Diffusion-weighted multiparametric MRI for monitoring longitudinal changes of parameters in rabbit VX2 liver tumors.

Abstract

To investigate the value of different quantitative models of diffusion-weighted multiparametric imaging (DW-MPI) including traditional as well as several advanced models for monitoring the longitudinal parameter changes in rabbit liver VX2 carcinoma and for correlating the perfusion-related imaging parameters to vascularity of tumor tissue. Rabbit liver VX2 carcinoma was imaged by DW-MPI at the 2nd, 3rd, and 4th weeks after tumor implantation at 1.5T using two sets of b values ranging from 0 to 2000 s/mm(2) . Serial parameter changes of each model at three timepoints were compared. Univariate and multivariate regression analyses were carried out to analyze the ability of perfusion-related parameters, including apparent diffusion coefficient (ADC), perfusion fraction (f), and pseudodiffusion coefficient (D*), to predict mean microvessel density (MVD) as determined by quantitative histopathology. For the period from Week 2 to Week 4, the measurements of ADC, f, and KDKI illustrated a statistical difference (P = 0.000, P = 0.000, and P = 0.002, respectively), whereas the comparison of D, D*, DDKI , DSEM , and αSEM demonstrated no statistical significance. ADC and f showed highest correlation with MVD at Week 4 (r(2) = 0.307, P = 0.017, and r(2) = 0.402, P < 0.01, respectively). Multivariate analyses confirmed highest correlation of f and ADC with MVD at Week 4 (P = 0.001 and P = 0.002). ADC, f, and KDKI were identified as the most promising parameters for monitoring changes in rabbit liver VX2 carcinoma and f and ADC showed highest correlation with MVD. J. Magn. Reson. Imaging 2016;44:707-714.