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.

Tumor Embolization

Tumor Embolization

Indications

Tumor embolization is a procedure that can be performed prior to a planned surgical resection. Embolization shuts down the blood supply to a tumor reducing blood loss during surgical resection. A secondary benefit from embolization can be that tumor margins are more easily identified and a tumor can be removed more completely and with less effort. Tumors of the spine, head, and neck that can be embolized have relatively large blood vessels supplying the tumor.

● meningiomas:see Preoperative embolization of intracranial meningioma.

● hemangiopericytomas

● juvenile nasopharyngeal angiofibromas

● paraganglioma’s (carotid body tumor, glomus vagale, glomus jugulare),

● aneurysmal bone cyst

● hemangioblastomas

● vascular metastases from renal cell, thyroid, and chorio cancers.

Technique

A sheath is placed in the femoral artery and a guide catheter is positioned as close as possible to the vessels of interest e.g., in case of a meningioma the guide catheter tip is positioned in the proximal ECA. Angiography and roadmapping are performed through the guide catheter. Using fluoroscopy and road mapping, a microcatheter is advanced over wire into the branches supplying the tumor. Angiography is performed through the microcatheter to ascertain the branch supplies the tumor and no concerning collaterals with intracranial circulation exist. A blank road map is obtained and embolization commenced. PVA particles or Onyx may be used for embolization. In case of Onyx, a DMSO compatible catheter must be used. PVA may be cheaper and quicker to use for tumor embolization. However, the devascularization is not durable and the occluded ves- sels may recanalize; therefore, with PVA the surgery should be performed within a few days of the embolization.


If a tumor has a prominent blood supply then flow can be shut down to the tumor using 3 types of agents. All agents essentially perform the same task, i.e. reducing blood flow; however, they have slightly different properties and are used for different benefits.

NBCA or Onyx™ are polymer agents that consolidate over time and have similar properties to conventional superglues that are pushed through a catheter flowing forward from the catheter tip into vessels just short of the tumor itself. When forward flow stops they form a dense plug stopping blood supply to the tumor.

Microspheres or microbeads are tiny polyvinyl alcohol spheres or particles suspended in a sterile solution that are pushed through a catheter flowing forward from the catheter tip into vessels just short of the tumor itself. As they flow forward the vessel narrows and the particles lodge within the vessel forming a dam. As more particles lodge again a dense plug forms and blood flow stops.

Microcoils are tiny coils, similar to a “miniature slinky,” made from platinum or platinum like alloys that are pushed through a catheter with a special pusher rod. The coil deploys at the tip of the catheter and initially forms a mesh within the vessel being treated. More coils can then be deployed into the mesh. As coils are deployed the mesh structure reduces blood flow and when enough mesh is present, blood flow stops.

Timing

Embolization before surgical resection of tumors has been demonstrated to reduce intraoperative blood loss, but the optimal time that should elapse between embolization and tumor resection has not been established. We evaluated whether immediate surgical resection (< or =24 h) after embolization or delayed surgical resection (>24 h) was more effective in minimizing intraoperative blood loss.

Complications

Embolization for feeders other than ECA and use of liquid materials could increase the complication rate in intracranial tumor embolization 1).

References

1)

Hishikawa T, Sugiu K, Murai S, Takahashi Y, Kidani N, Nishihiro S, Hiramatsu M, Date I, Satow T, Iihara K, Sakai N; JR-NET2 and JR-NET3 study groups. A comparison of the prevalence and risk factors of complications in intracranial tumor embolization between the Japanese Registry of NeuroEndovascular Therapy 2 (JR-NET2) and JR-NET3. Acta Neurochir (Wien). 2019 Jun 7. doi: 10.1007/s00701-019-03970-w. [Epub ahead of print] PubMed PMID: 31172282.

Tumor associated trigeminal neuralgia

Tumor associated trigeminal neuralgia

Trigeminal neuralgia pathogenesis is uncertain. What is nominated as typically TN is idiopathic, but may be due to a structural lesion:

Posterior fossa tumor1) 2) 3) 4) 5), contralateral posterior fossa tumors, 6) 7)ipsilateral and contralateral supratentorial tumor8) 9) 10) 11) 12).

Trigeminal neuralgia in vestibular schwannoma 13).

Trigeminal neuralgia as the initial manifestation of temporal glioma 14).

A supratentorial tumor can initiate TN even without a direct involvement of the trigeminal ganglion or nerve. Such tumors may lead to increased intracranial pressure and brain shift generating a pressure cone that distorts the brain stemand displaces an adjacent vessel, compressing the trigeminal nerve root.

Another explanatory mechanism in a patient with supratentorial tumor and hydrocephalus can be that pressure over the trigeminal sensory root rather than stretching of the nerve fiber leads to TN 15).

References

1) , 6)

Deshmukh VR, Hott JS, Tabrizi P, Nakaji P, Feiz-Erfan I, Spetzler RF. Cavernous malformation of the trigeminal nerve manifesting with trigeminal neuralgia: Case report. Neurosurgery. 2005;56:E623.
2) , 9)

Deshpande S, Kaptain GJ, Pobereskin LH. Temporal glioblastoma causing trigeminal neuralgia. J Neurosurg. 1999;91:515.
3)

Gnanalingham K, Joshi SM, Lopez B, Ellamushi H, Hamlyn P. Trigeminal neuralgia secondary to Chiari’s malformation–treatment with ventriculoperitoneal shunt. Surg Neurol. 2005;63:586–8. discussion 588-9.
4) , 7) , 10)

Goel A, Sham A. Trigeminal neuralgia in the presence of ectatic basilar artery and basilar invagination: Treatment by foramen magnum decompression: Case report. J Neurosurg. 2009;111:1220–2.
5)

Peñarrocha-Diago M, Mora-Escribano E, Bagán JV, Peñarrocha-Diago M. Neoplastic trigeminal neuropathy: Presentation of 7 cases. Med Oral Patol Oral Cir Bucal. 2006;11:E106–11.
8)

Cirak B, Kimaz N, Arslanoglu A. Trigeminal neuralgia caused by intracranial epidermoid tumor: Report of a case and review of different therapeutic modalities. Pain Physician. 2004;7:129–32.
11)

Guttal KS, Naikmasur VG, Joshi SK, Bathi RJ. Trigeminal neuralgia secondary to epidermoid cyst at the cerebellopontine angle: Case report and brief review. Odontology. 2009;97:54–6.
12)

Love S, Coakham HB. Trigeminal neuralgia: Pathology and pathogenesis. Brain. 2001;124:2347–60.
13)

Apostolakis S, Karagianni A, Mitropoulos A, Filias P, Vlachos K. Trigeminal neuralgia in vestibular schwannoma: Atypical presentation and neuroanatomical correlations. Neurochirurgie. 2019 Mar 21. pii: S0028-3770(19)30024-4. doi: 10.1016/j.neuchi.2019.01.001. [Epub ahead of print] PubMed PMID: 30905383.
14)

Khalatbari M, Amirjamshidi A. Trigeminal neuralgia as the initial manifestation of temporal glioma: Report of three cases and a review of the literature. Surg Neurol Int. 2011;2:114. doi: 10.4103/2152-7806.83734. Epub 2011 Aug 13. PubMed PMID: 21886887; PubMed Central PMCID: PMC3162802.
15)

Cirak B, Kimaz N, Arslanoglu A. Trigeminal neuralgia caused by intracranial epidermoid tumor: Report of a case and review of different therapeutic modalities. Pain Physician. 2004;7:129–32.
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