Glioma grading and IDH1 mutational status: assessment by intravoxel incoherent motion MRI

To assess the diagnostic performance of intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) in differentiating high-grade gliomas (HGGs) from low-grade gliomas (LGGs), and predicting the isocitrate dehydrogenase 1 (IDH1) mutational status.

IVIM imaging was performed preoperatively in 42 patients with gliomas using 10 b-values (0-1,200 s/mm²) in a 3 T MRI machine. The perfusion fraction (f), true diffusion coefficient (D), pseudo-diffusion coefficient (D*), and apparent diffusion coefficient (ADC) were calculated within the tumours and in the contralateral normal white matter, and the values were compared between the HGGs and LGGs, and between IDH1 wild-type and mutated-type gliomas. In addition, the receiver operating characteristic (ROC) was also analysed.

When compared to LGGs, HGGs had lower ADC (0.989×10^-3 versus 1.243×10^-3 mm²/s, p<0.001), smaller D (0.849×10^-3 versus 1.062×10^-3 mm²/s, p=0.001), larger D* (9.731×10^-3 versus 5.442×10^-3 mm²/s, p=0.006), and bigger f-values (0.204 versus 0.130, p<0.001) within the tumours. The area under the receiver operating characteristic (ROC) curve (AUC) was 0.937, 0.898, 0.770, and 0.838, respectively. Among the LGGs, tumours with the IDH1 mutation had a higher ADC (1.286×10^-3 mm²/s), when compared to the wild-type IDH1 (1.122×10^-3 mm²/s, p=0.003), with an AUC of 0.936. In HGGs, tumours with the IDH1 mutation had higher ADC (1.056×1010^-3 versus 0.946×10^-3 mm²/s, p=0.030), smaller D* (6.204×10^-3 versus 11.999×10^-3 mm²/s, p=0.023) and smaller f-values (0.143 versus 0.244, p<0.001), with an AUC of 0.766, 0.841 and 0.992, respectively.

Glioma grading can be differentiated and IDH1 mutational status can be predicted using IVIM.