Correlation Between Intravoxel Incoherent Motion and Dynamic Contrast-Enhanced Magnetic Resonance Imaging Parameters in Rectal Cancer

Rationale and Objectives This study aimed to determine the correlation between intravoxel incoherent motion (IVIM) and multiphase dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) quantitative parameters in patients with rectal cancer. Materials and Methods Ninety-seven patients with rectal cancer were included in this study. All pelvic MRI examinations were performed in a 3.0 T MR unit, including diffusion-weighted imaging with 16 b values, DCE-MRI with two different flip angles (5° and 10°, respectively), and T1-fast field echo sequences as the reference. The IVIM perfusion-related parameters ( f , perfusion fraction; D* , pseudo-diffusion coefficient; f·D* , the multiplication of the two parameters) were calculated by biexponential analysis. Quantitative DCE-MRI parameters were transfer constant ( K trans ) between blood plasma and extravascular extracellular space), K ep (rate between extravascular extracellular space and blood plasma), V e (extravascular volume fraction), V p (plasma volume fraction), and area under the gadolinium concentration curve. Interobserver agreements were evaluated using the intraclass correlation coefficient and Bland–Altman analysis. A p value Results The study included 75 males and 22 females with a median age of 58.8years (range, 26–85years). Interobserver reproducibility for IVIM perfusion-related parameters and DCE-MRI quantitative parameters was good to excellent (intraclass correlation coefficient = 0.8618–0.9181, intraclass correlation coefficient = 0.7826–0.9088, respectively). Moderate correlations were found between f·D* and K trans ( r  = 0.533; p D* and K trans ( r  = 0.389; p D* and V p ( r  = 0.442; p f·D* and V p ( r  = 0.466; p f and V p ( r = −0.234; p  = 0.021). Conclusion IVIM perfusion-related parameters, especially f·D* , demonstrated moderate correlations with DCE-MRI quantitative parameters in rectal cancer.