Abstract
BACKGROUND: Determining isocitrate dehydrogenase (IDH) mutation is crucial for glioma management. Slow diffusion coefficient (SDC) is a novel metric being proposed to measure in vivo tissue slow diffusion. In its basic form, SDC is derived from a high b-value diffusion-weighted image and a higher b-value diffusion-weighted image. The study attempts to distinguish IDH genotypes of diffuse gliomas using SDC alone and in combination with other two diffusion metrics of diffusion-derived vessel density (DDVD) and apparent diffusion coefficient (ADC). METHODS: This study enrolled 63 patients with diffuse gliomas (30 IDH-mutant and 33 IDH-wildtype) who underwent diffusion-weighted imaging at 3T. SDC was calculated with b = 500 and 750 mm(2)/s images. DDVD was calculated with b = 0 and 10 mm(2)/s images. ADC was calculated with b = 0 and 1000 mm(2)/s images. Correlations between the diffusion metrics and IDH genotypes were studied, as well as the correlation between SDC and Ki-67 expression. RESULTS: There was a significant difference among three histological grading of glioma (median value: 0.472 au/s for grade-2, 0.441 au/s for grade-3, 0.364 au/s for grade-4, p < 0.0001). Based on IDH gene testing, IDH mutant negative tumors had SDC value of 0.339 ± 0.055 au/s, IDH mutant positive tumors had SDC value of 0.437 ± 0.097 au/s, with AUROC of 0.828 for separation. SDC was negatively and weakly correlated with DDVD, with Pearson r of -0.212 (p = 0.096). A combination of SDC and DDVD separated IDH mutant -/+ tumors with an AUROC of 0.886. SDC was positively and moderately correlated with ADC, with Pearson r of 0.705 (p < 0.0001). AUROC analysis shows a combination of SDC, DDVD, and ADC separated IDH mutant -/+ tumors with an AUC of 0.897. If immunohistochemistry IDH partially positive tumors were not included, a combination of SDC, DDVD and ADC separated immunohistochemistry IDH mutant -/+ tumors with an AUC of 0.911. SDC was negatively and moderately correlated with Ki 67 LI, with Pearson r of -0.382 (p = 0.002). CONCLUSION: SDC can help to distinguish IDH genotypes in diffuse gliomas. A combination of SDC and DDVD, or a combination of SDC, DDVD, and ADC, can further improve disease classification. CLINICAL TRIAL NUMBER: Not applicable.