Application of ²³ Na MRI at 7 Tesla in distinguishing IDH genotype, P53 phenotype, and Ki‐67 LI in adult‐type diffuse gliomas

Abstract Background : The diagnostic performance of ultra‐high‐field 23 Na magnetic resonance imaging (MRI) in predicting the P53 phenotype and Ki‐67 labeling index (LI) in adult‐type diffuse gliomas is still unknown. No studies have compared its diagnostic efficacy with diffusion weighted imaging (DWI) for distinguishing isocitrate dehydrogenase (IDH) genotype, Ki‐67 LI, and P53 phenotype. Purpose : To determine whether 23 Na MRI at 7 Tesla (7T) field can accurately predict IDH genotype, P53 phenotype, and Ki‐67 LI in adult‐type diffuse gliomas and compare efficacy of 23 Na MRI with that of DWI. Materials and Methods : Thirty‐six glioma patients underwent preoperative 23 Na MRI on a 7T scanner (Siemens Healthcare). Total sodium concentration (TSC), relative TSC (rTSC), apparent diffusion coefficient (ADC), and relative ADC (rADC) were acquired. ANOVA was used to compare differences in TSC, rTSC, ADC, and rADC within groups. Receiver operating characteristic curves and area under the curves (AUCs) were used to evaluate diagnostic performance. Results : TSC and rTSC of IDH mutant‐type, P53 mutant‐type, and high Ki‐67 LI were higher than that of IDH wild‐type, P53 wild‐type, and low Ki‐67 LI, respectively ( p = .025, <.001, .009, .012, <.001, and <.001). rTSC had highest diagnostic efficacy for distinguishing different IDH genotype (AUC = 0.837), for distinguishing gliomas with different P53 phenotype (AUC = 0.750) and for distinguishing gliomas with different Ki‐67 LI (AUC = 0.862). Conclusions : 7T 23 Na MRI can non‐invasively distinguish adult‐type diffuse gliomas with different IDH genotype, P53 phenotype, and Ki‐67 LI. Compared with DWI (0 and 1000 s/mm 2 ), 7T 23 Na MRI can have superior diagnostic performance.