Intravoxel incoherent motion diffusion-weighted imaging for monitoring chemotherapeutic efficacy in gastric cancer

AIM: To assess intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) for monitoring early efficacy of chemotherapy in a human gastric cancer mouse model.METHODS: IVIM-DWI was performed with 12 b-values (0-800 s/mm2) in 25 human gastric cancer-bearing nude mice at baseline (day 0), and then they were randomly divided into control and 1-, 3-, 5- and 7-d treatment groups (n = 5 per group). The control group underwent longitudinal MRI scans at days 1, 3, 5 and 7, and the treatment groups underwent subsequent MRI scans after a specified 5-fluorouracil/calcium folinate treatment. Together with tumor volumes (TV), the apparent diffusion coefficient (ADC) and IVIM parameters [true water molecular diffusion coefficient (D), perfusion fraction (f) and pseudo-related diffusion coefficient (D*)] were measured. The differences in those parameters from baseline to each measurement (ΔTV%, ΔADC%, ΔD%, Δf% and ΔD*%) were calculated. After image acquisition, tumor necrosis, microvessel density (MVD) and cellular apoptosis were evaluated by hematoxylin-eosin (HE), CD31 and terminal-deoxynucleotidyl transferase mediated nick end labeling (TUNEL) staining respectively, to confirm the imaging findings. Mann-Whitney test and Spearman’s correlation coefficient analysis were performed.RESULTS: The observed relative volume increase (ΔTV%) in the treatment group were significantly smaller than those in the control group at day 5 (ΔTVtreatment% = 19.63% ± 3.01% and ΔTVcontrol% = 83.60% ± 14.87%, P = 0.008) and day 7 (ΔTVtreatment% = 29.07% ± 10.01% and ΔTVcontrol% = 177.06% ± 63.00%, P = 0.008). The difference in ΔTV% between the treatment and the control groups was not significant at days 1 and 3 after a short duration of treatment. Increases in ADC in the treatment group (ΔADC%treatment, median, 30.10% ± 18.32%, 36.11% ± 21.82%, 45.22% ± 24.36%) were significantly higher compared with the control group (ΔADC%control, median, 4.98% ± 3.39%, 6.26% ± 3.08%, 9.24% ± 6.33%) at days 3, 5 and 7 (P = 0.008, P = 0.016, P = 0.008, respectively). Increases in D in the treatment group (ΔD%treatment, median 17.12% ± 8.20%, 24.16% ± 16.87%, 38.54% ± 19.36%) were higher than those in the control group (ΔD%control, median -0.13% ± 4.23%, 5.89% ± 4.56%, 5.54% ± 4.44%) at days 1, 3, and 5 (P = 0.032, P = 0.008, P = 0.016, respectively). Relative changes in f were significantly lower in the treatment group compared with the control group at days 1, 3, 5 and 7 follow-up (median, -34.13% ± 16.61% vs 1.68% ± 3.40%, P = 0.016; -50.64% ± 6.82% vs 3.01% ± 6.50%, P = 0.008; -49.93% ± 6.05% vs 0.97% ± 4.38%, P = 0.008, and -46.22% ± 7.75% vs 8.14% ± 6.75%, P = 0.008, respectively). D* in the treatment group decreased significantly compared to those in the control group at all time points (median, -32.10% ± 12.22% vs 1.85% ± 5.54%, P = 0.008; -44.14% ± 14.83% vs 2.29% ± 10.38%, P = 0.008; -59.06% ± 19.10% vs 3.86% ± 5.10%, P = 0.008 and -47.20% ± 20.48% vs 7.13% ± 9.88%, P = 0.016, respectively). Furthermore, histopathologic findings showed positive correlations with ADC and D and tumor necrosis (rs = 0.720, P < 0.001; rs = 0.522, P = 0.007, respectively). The cellular apoptosis of the tumor also showed positive correlations with ADC and D (rs = 0.626, P = 0.001; rs = 0.542, P = 0.005, respectively). Perfusion-related parameters (f and D*) were positively correlated to MVD (rs = 0.618, P = 0.001; rs = 0.538, P = 0.006, respectively), and negatively correlated to cellular apoptosis of the tumor (rs = -0.550, P = 0.004; rs = -0.692, P < 0.001, respectively).CONCLUSION: IVIM-DWI is potentially useful for predicting the early efficacy of chemotherapy in a human gastric cancer mouse model.

Evaluation Value of Intravoxel Incoherent Motion Diffusion-Weighted Imaging on Early Efficacy of Magnetic Resonance-Guided High-Intensity Focused Ultrasound Ablation for Uterine Adenomyoma

To investigate the evaluation value of intravoxel incoherent motion diffusion-weighted imaging(IVIM-DWI)on the early efficacy of magnetic resonance-guided high-intensity focused ultrasound(MRgFUS)ablation for uterine adenomyoma.The clinical and magnetic resonance imaging(MRI)data of 36 patients with uterine adenomyoma before and after MRgFUS treatment in our hospital from January 2018 to December 2018 were retrospectively analyzed.All the 36 patients underwent MRI examination one day before operation and immediately after operation using GE Discovery MR7503.0T MRI,including conventional sequences(T1WI,T2WI,and T2 fat suppression sequences)plain scan,IVIM-DWI sequences with 9 b values,and contrast enhanced-MRI sequences.The IVIM-DWI quantitative parameters(true diffusion coefficient D,perfusion related diffusion coefficient D*,and perfusion fraction f)of double-exponential model were obtained by using GE ADW 4.7 functool,a postprocessor.SPSS 24.0 software was used to analyze the difference in parameter between the ablation and non-ablation areas of uterine adenomyoma.DWI signal in the ablation area of uterine adenomyoma was increased,and manifested as heterogeneous diffuse high signal,with low central signal and high edge signal.Values of D,D*and f in the ablation area of uterine adenomyoma were significantly lower than those in the non-ablation area,and there was statistical difference between the two(P<0.05).The areas under receiver operating characteristic(ROC)curve of D,D*and f values in the ablation area of uterine adenomyoma were 0.854,0.898 and 0.924,respectively;the optimal thresholds for the diagnosis of ablation area of uterine adenomyoma were 0.81×10−3 mm2/s,4.99×10−3 mm2/s and 0.24,respectively;the diagnostic sensitivity was 80.6%,72.2%and 94.4%,respectively;and the specificity was 91.7%,97.2%and 94.4%,respectively.IVIM-DWI has a certain clinical value in the evaluation on early efficacy of MRgFUS ablation of uterine adenomyosis.