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Biomedical Journal of Scientific & Technical Research

March 02, 2020, Volume 26, 1, pp 19728-19732

Research Article

Research Article

Utility of Multimodality Imaging Based Target Volume Definition for Radiosurgery of Trigeminal Neuralgia: An Original Article

Ferrat Dincoglan, Selcuk Demiral, Omer Sager* and Murat Beyzadeoglu

Author Affiliations

Department of Radiation Oncology, University of Health Sciences, Gulhane Medical Faculty, Ankara, Turkey

Received: February 21, 2020 | Published: March 02, 2020

Corresponding author: Omer Sager, Department of Radiation Oncology, University of Health Sciences, Gulhane Medical Faculty, Ankara, Turkey

DOI: 10.26717/BJSTR.2020.26.004311

Abstract

Objective: Trigeminal neuralgia, also named “tic douloureux”, is the facial pain which is usually one-sided in the distribution of 5th cranial nerve. After Leksell used radiosurgery as a therapeutic option for trigeminal neuralgia, this treatment modality has been accepted in the treatment of refractory pain caused by trigeminal neuralgia. Studies investigating the role of radiosurgery have rapidly increased regarding the poor results in pain control with invasive procedures, high rates of relapse and remarkable morbidity. Non-invasiveness and effectivity are the most important advantages of radiosurgery. The aim of this study is to assess incorporation of multimodality imaging into target volume definition of trigeminal neuralgia radiosurgery.
Materials and methods: Target definition with and without incorporation of Magnetic Resonance Imaging (MRI) was evaluated for linear accelerator-based radiosurgery of trigeminal neuralgia. Ground truth target volume to be used as the reference was defined by the board-certified treating physicians after comprehensive evaluation and consensus.
Results: Comparative assessment of target volume determination using Computed Tomography (CT) only imaging and CT-MR fusion-based imaging revealed that target volumes generated by CT-MR fusion-based imaging were identical to ground truth target volumes determined by the treatment team consensus.
Conclusion: MRI may serve as a valuable imaging modality improving target definition for linear accelerator-based radiosurgery of trigeminal neuralgia.

Keywords: Trigeminal Neuralgia; Radiosurgery; Magnetic Resonance Imaging (MRI)

Abbreviations: MRI: Magnetic Resonance Imaging; CT: Computed Tomography; RF: Radio Frequency; MVD: Microvascular Decompression; AMOA: Arc Modulation Optimization Algorithm

Introduction

Trigeminal neuralgia, also named “tic douloureux”, is the facial pain which is usually one-sided in the distribution of 5th cranial nerve. The most commonly known cause of trigeminal neuralgia is the vascular compression of the trigeminal nerve [1,2]. The vascular compression is in superior cerebellar artery in 64% of the cases [3]. Vascular compression leads to continuous demyelination and remyelinisation cycles which causes myelinisation abnormalities of the nerve. High frequency ectopic impulses from this impaired myelinisation area may cause pain [4]. Medical treatment is the first step in trigeminal neuralgia that may lead to committing suicides. However, additional therapies are required in the setting of temporary response or refractory pain despite medical treatment. Carbamazepine, fenitoin, gabapentin, and baclofen may be used as medical treatment [5]. Invasive interventions are done when medical treatment is ineffective or when the side effects of medical treatment are unacceptable. Interventional procedures include percutaneous radiofrequency (RF) rhizotomy, percutaneous glycerol rhizotomy, percutaneous balloon micro compression and microvascular decompression (MVD). MVD is the most invasive procedure, however, repeating pain rates are lower with MVD [6]. Relapse is observed approximately in 30% of patients initially treated with MVD.

Studies investigating the role of radiosurgery have rapidly increased regarding the poor results in pain control with invasive procedures, high rates of relapse and remarkable morbidity. Pain relief with radiosurgery in trigeminal neuralgia was first reported in 1951 [7,8]. A subsequent study revealed complete pain responses of 58%-70% with ≥ 70 Gy single dose radiosurgery [9]. In this context, radiosurgery has been used as a treatment modality for management of trigeminal neuralgia as well as several other intracranial and extracranial benign and malign indications [10-32]. The aim of this study is to assess incorporation of multimodality imaging into target volume definition of trigeminal neuralgia radiosurgery.

Materials and Methods

Target definition with and without incorporation of Magnetic Resonance Imaging (MRI) was evaluated for linear acceleratorbased radiosurgery of trigeminal neuralgia in this study. Ground truth target volume to be used as the reference was defined by the board-certified treating physicians after comprehensive evaluation and consensus. Informed consents were provided before treatment, and management with radiosurgery was decided after thorough assessment including multidisciplinary collaboration of experts from neurosurgery, neuroradiology, and radiation oncology. A stereotactic head frame was affixed to the patients’ skull under local anesthesia by use of 4 pins on the day of treatment. Computed Tomography (CT) simulation was performed at the CT simulator (GE Lightspeed RT, GE Healthcare, Chalfont St. Giles, UK). Planning CT images were sent to the contouring workstation (SimMD, GE, UK) for delineation of target volumes and critical structures. Target volume definition for radiosurgery was performed by use of CT simulation images only or fused CT and T1 gadolinium-enhanced MR images.

Target definition with CT only and by incorporation of CT-MR fusion was assessed comparatively. Definition of ground truth target volume was performed by the board-certified treating physicians after comprehensive evaluation and consensus to be used for actual treatment and comparison purposes. ERGO ++ (CMS, Elekta, UK) radiosurgery planning system was used for treatment planning. Synergy (Elekta, UK) Linear Accelerator (LINAC) was used for delivery of radiosurgery. Image Guided Radiation Therapy (IGRT) techniques including kV-CBCT (kilovoltage Cone Beam CT) and XVI (X-ray Volumetric Imaging, Elekta, UK) were used for treatment verification as a routine procedure.

