Study on Neuroepithelial Tumor Grading and Pseudoprogression After Glioma Therapy Using Advanced Functional MRI Techniques
Study on Neuroepithelial Tumor Grading and Pseudoprogression After Glioma Therapy Using Advanced Functional MRI Techniques
Contrast-enhanced MRI is the most common way for evaluating neuroepithelial tumor grading and
 monitoring for tumor recurrence,but the ability to predict tumor behavior remains very
 limited.In this study, the investigators will use multi-b-value diffusion-weighted
 imaging(DWI),three-dimensional arterial spin labeling(3D-ASL) and dynamic contrast-enhanced
 MRI imaging(DCE) to evaluate neuroepithelial tumor grading and monitor for tumor recurrence.
Glioma is classified into 4 grades, with worse prognosis for more advanced grades.Previous
 studies have suggested that different therapeutic strategies should be applied for gliomas at
 different grades,so glioma grading before the operation is therefore of important clinical
 significance for guiding the grade-dependent therapeutic strategy.

 Combination temozolomide and radiation significantly prolongs survival compared with
 radiation alone and has become standard treatment for Patients with high-grade glioma.
 Response assessment in these patients is difficult as a result of the frequent occurrence of
 early imaging changes indistinguishable from tumor progression, termed pseudoprogression. The
 majority of patients remain clinically stable. It is often unclear whether current therapy
 should be maintained or second-line therapy initiated.

 The ADC value can potentially reveal the differences in cellularity and nuclear atypia of
 gliomas1. Theoretically, high cellularity in advanced gliomas may impede free water diffusion
 and thus lead to a decreased ADC value.In several previous studies,recurrent tumors have
 shows significantly higher cellularity than those shown by pseudoprogression.Such high
 cellularity is associated with relative reductions in extracellular space when compared with
 low cellularity, resulting in decreased diffusivity of water molecules in the former
 circumstance when compared with the latter. DWI measures the degree of water diffusion within
 tissue Apparent diffusion coefficient (ADC) values quantify the mobility of water molecules
 at the cellular level, holding the potential to differentiate between necrosis, edema and
 recurrent tumor.

 A potential mechanism of pseudoprogression is that radiation-induced vascular changes may
 lead to focal transient increase in gadolinium enhancement.Three-dimensional arterial spin
 labeling(3D-ASL) and dynamic contrast-enhanced (DCE) MRI imaging provides a noninvasive means
 for quantifying tumor vascular properties.
Inclusion Criteria:

 -  Among the patients with high-grade glioma (glioblastoma multiforme or anaplastic
 astrocytoma), who received concurrent chemoradiation (CCRT) with temozolomide, the
 patients show the measurable enhancing portion (1 cm in the long diameter according to
 the RANO criteria) in the immediate f/up MRI after CCRT.

 Exclusion Criteria:

 -  Among the patients with high-grade glioma (glioblastoma multiforme or anaplastic
 astrocytoma), who received concurrent chemoradiation (CCRT) with temozolomide, the
 patients do not show the measurable enhancing portion (1 cm in the long diameter
 according to the RANO criteria) in the immediate f/up MRI after CCRT.