Intravoxel Incoherent Motion Parameters for Assessing the Efficiency of Locoregional Bridging Treatments before Liver Transplantation

Abstract

Objective. To evaluate the diagnostic accuracy of Intravoxel Incoherent Motion (IVIM) parameters for assessment of tumor response after locoregional treatment (LRT) of hepatocellular carcinoma (HCC). Methods. Fifteen patients with HCC who had undergone LRTs (11 transarterial radioembolization, 4 transarterial chemoembolization) were included. in addition to routine upper abdominal magnetic resonance imaging sequences, IVIM with 16 different b values and conventional diffusion weighted imaging with 3 different b factors were obtained immediately before and 8 weeks after LRTs. Magnetic resonance imaging response was evaluated according to modified Response Evaluation Criteria in Solid Tumors (mRECIST) and HCCs were categorized into 2 subgroups, responders and nonresponders. Quantitatively, the number of diffusion-changes were calculated with apparent diffusion coefficient (ADC) and IVIM parameters, including mean D (true diffusion coefficient), pseudo-diffusion coefficient associated with blood flow, and f (perfusion fraction) values. Subsequently, the pre- and post-treatment parameters were compared using the Mann-Whitney U test. Results. Considering all HCCs, a significant decrease was observed according to mRECIST criteria (-38.43 +/- 16.49). the ADC and D values after LRTs were significantly higher than those of the preceding ones. the f values after LRTs were significantly lower than those of pre-treatment. in the responders group, ADC and D values were significantly increased and f values were significantly decreased after LRTs. No difference of statistical significance was achieved in the nonresponders group. Conclusions. ADC values and IVIM parameters appear to reflect the response of LRTs as effectively as those of mRECIST. This promises new horizons in the management of pretransplant patients, especially in renal insufficiency clinical settings, owing to the elimination of contrast media administration.