Intraoperative MRI for newly diagnosed supratentorial glioblastoma: a multicenter-registry comparative study to conventional surgery.

OBJECTIVE: Intraoperative MRI (iMRI) is used in the surgical treatment of glioblastoma, with uncertain effects on outcomes. The authors evaluated the impact of iMRI on extent of resection (EOR) and overall survival (OS) while controlling for other known and suspected predictors. METHODS: A multicenter retrospective cohort of 640 adult patients with newly diagnosed supratentorial glioblastoma who underwent resection was evaluated. 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. RESULTS: The median age was 60.0 years (mean 58.5 years, range 20.5-86.3 years). The median OS was 17.0 months (95% CI 15.6-18.4 months). Gross-total resection (GTR) was achieved in 403/640 cases (63.0%). Kaplan-Meier analysis of 286 cases with volumetric analysis for EOR (grouped into 100%, 95%-99%, 80%-94%, and 50%-79%) showed longer OS for 100% EOR compared to all other groups (p < 0.01). Additional resection after iMRI was performed in 104/122 cases (85.2%) with initial subtotal resection (STR), leading to a 6.3% mean increase in EOR and a 2.2-cm3 mean decrease in tumor volume. For iMRI cases with volumetric analysis, the GTR rate increased from 54/176 (30.7%) on iMRI to 126/176 (71.5%) postoperatively. The EOR was significantly higher in the iMRI group for intended GTR and STR groups (p = 0.02 and p < 0.01, respectively). Predictors of GTR on multivariate logistic regression included iMRI use and intended GTR. 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. 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. Use of iMRI was not associated with an increased rate of new permanent neurological deficits. CONCLUSIONS: 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.

Using Histopathology to Assess the Reliability of Intraoperative Magnetic Resonance Imaging in Guiding Additional Brain Tumor Resection: A Multicenter Study.

BACKGROUND: Intraoperative magnetic resonance imaging (iMRI) is a powerful tool for guiding brain tumor resections, provided that it accurately discerns residual tumor. OBJECTIVE: To use histopathology to assess how reliably iMRI may discern additional tumor for a variety of tumor types, independent of the indications for iMRI. METHODS: A multicenter database was used to calculate the odds of additional resection during the same surgical session for grade I to IV gliomas and pituitary adenomas. The reliability of iMRI for identifying residual tumor was assessed using histopathology of tissue resected after iMRI. RESULTS: Gliomas (904/1517 cases, 59.6%) were more likely than pituitary adenomas (176/515, 34.2%) to receive additional resection after iMRI (P < .001), but these tumors were equally likely to have additional tissue sent for histopathology (398/904, 44.4% vs 66/176, 37.5%; P = .11). Tissue samples were available for resections after iMRI for 464 cases, with 415 (89.4%) positive for tumor. Additional resections after iMRI for gliomas (361/398, 90.7%) were more likely to yield additional tumor compared to pituitary adenomas (54/66, 81.8%) (P = .03). There were no significant differences in resection after iMRI yielding histopathologically positive tumor between grade I (58/65 cases, 89.2%; referent), grade II (82/92, 89.1%) (P = .98), grade III (72/81, 88.9%) (P = .95), or grade IV gliomas (149/160, 93.1%) (P = .33). Additional resection for previously resected tumors (122/135 cases, 90.4%) was equally likely to yield histopathologically confirmed tumor compared to newly-diagnosed tumors (293/329, 89.0%) (P = .83). CONCLUSION: Histopathological analysis of tissue resected after use of iMRI for grade I to IV gliomas and pituitary adenomas demonstrates that iMRI is highly reliable for identifying residual tumor.

Impact of 3-Dimensional Versus 2-Dimensional Image Distortion Correction on Stereotactic Neurosurgical Navigation Image Fusion Reliability for Images Acquired With Intraoperative Magnetic Resonance Imaging.

