Objective  To summarize the magnetic resonance imaging (MRI) features of sella after transsphenoidal resection of pituitary macroadenoma, and explore the rational opportunities for the first radiological follow-up.

  Methods  The clinical data and preoperative and postoperative MRI of 40 patients with macroadenoma were retrospectively analysed. The postoperative MRI was performed at early period (within 1 week), medium period (about 3 month), or later period (after 6 months or 1 year).

  Results  Patients were divided into two groups based on preoperative data:invasive macroadenoma group (n=16) and noninvasive macroadenoma group (n=24). Residual tumors (n=11) were only found in the invasive macroadenoma group during the radiological follow-up. During the early period of postoperative follow-up, pituitary mass can still be found in soft tissue, with the heights decreased in varying degrees compared with those of the preoperative mass. The implanted material showed no enhancement on post-contrast MRI. The residural tumors showed mild to middle enhancement, while the residual pituitary gland showed apperent enhancement. During the medium period of postoperative follow-up, the implanted material was obviously or completely absorbed; the pituitary glands often collapsed, while the residual pituitary glands showed remarked enhancement. The re-expansion of the gland was found in some cases. The residural tumors were shown clearly, and the visibility of these residural tumors were not apparently different from those in the early period. The MRI features in the later were similar to those in the medium period. The inflammation of sphenoid sinus were absorbed slowely, and was still present after 6 months after surgery in most cases. Tumor recurrences were found in three patients one year later after the surgury, shown as the increased residural tumors (n=2), and newly developed soft tissue (n=1).

  Conclusions  The MRI features differ at different time points after transsphenoidal resection of pituitary macroadenoma. For noninvasive macroadenoma, an MRI follow-up 3 months after surgery was appropriate and sufficient. For invasive macroadenoma, however, postoperative residual tumors may be found during early-and medium-period followup.