Glioblastoma extent of resection

Glioblastoma extent of resection

Increasing the extent of resection (EOR) of glioblastoma is associated with prolonged survival 1).

Gross total resection of GBM is associated with a decreased incidence of patient safety indicators (PSIs) and hospital-acquired conditions (HACs), as compared to subtotal resection 2).


The relationship between the extent of glioblastoma (GB) resection and clinical benefit depends critically on the balance between cytoreduction and avoiding neurologic morbidity. The definition of the extent of tumor resection, how this is best-measured pre- and postoperatively, and its relation to the volume of residual tumor is still discussed. In 2020 Wykes et al. reviewed the literature supporting the extent of resection in GB, highlighting the importance of a standardized definition and measurement of the extent of resection to allow greater collaboration in research projects and trials. Recent developments in neurosurgical techniques and technologies focused on maximizing extent of resection and safety are discussed 3).


Inoue et al. investigated the relationship of tumor volume between MRI and 11C methionine positron emission tomography and also the relationship between Met uptake index and tumor activity. In ten patients, tumor-to-contralateral normal brain tissue ratio (TNR) was calculated to evaluate metabolic activity of Met uptake areas which were divided into five subareas by the degrees of TNR. In each GBM, tumor tissue was obtained from subareas showing the positive Met uptake. Immunohistochemistry was performed to examine the tumor proliferative activity and the existence of GSCs. In all patients, the volume of Met uptake area at TNR ≦ 1.4 was larger than that of the Gd-enhanced area. The Met uptake area at TNR 1.4 beyond the Gd-enhanced tumor was much wider in high invasiveness-type GBMs than in those of low invasiveness type, and survival was much shorter in the former than the latter types. Immunohistochemistry revealed the existence of GSCs in the area showing Met uptake at TNR 1.4 and no Gd enhancement. Areas at TNR > 1.4 included active tumor cells with a relatively high Ki-67 labeling index. In addition, it was demonstrated that GSCs could exist beyond the border of the Gd-enhanced tumor. Therefore, to obtain maximum resection of GBMs, including infiltrating GSCs, an aggressive surgical excision that includes the Met-positive area at TNR 1.4 should be considered 4).


Using volumetric analysis, it is possible to quantify the EOR using MR imaging. Prior studies using semi-automated methods for this purpose found a high interobserver agreement 5) 6).

However, when manual segmentation is used, a low interobserver agreement in the assessment of tumor resection rates on magnetic resonance imaging (MRI) is described. This applies particularly for post-operative tumor volume and residual tumor volume 7).

Before the general use of post-operative scanning, intraoperative estimation was used to determine partial resectionsubtotal resection, or total resection. The only study that compared this estimation with the presence of residual tumor mass on an MR image, dates back to 1994 8).


The border zone of different tissues is often the object of discussion, considering that the definition of the border is always ambiguous, especially in cases of tumor. The population of different cells in this area largely depends on the character of those cells in terms of the ability of cell motility and the status of tissue barrier, such as extracellular matrices. Gliomas, especially malignant gliomas, are known to possess a highly invasive nature. The surgical extent of resection is determined by the intraoperative macroscopic appearance, sometimes assisted by the information of a navigation system based on the preoperative images, that is easily influenced by the intraoperative brain shift in many cases. Therefore, the surgery often results in an incomplete resection 9).

The value of incomplete resection in Glioblastoma surgery remains questionable. If gross total resection (GTR) cannot be safely achieved, biopsy only might be used as an alternative surgical strategy 10).

Wounded glioma syndrome

see Wounded glioma syndrome.

Contrast-enhancing residual tumor volume (CE-RTV) alone has rarely been analyzed quantitatively to determine if it is a predictor of outcome.

CE-RTV and EOR were found to be significant predictors of survival after GBM resection. CERTV was the more significant predictor of survival compared with EOR, suggesting that the volume of residual contrast-enhancing tumor may be a more accurate and meaningful reflection of the pathobiology of GBM 11).

Difficulties

It is difficult to reproducibly judge EOR in studies due to the lack of reliable tumor segmentation methods, especially for postoperative magnetic resonance imaging (MRI) scans. Therefore, a reliable, easily distributable segmentation method is needed to permit valid comparison, especially across multiple sites.