BACKGROUND: Fusion of preoperative and intraoperative magnetic resonance imaging (iMRI) studies during stereotactic navigation may be very useful for procedures such as tumor resections but can be subject to error because of image distortion. OBJECTIVE: To assess the impact of 3-dimensional (3D) vs 2-dimensional (2D) image distortion correction on the accuracy of auto-merge image fusion for stereotactic neurosurgical images acquired with iMRI using a head phantom in different surgical positions. METHODS: T1-weighted intraoperative images of the head phantom were obtained using 1.5T iMRI. Images were postprocessed with 2D and 3D image distortion correction. These studies were fused to T1-weighted preoperative MRI studies performed on a 1.5T diagnostic MRI. The reliability of the auto-merge fusion of these images for 2D and 3D correction techniques was assessed both manually using the stereotactic navigation system and via image analysis software. RESULTS: Eight surgical positions of the head phantom were imaged with iMRI. Greater image distortion occurred with increased distance from isocenter in all 3 axes, reducing accuracy of image fusion to preoperative images. Visually reliable image fusions were accomplished in 2/8 surgical positions using 2D distortion correction and 5/8 using 3D correction. Three-dimensional correction yielded superior image registration quality as defined by higher maximum mutual information values, with improvements ranging between 2.3% and 14.3% over 2D correction. CONCLUSION: Using 3D distortion correction enhanced the reliability of surgical navigation auto-merge fusion of phantom images acquired with iMRI across a wider range of head positions and may improve the accuracy of stereotactic navigation using iMRI images.

Initial Experience Using Intraoperative Magnetic Resonance Imaging During a Trans-Sulcal Tubular Retractor Approach for the Resection of Deep-Seated Brain Tumors: A Case Series.

BACKGROUND: Treatment of deep-seated subcortical intrinsic brain tumors remains challenging and may be improved with trans-sulcal tubular brain retraction techniques coupled with intraoperative magnetic resonance imaging (iMRI). OBJECTIVE: To conduct a preliminary assessment of feasibility and efficacy of iMRI in tubular retractor-guided resections of intrinsic brain tumors. METHODS: Assessment of this technique and impact upon outcomes were assessed in a preliminary series of brain tumor patients from 2 centers. RESULTS: Ten patients underwent resection with a tubular retractor system and iMRI. Mean age was 53.2 ± 9.0 yr (range: 37-61 yr, 80% male). Lesions included 6 gliomas (3 glioblastomas, 1 recurrent anaplastic astrocytoma, and 2 low-grade gliomas) and 4 brain metastases (1 renal cell, 1 breast, 1 lung, and 1 melanoma). Mean maximal tumor diameter was 2.9 ± 0.95 cm (range 1.2-4.3 cm). The iMRI demonstrated subtotal resection (STR) in 6 of 10 cases (60%); additional resection was performed in 5 of 6 cases (83%), reducing STR rate to 2 of 10 cases (20%), with both having tumor encroaching on eloquent structures. Seven patients (70%) were stable or improved neurologically immediately postoperatively. Three patients (30%) had new postoperative neurological deficits, 2 of which were transient. Average hospital length of stay was 3.4 ± 2.0 d (range: 1-7 d). CONCLUSION: Combining iMRI with tubular brain retraction techniques is feasible and may improve the extent of resection of deep-seated intrinsic brain tumors that are incompletely visualized with the smaller surgical exposure of tubular retractors.

Endovascular management of internal carotid artery injuries secondary to endonasal surgery: case series and review of the literature.

