Correlations between DWI, IVIM, and HIF-1 alpha expression based on MRI and pathology in a murine model of rhabdomyosarcoma

Purpose: To investigate the correlation between DWI, intravoxel incoherent motion (IVIM), and hypoxia-inducible factor 1-alpha (HIF-1 alpha) expression in a nude mouse model of rhabdomyosarcoma based on imaging and pathological comparisons. Methods: Human rhabdomyosarcoma-derived (RD) cells were inoculated into the right thigh muscle of 20 BALB/c female nude mice. Mice were imaged using 3.0 Tesla MRI system. T-1-weighted imaging, T-2-weighted imaging, DWI, and IVIM images were obtained. ADW4.7 (GE Healthcare, ChicagoAQ34, IL, USA) was used for image processing of ADC, D-slow, D-fast, and f values. All parameter values were independently analyzed by 2 observers. Immunohistochemistry of HIF-1 alpha was performed. We used a specific image-pathology comparison method to ensure correct overlap between the image plane and the pathological section. Mann-Whitney U test or independent sample t test, Pearson or Spearman correlation test, the intragroup correlation coefficient, Kolmogorov-Smirnov test, and receiver operating characteristic curve were used. The correlation between DWI and intravoxel incoherent motion parameter values and HIF-1 alpha expression was determined. Results: There were 10 mice in the low-expression group and 7 in the high-expression group. The ADC and D-slow values were negatively correlated with HIF-1 alpha with correlation coefficients of -0.491 and - 0.702 (P = 0.045 and 0.002). The f value positively correlated with HIF-1 alpha expression (r = 0.485, P = 0.048). ADC, D-slow and f were significantly different between the high-HIF-1 alpha expression tumors and the low-HIF-1 alpha expression tumors. ADC showed the best predictive performance among all parameters (area under the curve = 0.652, sensitivity = 83.3%, specificity = 63.6%). Conclusion: The parameter values of DWI and intravoxel incoherent motion can be used to evaluate the expression of HIF-1 alpha in rhabdomyosarcoma. ADC, D-slow, and f value showed correlation with the expression of HIF-1 alpha.