摘要目的：探讨多b值磁共振扩散加权成像（ MbDWI）在局部进展期胰腺癌（ LAPC）射波刀治疗后近期疗效评估中的应用价值。方法36例LAPC患者在放疗前及放疗后1、3个月均接受胰腺MRI常规序列及MbDWI扫描（ b值分别为0、25、50、75、100、150、200、400、600、800、1000 s／mm2），采用单指数模型及双指数模型分别拟算出标准表观扩散系数（ ADC）值（ ADCtot）、灌注分数（ f）、假性扩散系数（ Dfast）及单纯扩散系数（ Dslow），观察诸参数在放疗前后的变化趋势。结果放疗前及放疗后1、3个月病灶实质区ADCtot值分别为（1．56±0．29）×10－3、（1．75±0．31）×10－3、（1．86±0．46）×10－3 mm2／s；Dslow值分别为（1．10±0．73）×10－3、（1．19±0．97）×10－3、（1．49±0．46）×10－3 mm2／s； Dfast值分别为（83．33±62．57）×10－3、（124．57±123．10）×10－3、（108．07±96．67）×10－3 mm2／s；f 值分别为（26．81±23．74）％、（23．61±22．75）％、（21．34±15．36）％。放疗后1、3个月ADCtot值显著高于放疗前，放疗后3个月Dslow值显著高于放疗前，差异均有统计学意义（P值均＜0．05），其余两两组间及放疗前后病灶实质区Dfast、f值的差异均无统计学意义。结论射波刀治疗后，ADCtot及Dslow均有明显增大的趋势，目标靶病灶实质区囊变程度变大，能够反映射波刀治疗后的近期疗效。

abstractsObjective To explore the value of Multiple b value DWI ( MbDWI ) in the short-term efficacy evaluation of cyberknife radiotherapy for locally advanced pancreatic cancer ( LAPC ) .Methods A total of 36 patients underwent both conventional sequence and respiratory triggered MbDWI ( b=0, 25, 50, 75, 100, 150, 200, 400, 600, 800, 1 000 s/mm2 ) before cyberknife radiotherapy, 1month and 3 months after the radiotherapy, respectively.ADCtot, f, Dfast and Dslow were calculated using single and double exponential model and the changes before and after radiotherapy were observed.Results Before radiotherapy, 1 month and 3 months after radiotherapy, the ADCtot values of solid lesions were (1.56 ±0.29) ×10-3 mm2/s, (1.75 ±0.31) ×10 -3 mm2/s and (18.6 ± 0.46) ×10 -3 mm2/s;the values of Dslow were (1.10 ±0.73) × 10 -3 mm2/s, ( 1.19 ±0.97 ) ×10 -3 mm2/s and ( 1.49 ±04.6 ) ×10 -3 mm2 s/; the values of Dfast were (83 .33 ±62 .57) ×10 -3 mm2/s,(124.57 ±123.10) ×10 -3 mm2/s and (108.07 ±96 .67) ×10 -3 mm2 /s; f values were (26.81 ±23.74)%,(23.61 ±22.75)% and (21.34 ±15.36)%, respectively.ADCtot values 1 month and 3 months after treatment were significantly higher than those before treatment and Dslow 3 months post-treatment was higher than that before treatment, and the differences were statistically significant ( both P<0.05) and no other differences between two groups were significant.There were no statistical differences on Dfast and f before and after radiotherapy.Conc lusions ADCtot and Dslow both showed a significant growth&nbsp;trend after cyberknife radiotherapy.The advanced degree of parenchymal cystic in the targeted lesion could reflect the short-term efficacy of cyberknife treatment.