Cordova et al. report a segmentation method that combines versatile region-of-interest blob generation with automated clustering methods. Applied this to glioblastoma cases undergoing FGS and matched controls to illustrate the method’s reliability and accuracy. Agreement and interrater variability between segmentations were assessed using the concordance correlation coefficient, and spatial accuracy was determined using the Dice similarity index and mean Euclidean distance. Fuzzy C-means clustering with three classes was the best performing method, generating volumes with high agreement with manual contouring and high interrater agreement preoperatively and postoperatively. The proposed segmentation method allows tumor volume measurements of contrast-enhanced T 1-weighted images in the unbiased, reproducible fashion necessary for quantifying EOR in multicenter trials 12).

Maximal safe resection

see Glioblastoma Maximal Safe Resection.

Case series

Glioblastoma extent of resection case series.

References

1)

Sanai N, Polley MY, McDermott MW, Parsa AT, Berger MS (2011) An extent of resection threshold for newly diagnosed glioblastomas. J Neurosurg 115:3–8. https://doi.org/10.3171/2011.2. jns1099810.3171/2011.7.jns10238
2)

Laurent D, Freedman R, Cope L, Sacks P, Abbatematteo J, Kubilis P, Bova F, Rahman M. Impact of Extent of Resection on Incidence of Postoperative Complications in Patients With Glioblastoma. Neurosurgery. 2020 May 1;86(5):625-630. doi: 10.1093/neuros/nyz313. PubMed PMID: 31342060.
3)

Wykes V, Zisakis A, Irimia M, Ughratdar I, Sawlani V, Watts C. Importance and Evidence of Extent of Resection in Glioblastoma. J Neurol Surg A Cent Eur Neurosurg. 2020 Oct 13. doi: 10.1055/s-0040-1701635. Epub ahead of print. PMID: 33049795.
4)

Inoue A, Ohnishi T, Kohno S, Ohue S, Nishikawa M, Suehiro S, Matsumoto S, Ozaki S, Fukushima M, Kurata M, Kitazawa R, Shigekawa S, Watanabe H, Kunieda T. Met-PET uptake index for total tumor resection: identification of (11)C-methionine uptake index as a goal for total tumor resection including infiltrating tumor cells in glioblastoma. Neurosurg Rev. 2020 Feb 15. doi: 10.1007/s10143-020-01258-7. [Epub ahead of print] PubMed PMID: 32060762.
5)

Chow DS, Qi J, Guo X, Miloushev VZ, Iwamoto FM, Bruce JN, Lassman AB, Schwartz LH, Lignelli A, Zhao B, Filippi CG (2014) Semiautomated volumetric measurement on postcontrast MR imaging for analysis of recurrent and residual disease in glioblastoma multiforme. AJNR Am J Neuroradiol 35:498–503. https://doi.org/ 10.3174/ajnr.A3724
6)

Kanaly CW, Mehta AI, Ding D, Hoang JK, Kranz PG, Herndon JE 2nd, Coan A, Crocker I, Waller AF, Friedman AH, Reardon DA, Sampson JH (2014) A novel, reproducible, and objective method for volumetric magnetic resonance imaging assessment of enhancing glioblastoma. J Neurosurg 121:536–542. https://doi.org/10. 3171/2014.4.Jns121952
7)

Kubben PL, Postma AA, Kessels AG, van Overbeeke JJ, van Santbrink H (2010) Intraobserver and interobserver agreement in volumetric assessment of glioblastoma multiforme resection. Neurosurgery 67:1329–1334. https://doi.org/10.1227/NEU. 0b013e3181efbb08
8)

Albert FK, Forsting M, Sartor K, Adams HP, Kunze S (1994) Early postoperative magnetic resonance imaging after resection of malignant glioma: objective evaluation of residual tumor and its influence on regrowth and prognosis. Neurosurgery 34:45–60 discussion 60- 41
9)

Yamaguchi F. The Border Zone of Tumor. Where is the Border? What is a Surgical Border for Patients? World Neurosurg X. 2019 Jan 24;2:100011. doi: 10.1016/j.wnsx.2019.100011. eCollection 2019 Apr. PubMed PMID: 31218286; PubMed Central PMCID: PMC6580876.
10)

