Intraoperative MRI successfully predicts newly diagnosed supratentorial glioblastoma: Study

High-grade gliomas (HGGs) continue to carry poor prognoses, and patient outcomes depend heavily on the extent of resection (EOR). The utility of conventional image-guided surgery is limited by intraoperative brain shift. More recent techniques to maximize EOR, including intraoperative imaging and the use of fluorescent dyes, combat these limitations. However, the relative efficacy of these two techniques has never been systematically compared. There is rising evidence that in glioblastoma (GBM) surgery an increase of extent of resection (EoR) leads to an increase in patient survival. Intraoperative MRI (iMRI) is used in the surgical treatment of glioblastoma, with uncertain effects on outcomes.

Thus, Amar S Shah and colleagues carried out the present study to evaluate the impact of iMRI on the extent of resection (EOR) and overall survival (OS) while controlling for other known and suspected predictors.

They studied a total of 640 adult patients included in a multicenter retrospective cohort study. All patients were newly diagnosed with supratentorial glioblastoma who underwent resection. iMRI was performed in 332/640 cases (51.9%). Reviews of MRI features and tumor volumetric analysis were performed on a subsample of cases (n = 286; 110 non-iMRI, 176 iMRI) from a single institution.

Shah observed the following results from his study-

a. Gross-total resection (GTR) was achieved in 403/640 cases (63.0%).

b. Kaplan-Meier analysis of 286 cases with volumetric analysis for EOR showed longer OS for 100% EOR compared to all other groups.

c. Additional resection after iMRI was performed in 104/122 cases (85.2%) with an initial subtotal resection (STR), leading to a 6.3% mean increase in EOR and a 2.2-cm3 mean decrease in tumor volume.

d. For iMRI cases with volumetric analysis, the GTR rate increased from 54/176 (30.7%) on iMRI to 126/176 (71.5%) postoperatively.

e. The EOR was significantly higher in the iMRI group for intended GTR and STR groups.

f. Predictors of GTR on multivariate logistic regression included iMRI use and intended GTR.

g. Predictors of shorter OS on multivariate Cox regression included older age, STR, isocitrate dehydrogenase 1 (IDH1) wild type, no O6-methylguanine DNA methyltransferase (MGMT) methylation, and no Stupp therapy.

h. iMRI was a significant predictor of OS on univariate (HR 0.82, 95% CI 0.69-0.98; p = 0.03) but not multivariate analyses.

i. Use of iMRI was not associated with an increased rate of new permanent neurological deficits.

Therefore, they concluded that "GTR increased OS for patients with newly diagnosed glioblastoma after adjusting for other prognostic factors. iMRI increased EOR and GTR rate and was a significant predictor of GTR on multivariate analysis; however, iMRI was not an independent predictor of OS."

Additional supporting evidence is needed to determine the clinical benefit of iMRI in the management of glioblastoma, Shah further added.

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Shah AS, Sylvester PT, Yahanda AT, Vellimana AK, Dunn GP, Evans J, Rich KM, Dowling JL, Leuthardt EC, Dacey RG, Kim AH, Grubb RL, Zipfel GJ, Oswood M, Jensen RL, Sutherland GR, Cahill DP, Abram SR, Honeycutt J, Shah M, Tao Y, Chicoine MR. Intraoperative MRI for newly diagnosed supratentorial glioblastoma: a multicenter-registry comparative study to conventional surgery. J Neurosurg. 2020 Oct 9:1-10. doi: 10.3171/2020.6.JNS19287. Epub ahead of print. PMID: 33035996.