Comparing MRI volume measurement techniques for pituitary macroadenoma: Investigating volume reduction and its relationship with biochemical control

Pituitary adenomas are one of the most common types of primary intracranial tumors. Measuring pituitary adenoma volume is fundamental for effective management. This study aimed to assess the reliability of the ellipsoid method in comparison with the perimeter method for measuring pituitary macroadenoma volume. In addition, we investigated the correlation between adenoma size reduction and biochemical control in functioning adenomas. This was a retrospective cross-sectional cohort study including 113 patients with pituitary macroadenomas. MRI was obtained for volume measurement by ellipsoid and perimeter methods using two types of DICOM viewer software. Both ellipsoid and perimeter methods exhibit positive, strong, and significant correlations in pituitary macroadenomas in pre-treatment and post-treatment volume (Spearman correlation coefficient 0.95, p-value <0.0001). There was no significant difference in the mean post-treatment pituitary adenoma volume measurements utilizing the ellipsoid and the perimeter methods in different treatment modalities. There were significant differences in the pre-treatment volume measurements between the two methods, both in NFPA and prolactinoma. No correlation was found between volume variability measured by ellipsoid and perimeter methods and the degree of hormonal control in functioning pituitary adenomas. Both the ellipsoid and perimetric methods can be utilized for pituitary adenoma volume measurements as they demonstrate a strong and positive correlation. However, it is important to note that the ellipsoid method tends to result in overestimated tumor volume. There was no correlation between the adenoma size reduction and the degree of biochemical response in functioning adenomas.