Diagnostic role of apparent diffusion coefficient combined with intratumoral susceptibility signals in differentiating high-grade gliomas from brain metastases

Objective: The aim of this study was to assess whether tumoral and peritumoral apparent diffusion coefficient values and intratumoral susceptibility signals on susceptibility-weighted imaging could distinguish between high-grade gliomas and brain metastases, and to investigate their associations with the Ki-67 proliferation index. Materials and methods: Fifty-seven patients with pathologically confirmed diagnoses of either high-grade glioma or brain metastasis were enrolled in this study (23 with high-grade gliomas and 34 with brain metastases). The minimum and mean apparent diffusion coefficients in the enhancing tumoral region (ADC(min) and ADC(mean)) and the minimum apparent diffusion coefficient in the peritumoral region (ADC(edema)) were measured from apparent diffusion coefficient maps, and intratumoral susceptibility signal grades acquired by susceptibility-weighted imaging were calculated. Ki-67 proliferation index values were obtained from the hospital database. These parameters were evaluated using the Mann-Whitney U test, independent-sample Hest, Spearman correlation analysis, receiver operating characteristic curve, and logistic regression analyses. Results: ADC(mean) ADC(min) values, and intratumoral susceptibility signal grades in brain metastases were significantly lower than those in high-grade gliomas (all p< 0.05). Ki-67 proliferation index values showed significant correlations with ADC(mean )ADC(min), and intratumoral susceptibility signal grade in brain metastases (all p< 0.05), but no correlation was found in high-grade gliomas (all p> 0.05). According to receiver operating characteristic curve analysis, ADC(mean) achieved the highest diagnostic performance for discriminating high-grade gliomas from brain metastases. Furthermore, the combination of tumoral apparent diffusion coefficient parameters with intratumoral susceptibility signal grade provided a higher area under the curve than univariate parameters. Conclusion: The combination of tumoral apparent diffusion coefficient with intratumoral susceptibility signal grade can offer better diagnostic performances for differential diagnosis. Apparent diffusion coefficient and intratumoral susceptibility signal may reflect cellular proliferative activity in brain metastases, but not in high-grade gliomas.