The value of vessel size imaging of microvasculature in grading of oligodendroglioma

Objective: To investigate the value of vessel size index(VSI) in grading oligodendroglioma by vessel size imaging technique. Methods : Twenty-four histologically confirmed oligodendroglioma cases were enrolled (13 grade II and 11 grade III). All patients underwent conventional MRI scanning, followed by multi gradient-echo spin-echo sequence from dynamic susceptibility contrast perfusion to generate VSI maps. Region of interests were contoured on VSI color maps to obtain hot-spot value of mean VSI of microvasculature (VSI_mean) and maximum VSI of microvasculature (VSI_max). Paraffin sections of each case was stained with CD34 to acquire microvascular caliber (VS_his). Pearson correlation analysis was used to evaluate the correlation between VSI_mean, VSI_max and VS_his respectively. Mann-Whitney U test was used to compare VSI_mean, VSI_max and VS_his between grade II and III oligodendroglioma. ROC analysis was performed to assess the effectiveness of VSI_mean, VSI_max and VS_his in grading oligodendroglioma. Results: Both VSI_mean and VSI_max were strongly correlated with VS_his (r = 0.738, 0.705, P < 0.05). For grade II and III oligodendroglioma, VSI_mean were 38.93(17.96 to 81.18) μm and 91.49(36.94 to 144.68) μm, VSI_max were 45.12(22.30 to 89.65) μm and 121.19(57.29 to 164.00) μm, VS_his were 8.51(5.25 to 12.76) μm and 11.03(7.59 to 21.96) μm respectively. VSI_mean, VSI_max, and VS_his showed significant difference (Z = -3.505, -3.911, -2.729, P < 0.05) between grade II and III oligodendroglioma. ROC analysis revealed that the optimal cutoff value, sensitivity, specificity and AUC of VSI_mean was 52.58 μm, 90.91%, 92.31%, 0.923 respectively, 81.18 μm, 90.91%, 100.00%, 0.972 for VSI_max, and 9.01 μm, 90.00%, 84.62%, 0.838 for VS_his respectively. Conclusions: Vessel size imaging derived VSI correlated well with histopathology. It could provide valuable information in the pre-operative grading of oligodendroglioma. (authors)