Results

Target volume determination based on CT-only imaging and CT-MR fusion-based imaging was comparatively evaluated. Ground truth target volume defined by board certified treatment team after comprehensive assessment and colleague peer review was identical to target definition using CT-MR fusion-based imaging. Target volume delineation on the planning CT and MR images was optimized by selection of appropriate windows and levels in radiosurgery planning. Contouring accuracy was improved by use of sagittal and coronal images in addition to axial planning CT images. was achieved by use of the Arc Modulation Optimization Algorithm (AMOA) was utilized for optimization of target volume coverage and critical organ sparing. (Figure 1) shows axial planning CT image and (Figure 2) shows the corresponding axial MR image of the same patient with trigeminal neuralgia.

Figure 1: Axial planning CT image of a patient with trigeminal neuralgia.

Figure 2: Corresponding axial MR image of the same patient with trigeminal neuralgia.

Discussion

After Leksell used radiosurgery as a therapeutic option for trigeminal neuralgia, this treatment modality has been accepted in the treatment of refractory pain caused by trigeminal neuralgia. Non-invasiveness and effectivity are the most important advantages of SRS. Many studies evaluated the efficiency of radiosurgery in trigeminal neuralgia. Maesawa et al. [33] reported on 220 patients and > 50% pain relief was achieved in 139 patients. In the study by Kondziolka et al. [34] in 1996, 50 patients from 5 institutions were treated with SRS using a dose of 60-90 Gy. At a median follow-up of 18 months, excellent pain relief was achieved in 58% of patients. This multi-institutional study revealed decreased effect of SRS on pain relief at maximal doses lower than 70 Gy [34]. Young et al. [35] and Zheng et al. [36] found SRS to be effective in the treatment of trigeminal neuralgia in their studies. Effect of the length of the irradiated nerve segment on treatment in SRS for trigeminal neuralgia is controversial. Flickinger et al. [37] used single and double isocenter in the treatment of 57 patients with trigeminal neuralgia. The highest single dose delivered was 75 Gy.

Median follow-up of 26 months revealed no significant improvement in pain response. Facial numbness and paresthesia were correlated with the length of the irradiated nerve segment [37]. In a study by Riesenberger et al. [38] 53 patients with trigeminal neuralgia were treated with single dose frame-based radiosurgery with a follow-up of at least 36 months. Median maximal dose was 80 Gy. 31 patients had significant pain relief after 48 months of follow-up in the study [38]. These results are similar to those achieved with MVD and rhizotomy. However, 36% of patients developed facial numbness after treatment. Kondziolka et al. [39] reported on 503 patients resistant to medical treatment who were treated with radiosurgery. 205 patients had undergone previous surgery and relapsed. Maximal dose was 80 Gy. 85% of patients had pain relief with or without medical treatment [39]. In this study, we assessed incorporation of multimodality imaging into target volume definition of trigeminal neuralgia radiosurgery. Indeed, usefulness of neuroimaging with MRI for definition of central nervous system radiotherapy and radiosurgery target volumes has been an important focus of research in the literature [40-49]. Our results appear to be compatible to these studies supporting the incorporation of MRI in radiosurgery treatment planning. Ground truth target volumes determined by comprehensive evaluation, consensus and colleague peer review were identical to target volumes defined based on CT-MR fusion-based imaging.

Conclusion

In conclusion, our study supports the utilization of MRI to improve target definition for linear accelerator-based radiosurgery of trigeminal neuralgia despite the need for further studies.

References

Research Article

Utility of Multimodality Imaging Based Target Volume Definition for Radiosurgery of Trigeminal Neuralgia: An Original Article

Ferrat Dincoglan, Selcuk Demiral, Omer Sager* and Murat Beyzadeoglu

Author Affiliations

Department of Radiation Oncology, University of Health Sciences, Gulhane Medical Faculty, Ankara, Turkey

Received: February 21, 2020 | Published: March 02, 2020

Corresponding author: Bin Zhao, School of Science, Hubei University of Technology, Wuhan, Hubei, China

DOI: 10.26717/BJSTR.2020.26.004311

Abstract

Objective: Trigeminal neuralgia, also named “tic douloureux”, is the facial pain which is usually one-sided in the distribution of 5th cranial nerve. After Leksell used radiosurgery as a therapeutic option for trigeminal neuralgia, this treatment modality has been accepted in the treatment of refractory pain caused by trigeminal neuralgia. Studies investigating the role of radiosurgery have rapidly increased regarding the poor results in pain control with invasive procedures, high rates of relapse and remarkable morbidity. Non-invasiveness and effectivity are the most important advantages of radiosurgery. The aim of this study is to assess incorporation of multimodality imaging into target volume definition of trigeminal neuralgia radiosurgery.
Materials and methods: Target definition with and without incorporation of Magnetic Resonance Imaging (MRI) was evaluated for linear accelerator-based radiosurgery of trigeminal neuralgia. Ground truth target volume to be used as the reference was defined by the board-certified treating physicians after comprehensive evaluation and consensus.
Results: Comparative assessment of target volume determination using Computed Tomography (CT) only imaging and CT-MR fusion-based imaging revealed that target volumes generated by CT-MR fusion-based imaging were identical to ground truth target volumes determined by the treatment team consensus.
Conclusion: MRI may serve as a valuable imaging modality improving target definition for linear accelerator-based radiosurgery of trigeminal neuralgia.

Keywords: Trigeminal Neuralgia; Radiosurgery; Magnetic Resonance Imaging (MRI)

Abbreviations: MRI: Magnetic Resonance Imaging; CT: Computed Tomography; RF: Radio Frequency; MVD: Microvascular Decompression; AMOA: Arc Modulation Optimization Algorithm