Kreth FW, Thon N, Simon M, Westphal M, Schackert G, Nikkhah G, Hentschel B, Reifenberger G, Pietsch T, Weller M, Tonn JC; German Glioma Network.. Gross total but not incomplete resection of glioblastoma prolongs survival in the era of radiochemotherapy. Ann Oncol. 2013 Dec;24(12):3117-23. doi: 10.1093/annonc/mdt388. PubMed PMID: 24130262.
11)

Grabowski MM, Recinos PF, Nowacki AS, Schroeder JL, Angelov L, Barnett GH, Vogelbaum MA. Residual tumor volume versus extent of resection: predictors of survival after surgery for glioblastoma. J Neurosurg. 2014 Nov;121(5):1115-23. doi: 10.3171/2014.7.JNS132449. Epub 2014 Sep 5. PubMed PMID: 25192475.
12)

Cordova JS, Schreibmann E, Hadjipanayis CG, Guo Y, Shu HK, Shim H, Holder CA. Quantitative tumor segmentation for evaluation of extent of glioblastoma resection to facilitate multisite clinical trials. Transl Oncol. 2014 Feb 1;7(1):40-7. eCollection 2014 Feb. PubMed PMID: 24772206; PubMed Central PMCID: PMC3998691.

5-aminolevulinic-acid guided resection

5-aminolevulinic-acid guided resection

In addition to stereotactic localization as well as intraoperative brain mapping, techniques to enhance visual identification of tumor intraoperatively may be used and include 5-aminolevulinic-acid (5-ALA). 5-ALA is metabolized into fluorescent porphyrins, which accumulate in malignant glioma cells. These property permits use of ultraviolet illumination during surgery as an adjunct to map out the tumor. This has been proven with RCT where the use of 5-ALA leads to more complete resection (65% vs. 36%, p < 0.0001), which translates into a higher 6-month progression-free survival (41% vs. 21.1%, p = 0.0003) but no effect on OS 1).


Fluorescein can be used as a viable alternative to 5-ALA for intraoperative fluorescent guidance in brain tumor surgery. Comparative, prospective, and randomized studies are much needed 2)

Indications

Doses

The highest visible and measurable fluorescence was yielded by 20 mg/kg. No fluorescence was elicited at 0.2 mg/kg. Increasing 5-ALA doses did not result in proportional increases in tissue fluorescence or PPIX accumulation in plasma, indicating that doses higher than 20 mg/kg will not elicit useful increases in fluorescence 3).


Application of 5mg/kg ALA was evaluated as equally reliable as the higher dose regarding the diagnostic performance when guidance was performed using a spectroscopic system. Moreover, no PpIX was detected in the skin of the patients 4).

Over time, several other tumour entities have been identified to metabolize 5-ALA and show a similar fluorescence pattern during surgical resection.

Further research is warranted to determine the role of 5-ALA accumulation in post-ischaemic and inflammatory brain tissue 5).

The positive predictive values (PPVs), of utilizing the most robust ALA fluorescence intensity (lava-like orange) as a predictor of tumor presence is high. However, the negative predictive values (NPVs), of utilizing the absence of fluorescence as an indicator of no tumor is poor. ALA intensity is a strong predictor for degree of tumor cellularity for the most fluorescent areas but less so for lower ALA intensities. Even in the absence of tumor cells, reactive changes may lead to ALA fluorescence 6).

Reviews

Senders et al., systematically review all clinically tested fluorescent agents for application in fluorescence guided surgery (FGS) for glioma and all preclinically tested agents with the potential for FGS for glioma.

They searched the PubMed and Embase databases for all potentially relevant studies through March 2016.

They assessed fluorescent agents by the following outcomes: rate of gross total resection (GTR), overall and progression free survival, sensitivity and specificity in discriminating tumor and healthy brain tissue, tumor-to-normal ratio of fluorescent signal, and incidence of adverse events.

The search strategy resulted in 2155 articles that were screened by titles and abstracts. After full-text screening, 105 articles fulfilled the inclusion criteria evaluating the following fluorescent agents: 5 aminolevulinic acid (5-ALA) (44 studies, including three randomized control trials), fluorescein (11), indocyanine green (five), hypericin (two), 5-aminofluorescein-human serum albumin (one), endogenous fluorophores (nine) and fluorescent agents in a pre-clinical testing phase (30). Three meta-analyses were also identified.

