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fluorescence guidance have not studied the tumor genes and   in control.  It is clear  that the group analysis was not
                                                                       [2]
           the good results could be genetically related. Further studies   homogeneous and it might be due to a lack of protocols and
           are  needed  to  direct  correlate  the  genetically  aggressive   a standardized approach to all lesions. Furthermore, there is
           tumors and the use of 5-ALA.                       need for standardization of reports for a systematic-review
                                                              analysis and for future trends. Even though, the theorical
           Another substance used for guidance is the sodium   benefits  of  the  novel  techniques  should  impulse  more
           fluorescence, which accumulates in high neovascularization    randomized, controlled trials with better baselines.
           areas, also seen in high-grade lesions. Recent studies point
           to an increase of EOR and GTR, but without increasing of   Future technologies
           the overall survival rate.  After review, 5-ALA had 91%   Neuronavigation  has  become  more  popular  and  the
                               [64]
           sensitivity, 59% specificity, 85%  PPV, and 71% negative   localization  of tumors has come to practice  with the
           predictive  value  for  histopathological  identification  of   navigation instrument and the monitor. Even  though, what
           malignant glioma.   Future  objectives  in  fluorescence   if we had the images seen in the surgical field continuously,
                           [65]
           guidance  may  lead  to  better  microscopic  visualization   without  navigators?  The  augmented  reality  has  come  to
           methods for the fluorescein such as filters, special masks   time with the objective of sending information to surgical
           or lens. [66]                                      field without monitors.

           Current evidences                                  Augmented reality technique has four steps: virtual image
           The  Cochrane  group  has  reviewed  all  the  reports  of   creation;  real  environment;  projection  and  registration.
           image-guided  surgery  for brain  tumor  resection  and   Thus, image can be seen in the surgical field and the virtual
           found some issues. Most of the studies are not controlled   interface can be used. The augmented reality is important
           and  randomized;  also  patients’ baselines  and  tumor   in planning surgery and having the lesion visible in the skin
           aspects were heterogeneous in most of the groups and the   since the beginning of the surgery. The augmented reality
           resecability  of  them  was  different  between  intervention   can be applied not only to the surgical field to prepare a
           and control groups.  Despite limitations and low quality   better  surgical  incision and approach,  but also to the
                           [2]
           of evidence, the analyses from the classical reports from   surgical view in the microscope, which is important when
           Senft 2011, Stummer 2006 and Wu 2007 showed a trend   the surgeon cannot take his or her eyes/instruments  from
           for better results.  Complete tumor resection was achieved   the  microscopic field. [67,68]
                         [2]
           with iMRI in 23/24 (96%) of participants in the intervention
           arm group compared with 17/25 (68%) of participants in   Moreover, the augmented reality could also include other
           the control arm (relative risk [RR] for incomplete resection   parameters such as fiber tracts or important structures that
           0.13, 95% confidence interval [CI]: 0.02-0.96, low quality   should not be approached. As an innovation in neurosurgical
           evidence). [2]                                     surgery, there are few studies but promising applications. [67]

           Using 5-ALA, complete resection was performed in 90/139   Also other interesting  concept  is the regional  vs. global
           (65%)  of  the  intervention  arm  vs.  47/131  (36%)  of  the   DTI biomarkers for glioblastoma. Most of this lesions are
           control  arm  (RR  for  incomplete  resection  0.55,  95%  CI:   heterogeneous with multiple histological features and can
           0.42-0.71, low quality evidence). Finally, neuronavigation   lead to different degrees of malignancy, thus biopsies can be
           with  DTI  was  achieved  among  the  85  participants  with   different in multiple areas. DTI is routinely used to locate
           high-grade  glioma and complete tumour resections  were   high-grade areas, but the development of a sensitive and
           achieved in 32/42 in the DTI arm vs. 14/43 in the control   specific biomarker, remains an issue. Also, the role of DTI-
           arm (RR for incomplete resection 0.35, 95% CI: 0.20-0.63,   derived tensor metrics in normal brain and infiltrated brain
           very low quality evidence). Among 129 participants with   is important for the distinction of tumor infiltration in non-
           LGG, complete tumor resections were achieved in 40/61   contrast-enhanced areas. As the GBM been considered as a
           in  the DTI arm vs. 42/68 in the control arm (no significant   whole brain disease, DTI analysis of the whole brain might
           difference).  In survival analysis, the 5-ALA groups had   be  more  interesting  than  studying  just  the  lesion  areas.
                    [2]
           a median survival of 15.2 months (95% CI: 12.9-17.5) in   Roldán-Valadéz et al. showed that relative anisotropy, axial
           intervention  group  and  control  with  13.5  months  (95%   diffusivity (AD), Cl (linear tensor), Cs (spherical tensor),
           CI:  12.0-14.7).  The  neuronavigation-DTI  arm  was  21.2   were  important for regional DTI tumor analysis.  Also,
                                                                                                      [69]
           months (95% CI: 14.1-28.3) vs. 14.0 months (95% CI: 10.2-  Cortez-Conradis pointed for AD, Cl, Cs and introduced the
           17.8). Only in World Health Organization grade IV tumors    whole brain concept. The advantages of whole brain DTI
           analysis, neuronavigation-DTI arm was 19.3 months (95%   analysis are: Decrease of bias associated with the analysis
           CI: 15.2-23.5) vs. 11.1 months (95% CI: 7.3-15.2) in the   of just one region of interest; the tumor and edema regions
           control arm.  In time to progression, the median time  in   are included; lesions not perceived by the radiologist’s eye
                     [2]
           iMRI group was 226 days (95% CI: 0.0-454) vs. 154 days   on conventional sequences would be included in a global
           (95%  CI:  60-248)  in  control.  With  5-ALA,  it  was  5.1   assessment; it may avoid problems associated with partial
           months (95% CI: 3.4-6.0) vs. 3.6 months (3.2-4.4 months)   volume  effects,  and  inaccurate  image  coregistrations.
                                                                                                           [70]
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                                                                                                                      Journal of Cancer Metastasis and Treatment ¦ Volume 2 ¦ March 11, 2016 ¦
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