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Table of Contents    
COMMENTARY
Year : 2018  |  Volume : 66  |  Issue : 3  |  Page : 753-754

Surgery for high-grade gliomas using intraoperative MRI and fluorescence


Department of Neurosurgery, Fukushima Medical University, Fukushima, Japan

Date of Web Publication15-May-2018

Correspondence Address:
Dr. Masazumi Fujii
Department of Neurosurgery, Fukushima Medical University, Fukushima
Japan
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/0028-3886.232313

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How to cite this article:
Fujii M. Surgery for high-grade gliomas using intraoperative MRI and fluorescence. Neurol India 2018;66:753-4

How to cite this URL:
Fujii M. Surgery for high-grade gliomas using intraoperative MRI and fluorescence. Neurol India [serial online] 2018 [cited 2018 May 20];66:753-4. Available from: http://www.neurologyindia.com/text.asp?2018/66/3/753/232313




The article in focus describes the authors' experience in using both 5-aminolevulinic acid (5-ALA) and intraoperative magnetic resonance guidance (iMRI) for the resection of malignant gliomas.[1] The theme itself is beneficial for not only Indian readers but also international readers, since the combination of the above two intraoperative technological modalities could enhance the quality of resection of brain tumors. This is certainly of interest to all neurosurgeons undertaking resection of gliomas as the extent of resection has been unequivocally linked to the duration of progression-free survival and often, also to overall outcome of patients. Several questions and comments related to this article spontaneously arise while imbibing the salient issue highlighted by it.

The first point relates to the authors' exhibiting that the two modalities, when used in conjunction, actually facilitated a greater extent of glioma resection than would have been possible when each of these modalities had been used alone. The combination of the two modalities has been already reported by several authors.[2] One of the most important issues that arises is related to the differences between the two modalities and the specific roles played by each of these modalities in ensuring completeness of excision during glioma surgery. Based on the article, complete resection was achieved in 36 cases; and only one patient underwent a subtotal excision of the tumor. The patient who had the tumor-remnant did not undergo additional removal because the remnant was located in a relatively eloquent area. Thus, the tumor remnant was left as a more radical resection would have led to postoperative neurological sequel. It seems that only one of these modalities, either 5-ALA fluorescence-guided or iMRI-guided surgery might have been enough to achieve maximum resection. This fact emerges because the authors have failed to mention in their study, the findings revealed on the iMRI during surgery, whether or not the remnant part of the tumor showed a positive or negative fluorescence, and whether additional resection was performed on the remnant tumor based on the iMRI findings in each case. This is irrespective of whether partial or total excision of the tumor was performed. The authors should have clarified the roles and the characteristic findings observed utilizing the two different modalities during surgery, and then should have shown how “enhanced resection” had been achieved using both the modalities in combination, that was not possible on using either one of these modalities alone.

The second point relates to the fact that the study design is unclear. They must disclose whether this is retrospective or a prospective analysis. They described that they enrolled 37 patients who have a lesion suggestive of a high-grade gliomas and then go on to state that the patients were selected on the basis of their postoperative pathological diagnosis. The total number evaluated in this study ended up being the same number of patients who were initially recruited for the study, that is 37. This means that all the suggested patients were truly high-grade gliomas, without any other pathologies being considered, which actually makes the analysis retrospective. This apparent discrepancy in the recruitment procedure of patients should be clarified appropriately. What was the total number of cases enrolled preoperatively, and what was the number of patients finally chosen to be included in the study? Additionally, what were the histological types of tumors in patients who were excluded after their pathological diagnosis had been established following their surgical excision.

The third point relates to the fact that the extent of resection should have been also discussed in the context of preserving function. In the surgery for infiltrative tumors, such as gliomas, the extent of resection strongly depends upon the tumor location and the tumor infiltration into the eloquent brain area. Intraoperative tumor-imaging modalities are not enough to achieve maximal “safe” resection. Thus, modern glioma surgery frequently uses intraoperative functional monitoring modalities such as motor evoked potentials for motor function, and awake craniotomies for speech and cognitive functions. Intraoperative diffusion tensor imaging (DTI) tractography may play a role under guidance of updated neuro-navigation. I understand that 'the surgeon's judgement' is quite important in real clinical practice; however, this parameter is quite nebulous and can be impossible to ascertain when an objective scientific article is being formulated. The authors should have explained the specific standards utilized by the surgeon to judge the unresectability of the tumors. This would have been of immense benefit to the readers.

The fourth point relates to the fact that the infection rate seems rather high (16% wound infection plus 1 bone flap infection). Although the authors claim that the stated higher incidence of infection was not related to the usage of iMRI, they should have demonstrated reasons for making this statement.

The fifth point relates to the survival analysis. The authors should have, in the study, disclosed the definitions of progression-free survival and the overall-survival that the study followed, namely, at what time point was the starting point of calculation. Was it the date of surgery or the date of starting of adjuvant chemo-radiotherapy?

They should have shown the protocols of the initial adjuvant therapy (the chemotherapeutic agents used and the dose of radiation utilized). They should also have dwelt upon the therapeutic options resorted to, when they encountered recurrence of the tumor in their patients (the second line chemotherapy, the additional radiation therapy and surgery, etc.), since these parameters have a strong influence on the progression of tumors and the survival of patients.

The intent of the article, that is, the simultaneous use of two intraoperative imaging technologies in order to enhance the safe excision of malignant gliomas, is laudable. A greater emphasis on the technical issues of this article would have further enhanced its value for the readers.



 
  References Top

1.
Sharma V, Kedia R, Narang KS, Ajaya N. Jha AN. Enhanced resection of primary high-grade gliomas using a combination of intraoperative magnetic resonance imaging and intraoperative fluorescence (5-aminolevulinic acid): A single-centre experience. Neurol India 2018;66:747-52.  Back to cited text no. 1
  [Full text]  
2.
Coburger J, Hagel V, Wirstz CR, König C. Surgery for glioblastoma: Impact of the combined use of 5-aminolevulinic acid and intraoperative MRI on extent of resection and survival. Plos One 2015:10(6):e0131872. Available from: https://doi.org/10.1371/journal.pone.0131872. [Last accessed on 2018 May 04].  Back to cited text no. 2
    




 

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