5-ALA is the only fluorescent agent that has been tested in a randomized controlled trial and results in an improvement of GTR and progression-free survival in high-grade gliomas. Observational cohort studies and case series suggest similar outcomes for FGS using fluorescein. Molecular targeting agents (e.g., fluorophore/nanoparticle labeled with anti-EGFR antibodies) are still in the pre-clinical phase, but offer promising results and may be valuable future alternatives. 7).

Complications

Despite its benefits, 5-ALA has not reached widespread popularity in the United States, primarily because of lack of Food and Drug Administration (FDA) approval. Even if it were approved, 5-ALA does have specific limitations including low depth of penetration, autofluorescence of background parenchyma


Findings suggest that the administration of 5-ALA or the combined effect of 5-ALA, anaesthesia and tumour resection can cause a mild and reversible elevation in liver enzymes. It therefore appears safe to change the regime of monitoring. Routine blood samples are thus abolished, though caution remains necessary in patients with known liver impairment 8).

For near infrared imaging, additional investigators have explored fluorescein as well as novel near-infrared (NIR) agents 9) 10) 11)

Stummer et al. showed that 5–ALA guided resections carry a higher risk of post-operative neurological deterioration than conventional resections (26% vs 15%, respectively), even though the difference vanished within weeks 12).

Just as tumour tissue is often indiscernible from normal brain tissue, functionally critical tissues are indistinguishable from tissues with less clinically relevant functions.

Thus, knowing when to stop a resection due to proximity to areas of crucial neurological functions is of obvious and utmost importance. Detailed knowledge of the normal brain anatomy and distribution of function is not sufficient during glioma resection. Interindividual variability and functional relocation (i.e., plasticity) induced by the presence of an infiltrating tumour 13) requires an exact functional brain map at the site of surgery in order to spare areas involved in crucial (so-called eloquent) functions. Preoperative localisation of function, either with functional MRI (fMRI) or navigated transcranial magnetic stimulation (nTMS), provides an approximate map 14) 15).

Furthermore, intra-operative direct cortical and subcortical electrical stimulation (DCS) for functional analysis of the tissue in the tumour’s infiltration zone is required for accurate identification of areas that need to be spared in order to retain the patient’s functional integrity 16) 17). Motor evoked potentials (MEP) provide real-time information on the integrity of the primary motor cortex and the corticospinal tract 18). Direct cortical mapping and phase reversal identify the primary motor and sensory cortices. Subcortical mapping can estimate the distance to the pyramidal tract, acting as guidance close to functionally critical areas 19). When integrated into the existing surgical tools, continuous and dynamic mapping enables more extensive resection while simultaneously protecting motor function 20). Using these techniques and a detailed electrophysiological “Bern-concept”, a group achieved complete motor function protection in 96% of patients with high-risk motor eloquent tumours 21). Furthermore, localisation of cortical and subcortical regions relevant to language function is essential for speech preservation during resection of gliomas in proximity to presumed speech areas 22) and requires the patient to be awake during the brain mapping part of surgery. Similarly, intra-operative mapping of visual functions may contribute to increased resections while avoiding tissue essential for vision within the temporal and occipital lobes 23).

References

1)

Stummer W, Pichlmeier U, Meinel T, Wiestler OD, Zanella F, Reulen HJ; ALA-Glioma Study Group. Fluorescence-guided surgery with 5-aminolevulinic acid for resection of malignant glioma: a randomised controlled multicentre phase III trial. Lancet Oncol. 2006 May;7(5):392-401. PubMed PMID: 16648043.
2)

Hansen RW, Pedersen CB, Halle B, Korshoej AR, Schulz MK, Kristensen BW, Poulsen FR. Comparison of 5-aminolevulinic acid and sodium fluorescein for intraoperative tumor visualization in patients with high-grade gliomas: a single-center retrospective study. J Neurosurg. 2019 Oct 4:1-8. doi: 10.3171/2019.6.JNS191531. [Epub ahead of print] PubMed PMID: 31585425.
3)

