFPAs demonstrate larger tumor burden and greater mass effect, whereas hormone-secreting tumors are associated with relatively preserved PG morphology. PS structural changes are limited, with transverse diameter emerging as the primary distinguishing feature. These findings may improve preoperative imaging assessment and surgical planning.