Concluding remarks
As discussed above, the differentiation between GBM recurrence and
radiation necrosis remains a crucial challenge (Fig. 1), given that the
need for additional surgery in a previously operated brain region
increases surgical risk in addition to raising treatment costs. An
important current tool is multiparametric MRI using a combination of
perfusion and diffusion parameters. Although previous studies
[85-91] had found that apparent diffusion coefficient, volume
transfer constant, and relative cerebral blood volume are very useful,
and the latter is the strongest parameter for differentiating radiation
necrosis from GBM tumors [92]. Nael et al. [93] achieved a
diagnostic accuracy of 92.8% by combining the use of volume transfer
constant and relative cerebral blood volume.
In daily neuro-oncological practice, multiparametric MRI is the most
used tool to achieve an accurate differential diagnosis between GBM,
inflamed sites, and other brain diseases. Despite its advantages, the
use of PET Scan remains limited in many regions of the world due to
economical and logistic shortcomes. Overall, the integrated use of
different MR and PET approaches, including multiparametric MRI, in
addition to perfusion and diffusion parameters [94] may enable
increasingly accurate diagnosis based on brain imaging.