中文摘要：

瞄准：为了探索散开坡度 b 因素，那为估计肿瘤反应到 transarterial chemoembolization 优化两明显的散开系数(模数转换器) 大小和 contrast-to-noise (CNR )( 不作声) 在一个兔子模型。方法：在肝的 12 只新西兰白兔子适用 VX2 肿瘤被治疗与不作声。有各种各样的 b 价值的散开加权的成像(DWI ) 用一样被执行协议在前和 3 d 术后疗法与不作声。模数转换器价值和每个肿瘤预告的处理的 CNR 并且与不同 b 因素处理以后被分析。在模数转换器价值和在组织学的标本的坏死的程度之间的关联被皮尔森的关联测试分析。结果：当 b 价值增加了，散开加权的图象的质量减少了。在吝啬的 lesion-to-liver CNR 的实质的减少在预告的处理和处理以后的 DW 图象上被观察，在 CNR 预告的处理的最大的差别并且处理以后在 1000 s/mm2 的 b 值被表明(P = 0.036 ) 。散开上的治疗的效果早术后疗法被模数转换器的重要增加显示出(P = 0.007 ) ，特别与大 b 因素(】= 600 s/mm2 ) 。在肿瘤以内在场的坏死的房间的吝啬的百分比是 76.3%-97.5% 。重要积极关联与所有 b 在模数转换器价值和坏死的程度之间被发现的 A 除了 b200 珍视，在模数转换器价值和坏死的百分比之间的一个更高相对的系数与 b1000 和 b2000 在 DWI 上被发现(P = 0.002 和 0.006，分别地) 。结论：多达 600 s/mm2 的增加的 b 价值将增加模数转换器对比 pre-treatment, 并且处理以后，但是减少图象质量。考虑 CNR 和模数转换器测量，与 1000 s/mm2 的 b 价值获得的散开加权的成像为监视早肝的肿瘤反应不作声被推荐。

英文摘要：

AIM： To explore the diffusion gradient b-factor that optimizes both apparent diffusion coefficient （ADC） measurement and contrast-to-noise （CNR） for assessing tumor response to transarterial chemoembolization （TACE） in a rabbit model. METHODS： Twelve New Zealand white rabbits bearing VX2 tumors in the liver were treated with TACE. Diffusion-weighted imaging （DWI） with various b values was performed using the same protocol before and 3 d after treatment with TACE. ADC values and CNR of each tumor pre- and post-treatment with different b factors were analyzed. Correlation between ADC values and extent of necrosis in histological specimens was analyzed by a Pearson＇s correlation test.RESULTS： The quality of diffusion-weighted images diminished as the b value increased. A substantial decrease in the mean lesion-to-liver CNR was observed on both pre- and post-treatment DW images, the largest difference in CNR pre- and post-treatment was manifested at a b value of 1000 s/mm^2 （P = 0.036 ）. The effect of therapy on diffusion early after treatment was shown by a significant increase in ADCs （P = 0.007）, especially with large b factors （≥ 600 s/mm^2）. The mean percentage of necrotic cells present within the tumor was 76.3%-97.5%. A significant positive correlation was found between ADC values and the extent of necrosis with all b values except for b200, a higher relative coefficient between ADC values and percentage of necrosis was found on DWI with bl000 and b2000 （P = 0.002 and 0.006, respectively）. CONCLUSION： An increasing b value of up to 600 s/mm^2 would increase ADC contrast pre- and post-treatment, but decrease image quality. Taking into account both CNR and ADC measurement, diffusion-weighted imaging obtained with a b value of 1000 s/mm^2 is recommended for monitoring early hepatic tumor response to TACE.