Fig. 2. Examples of postoperative changes in the residual tumor on serial MRIs. Preoperative (A), immediate postoperative (B), and 6-month postoperative (C) T-1 weighted contrast-enhanced MRI of right VS. The thin tumor capsule covering the facial nerve was left during the surgery (white arrowhead). Postoperative image taken at 6 months showing progressive closure of the tumorectomy cavity, and the residual tumor was changed to a shape more suitable for gamma knife radiosurgery (white arrow). Preoperative (D), immediate postoperative (E), and 6-month postoperative (F) MRI of left VS. The residual tumor (black arrow) left around the porus acusticus was observed on 6-month postoperative images, but it was not visualized on immediate postoperative imaging.

MRI = magnetic resonance imaging, VS = vestibular schwannoma.