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Background：Intravoxel incoherent motion imaging (IVIM) and DWI have been applied for gastric adenocarcinoma.Purpose: To investigate correlation between parameters of IVIM and DWI with Ki-67 in gastric adenocarcinoma.Materials and methods: A total of 64 gastric adenocarcinoma patients were enrolled into the research and received DWI and IVIM at 3.0T MRI before the surgery. Based on the setting of ROIs, the DWI and IVIM parameters (including ADC, ture diffusion coefficient (D), perfusion fraction (f) and pseudo-diffusion coefficient (D*)) of each patient's gastric adenocarcinoma were measured and calculated. According to expression of Ki-67, participated subjects were divided into two groups (low Ki-67 group and high Ki-67 group). The intraclass correlation coeffificient (ICC) was used to assess the consistency of each parameter measured by two radiologists. The independent-sample t-test was used to compare differences of each parameter between groups. Spearman correlation coefficient was calculated to reveal the correlation between Ki-67 with parameters. By using the area under the curve (AUC) of the receiver operating characteristic (ROC) curve, each parameter was compared. Results: The ADC, D and f values of high Ki-67 group were all lower than those of low Ki-67 group [(10.89±0.89) × 10−2 mm2/s vs. (14.65±0.46)× 10−2 mm2/s, (9.95±0.92) × 10−2 mm2/s vs. (12.48±0.83) × 10−2 mm2/s, (2.30±0.51) × 10−2 mm2/s vs. (3.75±0.85) × 10−2 mm2/s, all P < 0.05]. Except for D*, ADC, D and f were negatively correlated with the expression of Ki-67 (r = −0.725, −0.733, -0.666, all P < 0.05). The areas under the curve (AUC) of ADC, D and f were 0.901, 0.923 and 0.657 respectively (Table 5). The difference of AUC value between ADC and D was not statistically significant (AUCD = 0.923 vs. AUCADC= 0.901, Z=0.290, P=0.772). The difference of AUC value between ADC and f was statistically significant (AUCADC= 0.901 vs. AUCf= 0.657, Z=2.329, P=0.025). The difference of AUC value between D and f was statistically significant (AUCD= 0.923 vs. AUCf= 0.657, Z=2.124, P=0.034) (Table 6).Conclusions: DWI and IVIM can effectively reflect the proliferative characteristics of gastric adenocarcinoma. D and ADC have higher diagnostic efficiency than f.

Background: Reduced field-of-view diffusion-weighted imaging (rFOV-DWI) could be proved to quantitatively identify papillary thyroid carcinoma (PTC) and there is no literature regarding the use of T1 mapping to distinguish nodular goiter (NG) from PTC.