BACKGROUND AND PURPOSE

Molecular glioblastomas are challenging to distinguish from lower-grade diffuse astrocytomas (grades 2-3) without T2/T2 FLAIR mismatch, when assessed on T1-gadolinium and T2/T2 FLAIR MRI. This study aimed to evaluate the performance of the ADC from diffusion-weighted imaging and the relative CBV from DSC perfusion imaging in differentiating molecular glioblastomas from lower-grade diffuse astrocytomas.

MATERIALS AND METHODS

Fourteen patients with molecular glioblastomas (defined as isocitrate dehydrogenase wildtype (IDH-wt), exhibiting one or more of the following: telomerase reverse transcriptase (TERT) promoter mutation, epidermal growth factor receptor (EGFR) gene amplification, or +7/-10 chromosomal alterations, but without microvascular proliferation or necrosis) and thirteen patients with lower-grade diffuse astrocytomas (IDH-mutated or not elsewhere classified, grades 2-3) were included. ADC values and DSC-rCBV values were measured, and the two groups were compared using T‑test and Wilcoxon rank-sum test. Combinations of variables and tumor characteristics were analyzed using binary logistic regression, receiver operating curve (ROC) analysis, and Firth regression model.

RESULTS

Molecular glioblastomas exhibited lower minimum ADC, mean ADC (p < 0.01), maximum ADC (p < 0.05) and higher standard deviation of ADC (p < 0.05), compared to lower-grade astrocytomas, measured in a 7 mm ROI in the lowest ADC region. Molecular glioblastoma also had higher normalized median, average, and minimum rCBV ratios (p < 0.01) in a 10 mm ROI in the highest perfused region. A combined receiver operating curve (ROC) model of ADC and rCBV achieved an area under the curve (AUC) of 0.93 (95% CI: 0.82-1.00).

CONCLUSIONS

This study demonstrates that ADC and rCBV measurements can help differentiate molecular glioblastomas from lower-grade diffuse astrocytomas lacking T2/T2 FLAIR mismatch. These findings may aid in preoperative tumor characterization, surgical planning, and prognosis.