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

Abstract

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. 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 (Ktrans) between blood plasma and extravascular extracellular space), Kep (rate between extravascular extracellular space and blood plasma), Ve (extravascular volume fraction), Vp (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 <0.05 indicated a statistically significant difference. The study included 75 males and 22 females with a median age of 58.8 years (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 Ktrans (r = 0.533; p < 0.001), and relatively weak correlations between D* and Ktrans (r = 0.389; p < 0.001), D* and Vp (r = 0.442; p < 0.001), f·D* and Vp (r = 0.466; p < 0.001), and f and Vp (r = -0.234; p = 0.021). IVIM perfusion-related parameters, especially f·D*, demonstrated moderate correlations with DCE-MRI quantitative parameters in rectal cancer.