Background and purpose: Although there have been several reports on postoperative MR imaging of the sella, immediate postoperative changes (usually within 3 days) have not been extensively analyzed. The purpose of this study was to establish the value of early postoperative MR imaging in differentiating residual tumor from postoperative surgical changes in the sella after transsphenoidal resection of pituitary adenomas.
Methods: Eighty-three patients with surgically proven pituitary adenomas (32 nonfunctioning, 24 prolactin-secreting, 22 growth hormone-secreting, and five prolactin- and growth hormone-secreting tumors) were studied prospectively. All patients underwent dynamic MR imaging within 7 days after surgery. We analyzed the postoperative MR images by focusing on changes in the pituitary gland, signal intensity, resorption of implanted material, and visibility of residual tumor. The patients were divided into four groups according to enhancement pattern of the postoperative pituitary mass: no enhancement, nodular enhancement, peripheral rim enhancement, and a combination of nodular and peripheral rim enhancement.
Results: Postoperative changes included resorption of implanted material and reexpansion of the pituitary gland. In 22 patients, residual tumors were found, and all patients showed nodular or combined enhancement. The residual tumors were confirmed by immediate reoperation in three patients, by hormonal assay and follow-up MR images in 11 patients with functioning adenomas, and by growth of the tumor on follow-up MR images in eight patients with nonfunctioning adenomas. Forty-eight patients showed no enhancement and 13 patients showed peripheral rim enhancement.
Conclusion: Early postoperative dynamic MR imaging after transsphenoidal resection in pituitary adenoma is very effective in differentiating residual tumor from postoperative surgical changes.