Magnetic Resonance Diffusion Kurtosis Imaging In Assessment Of Gastric Cancer Aggressiveness

Objective:To explore the potential associations between parameters derived from magnetic resonance(MR)diffusion kurtosis imaging(DKI)and the aggressiveness of gastric cancers.Materials and Methods:Forty-nine patients with gastric cancers were enrolled in this prospective study.All patients underwent MR examination before surgery.All MR images were reviewed by 2 radiologists using software IDL 6.3 and a region of interest was manually drawn on the specific slice showing the largest area of tumor.Three parameters were calculated automatically:apparent diffusion coefficient(ADC),corrected diffusion coefficient(D)and excess diffusion kurtosis coefficient(K).All statistical analyses were performed with SPSS(version 22.0).A two-tailed P value less than 0.05 was considered statistically significant.Shapiro-Wilk tests were used to check normality assumption for all parameters in all groups.Correlations between DKI parameters with T stage,N stage,overall stage,differentiation degree and Lauren classification of gastric cancers were evaluated with Spearman correlation test.One-way analysis of variance was used to detect the differences of DKI parameters among gastric cancers with different N stages and Lauren types while independent samples t test was used to compare DKI parameters between gastric cancers with different T stages(Tl-2 vs T3-4),overall stages(I-II vs III-IV),differentiation degrees(poorly/moderate-poorly vs moderately/well),lymph nodes metastasis(N+ vs N-),vascular invasion(present vs absent)and perineural invasion(present vs absent).Diagnostic performance of DKI parameters in differentiating gastric cancers with different pathological characteristics was tested with receiver operating characteristic(ROC)curve analysis.Results:ADC value showed negative correlations with T stage,differentiation degree and Lauren classification while K value positively correlated with T stage,overall stage,differentiation degree and Lauren classification of gastric cancers,but D value showed no significant correlations with any pathological characteristics.For differentiating gastric cancers with specific pathological characteristics,three DKI parameters showed different performances.ADC,D and K values performed well in differentiating between gastric cancers of T1-2 with T3-4(area under ROC curve(AUC)= 0.798,0.745 and 0.804,respectively);ADC and D values showed good performances on identifying gastric cancers with and without lymph nodes metastasis(AUC = 0.741 and 0.729);ADC and K values could help differentiate poorly/moderate-poorly differentiated gastric cancers from moderately/well differentiated ones(AUC = 0.732 and 0.794,respectively)and differentiate intestinal type gastric cancers from mixed/diffuse type ones(AUC = 0.678 and 0.755,respectively).No significant differences were found for DKI parameters among different status of vascular invasion and perineural invasion.Conclusion:DKI derived parameters might be helpful in preoperative assessment of gastric cancer aggressiveness,especially in identifying gastric cancers with different T stages,differentiation degrees and Lauren types,and in predicting the presence of lymph nodes metastasis.