Intraoperative MR imaging increases the extent of tumor resection in patients with high-grade gliomas

Abstract

Background and purpose: MR is being used increasingly as an intraoperative imaging technique. The purpose of this study was to test the hypothesis that intraoperative MR imaging increases the extent of tumor resection, thus improving surgical results in patients with high-grade gliomas.

Methods: Thirty-eight patients with intracranial high-grade gliomas underwent 41 operations. Using a neuronavigation system, tumors were resected in all patients to the point at which the neurosurgeon would have terminated the operation because he thought that all enhancing tumor had been removed. Intraoperative MR imaging (0.2 T) was performed, and surgery, if necessary and feasible, was continued. All patients underwent early postoperative MR imaging (1.5 T). By comparing the proportions of patients in whom complete resection of all enhancing tumor was shown by intraoperative and early postoperative MR imaging, respectively, the impact of intraoperative MR imaging on surgery was determined.

Results: Intraoperative MR imaging showed residual enhancing tumor in 22 cases (53.7%). In 15 patients (36.6%), no residual tumor was seen, whereas the results of the remaining four intraoperative MR examinations (9.7%) were inconclusive. In 17 of the 22 cases in which residual tumor was seen, surgery was continued. Early postoperative MR imaging showed residual tumor in eight patients (19.5%) and no residual tumor in 31 cases (75.6%); findings were uncertain in two patients (4.9%). The difference in the proportion of "complete removals" was statistically highly significant (P = .0004).

Conclusion: Intraoperative MR imaging significantly increases the rate of complete tumor removal. The rate of complete removal of all enhancing tumor parts was only 36.6% when neuronavigation alone was used, which suggests the benefits of intraoperative imaging.

fig 1.

Surgically induced enhancement in the “uncertain” case of a 45-year-old man with a glioblastoma multiforme. The tumor is above the level of these T1-weighted images. Left, Preoperative MR image (674/20/2) does not show enhancement in the head of the right caudate nucleus. Problems with hemostasis necessitated repeated electrocoagulations in this region. Middle, Intraoperative MR image (532/15/3) shows partially solid-appearing contrast enhancement of the head of the caudate nucleus. A small biopsy was obtained from this region and did not show residual tumor histologically. Surgery was terminated. Right, Early postoperative MR image (674/20/2) does not show persistent enhancement of the head of the caudate nucleus. The intraoperative enhancement probably represented transient blood-brain barrier disruption.

fig 2.

A 41-year-old woman with a recurrent glioblastoma multiforme. Left, Preoperative T1-weighted image shows a left-hemispheric lesion (674/20/2). Middle, Intraoperative MR image (532/15/3) shows residual enhancing tumor (arrowhead). Right, Surgery was continued, and the residual tumor was removed, as shown in this early postoperative MR image (674/20/2).

fig 3.

A 55-year-old man with a glioblastoma multiforme. The bulk of the tumor is above the level of these T1-weighted images. Left, Preoperative MR image shows a right-hemispheric lesion (674/20/2). Middle, Intraoperative MR image (532/15/3) shows residual tumor at the bottom of the resection cavity (arrowhead). Right, Surgery was continued, and this residual tumor was removed, as shown in this early postoperative MR image (674/20/2).

fig 4.

“Failure” of the intraoperative MR imaging approach in a 46-year-old man with an anaplastic glioma. Left, Preoperative MR image shows a right-hemispheric lesion (674/20/2). Middle, Intraoperative MR image (532/15/3) shows massive residual tumor. Surgery was continued with extensive further tumor resection. Right, Early postoperative MR image (674/20/2), however, still shows residual enhancing tumor (arrowheads).