Stummer W, Stepp H, Wiestler OD, Pichlmeier U. Randomized, Prospective Double-Blinded Study Comparing 3 Different Doses of 5-Aminolevulinic Acid for Fluorescence-Guided Resections of Malignant Gliomas. Neurosurgery. 2017 Apr 1. doi: 10.1093/neuros/nyx074. [Epub ahead of print] PubMed PMID: 28379547.
4)

Haj-Hosseini N, Richter J, Hallbeck M, Wårdell K. Low dose 5-aminolevulinic acid: Implications in spectroscopic measurements during brain tumor surgery. Photodiagnosis Photodyn Ther. 2015 Mar 25. pii: S1572-1000(15)00031-9. doi: 10.1016/j.pdpdt.2015.03.004. [Epub ahead of print] PubMed PMID: 25818546.
5)

Behling F, Hennersdorf F, Bornemann A, Tatagiba M, Skardelly M. 5-Aminolevulinic acid accumulation in a cerebral infarction mimicking high-grade glioma, a case report. World Neurosurg. 2016 May 10. pii: S1878-8750(16)30271-6. doi: 10.1016/j.wneu.2016.05.009. [Epub ahead of print] PubMed PMID: 27178236.
6)

Lau D, Hervey-Jumper SL, Chang S, Molinaro AM, McDermott MW, Phillips JJ, Berger MS. A prospective Phase II clinical trial of 5-aminolevulinic acid to assess the correlation of intraoperative fluorescence intensity and degree of histologic cellularity during resection of high-grade gliomas. J Neurosurg. 2015 Nov 6:1-10. [Epub ahead of print] PubMed PMID: 26544781.
7)

Senders JT, Muskens IS, Schnoor R, Karhade AV, Cote DJ, Smith TR, Broekman ML. Agents for fluorescence-guided glioma surgery: a systematic review of preclinical and clinical results. Acta Neurochir (Wien). 2017 Jan;159(1):151-167. doi: 10.1007/s00701-016-3028-5. Review. PubMed PMID: 27878374; PubMed Central PMCID: PMC5177668.
8)

Offersen CM, Skjoeth-Rasmussen J. Evaluation of the risk of liver damage from the use of 5-aminolevulinic acid for intra-operative identification and resection in patients with malignant gliomas. Acta Neurochir (Wien). 2016 Nov 10. [Epub ahead of print] PubMed PMID: 27832337.
9)

Shinoda J, Yano H, Yoshimura SI, et al. Fluorescence-guided resection of glioblastoma multiforme by using high-dose fluorescein sodium. Technical note. J Neurosurg. 2003;99(3):597–603.
10)

Rey-Dios R, Cohen-Gadol AA. Technical principles and neurosurgical applications of fluorescein fluorescence using a microscope-integrated fluorescence module. Acta Neurochir (Wien). 2013;155(4):701–706.
11)

Swanson KI, Clark PA, Zhang RR, et al. Fluorescent cancer-selective alkylphosphocholine analogs for intraoperative glioma detection. Neurosurgery. 2015;76(2):115–123.
12)

Stummer W1, Tonn JC, Mehdorn HM, Nestler U, Franz K, Goetz C, et al. ALA-Glioma Study Group. Counterbalancing risks and gains from extended resections in malignant glioma surgery: a supplemental analysis from the randomized 5–aminolevulinic acid glioma resection study. J Neurosurg. 2011;114(3):613–23. doi: 10.3171/2010.3
13)

Ojemann G, Ojemann J, Lettich E, Berger M. Cortical language localization in left, dominant hemisphere. An electrical stimulation mapping investigation in 117 patients. J Neurosurg. 1989;71(3):316–26.
14)

Seghier ML, Lazeyras F, Pegna AJ, Annoni JM, Zimine I, Mayer E, et al. Variability of fMRI activation during a phonological and semantic language task in healthy subjects. Hum Brain Mapp. 2004;23(3):140–55.
15)

Krieg SM, Shiban E, Buchmann N, Gempt J, Foerschler A, Meyer B, et al. Utility of presurgical navigated transcranial magnetic brain stimulation for the resection of tumors in eloquent motor areas. J Neurosurg. 2012;116(5):994–1001. doi: 10.3171/2011.12.JNS111524
16) , 22)

