ABSTRACT
Objective:To investigate the value of intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) and texture analysis for predicting BRAF gene mutation in rectal cancer.Methods:The clinical diagnositic trial was conducted. The clinicopathological data of 36 rectal cancer patients who were admitted to the First People's Hospital of Shangqiu from January 2016 to June 2021 were collected. There were 28 males and 8 females, aged (50±4)years. All the 36 patients were confirmed by pathological examination. After genetic testing, 12 patients with BRAF mutant type of BRAF V600E mutation were allocated into the mutation group, and 24 patients with BRAF wild type were allocated into the non-mutation group. All patients underwent MRI scan before surgery, and IVIM related post-processing images were received by Function Tool post-processing software. Observation indicators: (1) consistency test between observers of IVIM para-meters and texture parameters; (2) comparison of IVIM parameters on MRI between the two groups; (3) comparison of texture parameters on MRI between the two groups; (4) diagnostic efficacy of IVIM and texture parameters. The intraclass correlation coefficient (ICC) was used to evaluate the consistency between observers, with ICC >0.80 as good consistency. The average values of para-meters with ICC >0.80 were included for further analysis. Measurement data with normal distribu-tion were represented as Mean± SD, and comparison between groups was analyzed by the indepen-dent sample t test. Measurement data with skewed distribution were represented as M( Q1, Q3), and comparison between groups was analyzed using the Mann-Whitney U test. Count data were described as absolute numbers, and comparison between groups was analyzed by the chi-square test. Comparison of ordinal data was analyzed by the non-parameter rank sum test. The texture parameters were combined using the Logistic regression model. Receiver operating charac-teristic curve was used to analyze the predictive performance and calculate the sensitivity and specificity. Results:(1) Consistency test between observers of IVIM parameters and texture parameters: the ICCs between two observers of IVIM parameters including apparent diffusion coefficient, diffusion related coefficient, perfusion-related diffusion coefficient and perfusion-related parameter were 0.91, 0.90, 0.91, 0.89, respectively. The ICCs of texture parameters including the minimum value, the maximum value, the 10th percentile and the 25th percentile between two observers were <0.80 while the ICCs of texture parameters including mean value, the 50th percentile, the 75th percentile, the 90th percentile, energy, entropy, skewness and kurtosis between two observers were >0.80. (2) Comparison of IVIM parameters on MRI between the two groups: IVIM parameters of diffusion related coefficient and perfusion-related parameter on MRI were (0.70±0.13)×10 -3 mm 2/s and 0.39±0.30 for the mutation group, versus (0.79±0.12)×10 -3 mm 2/s and 0.17±0.10 for the non-mutation group, showing significant differences between the two groups ( t=-2.17, 2.46, P<0.05). (3) Comparison of texture parameters on MRI between the two groups: the texture parameters of mean value and energy on diffusion related coefficient image were 0.54±0.23 and 0.00(0.00,0.01) for the mutation group, versus 0.77±0.34 and 0.01(0.00,0.01) for the non-mutation group, showing significant differences between the two groups ( t=-2.12, Z=-1.35, P<0.05). (4) Diagnostic efficacy of IVIM and texture parameters: the areas under the curve (AUCs) of diffusion related coefficient, perfusion-related parameter, IVIM parameters combination, mean value of diffu-sion related coefficient image, energy value of diffusion related coefficient image, texture parameters combination were 0.69[95% confidence interval ( CI) as 0.52-0.84], 0.76(95% CI as 0.59-0.88), 0.79(95% CI as 0.62-0.91), 0.71(95% CI as 0.52-0.85), 0.79(95% CI as 0.62-0.91), 0.84(95% CI as 0.68-0.94), which were all lower than the AUC of IVIM and texture parameters combination as 0.92(95% CI as 0.79-0.99). Conclusions:IVIM parameters and texture parameters of MRI can non-invasively predict the mutation status of BRAF gene in rectal cancer. The combination of IVIM and texture parameters has a better predictive efficacy.