Application of Volumetric Analysis to Glioblastomas: a Correlation Study on the Status of the Isocitrate Dehydrogenase Mutation

ABSTRACT

PURPOSE: To investigate whether volumetric analysis based on T2WI and contrast-enhanced (CE) T1WI can distinguish between isocitrate dehydrogenase-1 mutation-positive (IDH1(P)) and -negative (IDH1(N)) glioblastomas (GBMs). MATERIALS AND METHODS: We retrospectively enrolled 109 patients with histopathologically proven GBMs after surgery or stereotactic biopsy and preoperative MR imaging. We measured the whole-tumor volume in each patient using a semiautomatic segmentation method based on both T2WI and CE T1WI. We compared the tumor volumes between IDH1(P) (n = 12) and IDH1(N) (n = 97) GBMs using an unpaired t-test. In addition, we performed receiver operating characteristic (ROC) analysis for the differentiation of IDH1(P) and IDH1(N) GBMs using the tumor volumes based on T2WI and CE T1WI. RESULTS: The mean tumor volume based on T2WI was larger for IDH1(P) GBMs than IDH1(N) GBMs (108.8 +/- 68.1 and 59.3 +/- 37.3 mm3, respectively, P = 0.0002). In addition, IDH1(P) GBMs had a larger tumor volume on CE T1WI than did IDH1(N) tumors (49.00 +/- 40.14 and 22.53 +/- 17.51 mm3, respectively, P < 0.0001). ROC analysis revealed that the tumor volume based on T2WI could distinguish IDH1(P) from IDH1(N) with a cutoff value of 90.25 (P < 0.05) 7 of 12 IDH1(P) (58.3%) and 79 of 97 IDH1(N) (81.4%). CONCLUSION: Volumetric analysis of T2WI and CE T1WI could enable IDH1(P) GBMs to be distinguished from IDH1(N) GBMs. We assumed that secondary GBMs with IDH1(P) underwent stepwise progression and were more infiltrative than those with IDH1(N), which might have resulted in the differences in tumor volume.