Duffau H, Capelle L, Sichez N, Denvil D, Lopes M, Sichez JP, et al. Intraoperative mapping of the subcortical language pathways using direct stimulations. An anatomo-functional study. Brain. 2002;125(1):199–214.
17)

Duffau H, Capelle L, Denvil D, Sichez N, Gatignol P, Taillandier L, et al. Usefulness of intraoperative electrical subcortical mapping during surgery for low-grade gliomas located within eloquent brain regions: functional results in a consecutive series of 103 patients. J Neurosurg. 2003;98(4):764–78.
18)

Seidel K, Beck J, Stieglitz L, Schucht P, Raabe A. The warning-sign hierarchy between quantitative subcortical motor mapping and continuous motor evoked potential monitoring during resection of supratentorial brain tumors. J Neurosurg. 2013;118(2):287–96.
19)

Seidel K, Beck J, Stieglitz L, Schucht P, Raabe A. Low Threshold Monopolar Motor Mapping for Resection of Primary Motor Cortex Tumors. Neurosurgery. 2012;71(1):104–14.
20)

Raabe A, Beck J, Schucht P, Seidel K. Continuous dynamic mapping of the corticospinal tract during surgery of motor eloquent brain tumors: evaluation of a new method. J Neurosurg. 2014;120(5)1015–24. doi: 10.3171/2014.1.JNS13909.
21)

Schucht P, Seidel K. Beck J, Murek M, Jilch A, Wiest R, et al. Intraoperative monopolar mapping during 5-ALA-guided resections of glioblastomas adjacent to motor eloquent areas: evaluation of resection rates and neurological outcome. Neurosurg Focus. 2014;27(6):E16.
23)

Gras-Combe G, Moritz-Gasser S, Herbet G, Duffau H. Intraoperative subcortical electrical mapping of optic radiations in awake surgery for glioma involving visual pathways. J Neurosurg. 2012;117(3):466–73.

Diffusion tensor imaging for brain tumor resection

Diffusion tensor imaging for brain tumor resection

Preserving subcortical connectivity is crucial in optimizing functional outcomes of patients undergoing surgery for intraaxial tumors.

Diffusion tensor imaging (DTI) attempts to aid in the preservation of these subcortical networks by providing a framework for localizing these tracts in relation to the surgical target. DTI takes advantage of the anisotropic diffusion of water along white matter fiber bundles, which can be assessed with magnetic resonance imaging (MRI). Postprocessing platforms are used to map the tracts, which can then be integrated into neuronavigation. This permits the neurosurgeon to ascertain the location and orientation of major white matter tracts for preoperative and intraoperative decision making.


Diffusion tensor imaging (DTI) based on echo planar imaging (EPI) can suffer from geometric image distortions in comparison to conventional anatomical magnetic resonance imaging (MRI). Therefore, DTI-derived information, such as fiber tractography (FT) used for treatment planning of brain tumors, might be associated with spatial inaccuracies when linearly projected on anatomical MRI.

Gerhardt et al., indicated that semi-elastic image fusion can be used for retrospective distortion correction of DTI data acquired for image guidance, such as DTI FT as used for a broad range of clinical indications 1).


The exact utility and practical application of DTI in brain tumor resection continue to be refined. On the one hand, the historical difficulty in obtaining DTI (especially with respect to postprocessing) has made its implementation in neurosurgical practices somewhat limited. Adding to this barrier, the majority of studies describing DTI are placed within a methodological framework that emphasizes the physics and computational analysis of the modality itself, a perspective that is less directly applicable to neurosurgeons wanting to apply DTI to clinical practice. On the other hand, fundamental questions about the utility of the tool have been raised by leaders in the field 2) 3) 4) 5) 6) 7) 8) 9).


Conventional white matter (WM) imaging approaches, such as diffusion tensor imaging (DTI), have been used to preoperatively identify the location of affected WM tracts in patients with intracranial tumors in order to maximize the extent of resection and potentially reduce postoperative morbidity.

Preoperative diffusion tensor imaging (DTI) is used to demonstrate corticospinal tract (CST) position. Intraoperative brain shifts may limit preoperative DTI value, and studies characterizing such shifts are lacking.