OBJECTIVE Internal carotid artery (ICA) injury is a rare but severe complication of endonasal surgery. The authors describe their endovascular experience managing ICA injuries after transsphenoidal surgery; they review and summarize the current literature regarding endovascular techniques; and they propose a treatment algorithm based on the available evidence. METHODS A retrospective review of 576 transsphenoidal pituitary adenoma resections was performed. Cases of ICA injury occurring at our institution and transfers from other hospitals were evaluated. Endovascular treatments for ICA injury reported in the literature were also reviewed and summarized. RESULTS Seven cases were identified from the institutional cohort (mean age 46.3 years, mean follow-up 43.4 months [1-107 months]) that received endovascular treatment for ICA injury. Five injuries occurred at our institution (5 [0.9%] of 576), and 2 injuries occurred at outside hospitals. Three patients underwent ICA sacrifice by coil placement, 2 underwent lesion embolization (coil or stent-assisted coil placement), and 2 underwent endoluminal reconstruction (both with flow diversion devices). Review of the literature identified 98 cases of ICA injury treated with endovascular methods. Of the 105 total cases, 46 patients underwent ICA sacrifice, 28 underwent lesion embolization, and 31 underwent endoluminal reconstruction. Sacrifice of the ICA proved a durable solution in all cases; however, the rate of persistent neurological complications was relatively high (10 [21.7%] of 46). Lesion embolization was primarily performed by coil embolization without stenting (16 cases) and stent-assisted coiling (9 cases). Both techniques had a relatively high rate of at least some technical complication (6 [37.5%] of 16 and 5 [55.6%] of 9, respectively) and major technical complications (i.e., injury, new neurological deficit, or ICA sacrifice) (5 [31.3%] of 16 and 2 [22.2%] of 9, respectively). Endoluminal reconstruction was performed by covered stent (24 cases) and flow diverter (5 cases) placement. Covered stents showed a reasonably high rate of technical complications (10 [41.7%] of 24); however, 8 of these problems were resolved, leaving a small percentage with major technical complications (2 [8.3%] of 24). Flow diverter placement was also well tolerated, with only 1 minor technical complication. CONCLUSIONS Endovascular treatments including vessel sacrifice, coil embolization (with or without stent assistance), and endoluminal reconstruction offer a tailored approach to ICA injury management after endonasal surgery. Vessel sacrifice remains the definitive treatment for acute, uncontrolled bleeding; however, vessel preservation techniques should be considered carefully in select patients. Multiple factors including vascular anatomy, injury characteristics, and risk of dual antiplatelet therapy should guide best treatment, but more study is needed (particularly with flow diverters) to refine this decision-making process. Ideally, all endovascular treatment options should be available at institutions performing endonasal surgery.

Combined high-field intraoperative magnetic resonance imaging and endoscopy increase extent of resection and progression-free survival for pituitary adenomas.

PURPOSE: The clinical benefit of combined intraoperative magnetic resonance imaging (iMRI) and endoscopy for transsphenoidal pituitary adenoma resection has not been completely characterized. This study assessed the impact of microscopy, endoscopy, and/or iMRI on progression-free survival, extent of resection status (gross-, near-, and sub-total resection), and operative complications. METHODS: Retrospective analyses were performed on 446 transsphenoidal pituitary adenoma surgeries at a single institution between 1998 and 2012. Multivariate analyses were used to control for baseline characteristics, differences during extent of resection status, and progression-free survival analysis. RESULTS: Additional surgery was performed after iMRI in 56/156 cases (35.9%), which led to increased extent of resection status in 15/156 cases (9.6%). Multivariate ordinal logistic regression revealed no increase in extent of resection status following iMRI or endoscopy alone; however, combining these modalities increased extent of resection status (odds ratio 2.05, 95% CI 1.21-3.46) compared to conventional transsphenoidal microsurgery. Multivariate Cox regression revealed that reduced extent of resection status shortened progression-free survival for near- versus gross-total resection [hazard ratio (HR) 2.87, 95% CI 1.24-6.65] and sub- versus near-total resection (HR 2.10; 95% CI 1.00-4.40). Complication comparisons between microscopy, endoscopy, and iMRI revealed increased perioperative deaths for endoscopy versus microscopy (4/209 and 0/237, respectively), but this difference was non-significant considering multiple post hoc comparisons (Fisher exact, p = 0.24). CONCLUSIONS: Combined use of endoscopy and iMRI increased pituitary adenoma extent of resection status compared to conventional transsphenoidal microsurgery, and increased extent of resection status was associated with longer progression-free survival. Treatment modality combination did not significantly impact complication rate.