Evaluation of Effects of TGF‐β1 Inhibition on Gastric Cancer in Nude Mice by Diffusion Kurtosis Imaging and In‐Line X‐ray Phase Contrast Imaging With Sequential Histology

BACKGROUND: Accurate and complete response evaluation after treatment is important to implement individualized therapy for gastric cancer. PURPOSE: To investigate the effectiveness of diffusion kurtosis imaging (DKI) and in‐line X‐ray phase contrast imaging (ILXPCI) in the assessment of the therapeutic efficacy by transforming growth factor beta 1 (TGF‐β1) inhibition. STUDY TYPE: Prospective animal study. ANIMAL MODEL: Thirty nude mice subcutaneous xenotransplantation tumor model of gastric cancer for DKI and 10 peritoneal metastasis nude mice model for ILXPCI. FIELD STRENGTH/SEQUENCE: Examinations before and serially at 7, 14, 21, and 28 days after TGF‐β1 inhibition treatment were performed at 3T MRI including T(2)‐weighted imaging (T(2)WI) and DKI with five b values of 0, 500, 1000, 1500, 2000 s/mm(2); ILXPCI examinations were performed at 14 days after treatment. ASSESSMENT: DKI parameters (apparent diffusion coefficient [ADC], diffusivity [D] and kurtosis [K]) were calculated by two experienced radiologists after postprocessing. STATISTICAL TESTS: For the differences in all the parameters between the baseline and each timepoint for both the treated and the control mice, the Mann–Whitney test was used. The Spearman correlation test was used to evaluate correlations among the DKI parameters and corresponding pathologic necrosis fraction (NF). RESULTS: ADC, D, and K values were significantly different between the two groups after treatment (P < 0.05). Serial measurements in the treated group showed that the ADC, D, and K values were significantly different at 7, 14, 21, and 28 days compared with baseline (P < 0.05). There were significant correlations between DKI parameters and NF (ADC, r = 0.865, P < 0.001; D, r = 0.802, P < 0.001; K, r = –0.944, P < 0.001). The ILXPCI results in the treated group showed a stronger absorption area than the control group. DATA CONCLUSION: DKI may be used to evaluate the complete course therapeutic effects of gastric cancer induced by TGF‐β1 inhibition, and the ILXPCI technique will improve the tumor microstructure resolution. Level of Evidence: 1 Technical Efficacy: Stage 4 J. Magn. Reson. Imaging 2019;49:1553–1564.