For nonenhancing intraaxial tumors, preoperative DTI is a reliable method for assessing intraoperative tumor-to-CST distance because of minimal intraoperative shift, a finding that is important in the interpretation of subcortical motor evoked potential to maximize extent of resection and to preserve motor function. In resection of intra-axial enhancing tumors, intraoperative imaging studies are crucial to compensate for brain shift 10).

Case series

A total of 34 patients were included in this study. Pre-operative contrast-enhanced magnetic resonance imaging and DTI scans of the patients were taken into consideration. Pre- and post-operative neurological examinations were performed and the outcome was assessed.

Preoperative planning of surgical corridor and extent of resection were planned so that maximum possible resection could be achieved without disturbing the WM tracts. DTI indicated the involvement of fiber tracts. A total of 21 (61.7%) patients had a displacement of tracts only and they were not invaded by tumor. A total of 11 (32.3%) patients had an invasion of tracts by the tumor, whereas in 4 (11.7%) patients the tracts were disrupted. Postoperative neurologic examination revealed deterioration of motor power in 4 (11.7%) patients, deterioration of language function in 3 (8.82%) patients, and memory in one patient. Total resection was achieved in 11/18 (61.1%) patients who had displacement of fibers, whereas it was achieved in 5/16 (31.2%) patients when there was infiltration/disruption of tracts.

DTI provided crucial information regarding the infiltration of the tract and their displaced course due to the tumor. This study indicates that it is a very important tool for the preoperative planning of surgery. The involvement of WM tracts is a strong predictor of the surgical outcome 11).

References

1)

Gerhardt J, Sollmann N, Hiepe P, Kirschke JS, Meyer B, Krieg SM, Ringel F. Retrospective distortion correction of diffusion tensor imaging data by semi-elastic image fusion – Evaluation by means of anatomical landmarks. Clin Neurol Neurosurg. 2019 Jun 10;183:105387. doi: 10.1016/j.clineuro.2019.105387. [Epub ahead of print] PubMed PMID: 31228706.
2)

Nimsky C. Fiber tracking: we should move beyond diffusion tensor imaging. World Neurosurg. 2014;82(1-2):35–36.
3)

Farquharson STournier JDCalamante F. et al White matter fiber tractography: why we need to move beyond DTI. J Neurosurg. 2013;118(6):1367–1377.
4)

Fernandez-Miranda JC. Editorial: beyond diffusion tensor imaging. J Neurosurg. 2013;118(6):1363–1365; discussion 1365-1366.
5)

Lerner AMogensen MAKim PEShiroishi MSHwang DHLaw M. Clinical applications of diffusion tensor imaging. World Neurosurg. 2014;82(1-2):96–109.
6)

Feigl GCHiergeist WFellner C. et al Magnetic resonance imaging diffusion tensor tractography: evaluation of anatomic accuracy of different fiber tracking software packages. World Neurosurg. 2014;81(1):144–150.
7)

Duffau H. The dangers of magnetic resonance imaging diffusion tensor tractography in brain surgery. World Neurosurg. 2014;81(1):56–58.
8)

Duffau H. Diffusion tensor imaging is a research and educational tool, but not yet a clinical tool. World Neurosurg. 2014;82(1-2):e43–e45.
9)

Potgieser ARWagemakers Mvan Hulzen ALde Jong BMHoving EWGroen RJ. The role of diffusion tensor imaging in brain tumor surgery: a review of the literature. Clin Neurol Neurosurg. 2014;124C:51–58.
10)

Shahar T, Rozovski U, Marko NF, Tummala S, Ziu M, Weinberg JS, Rao G, Kumar VA, Sawaya R, Prabhu SS. Preoperative Imaging to Predict Intraoperative Changes in Tumor-to-Corticospinal Tract Distance: An Analysis of 45 Cases Using High-Field Intraoperative Magnetic Resonance Imaging. Neurosurgery. 2014 Jul;75(1):23-30. doi: 10.1227/NEU.0000000000000338. PubMed PMID: 24618800.
11)

Dubey A, Kataria R, Sinha VD. Role of Diffusion Tensor Imaging in Brain Tumor Surgery. Asian J Neurosurg. 2018 Apr-Jun;13(2):302-306. doi: 10.4103/ajns.AJNS_226_16. PubMed PMID: 29682025; PubMed Central PMCID: PMC5898096.
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