两种高b值的DWI成像在直肠癌的应用价值比较

目的比较两种高b值磁共振弥散加权成像(diffusion weighted imaging,DWI)在直肠病变诊断中的应用价值。方法使用3.0T MRI对直肠癌进行常规直肠扫描及DWI扫描,DWl采用平面回波(echo planar imaging,EPI)序列,选用2个不同的b值(1000s/mm~2、2500s/mm~2),测量肿瘤及同侧臀大肌在不同b值下DWI图像上表观弥散系数(apparent diffusion coefficient,ADC),并进行比较分析。结果 b值等于1000s/mm~2时,肿瘤的ADC值为(0.923±0.15)×10-3mm~2/s,而臀大肌的ADC值为1.57±0.091×10~(-3)mm~2/s,b值等于2500s/mm~2时,肿瘤的ADC值为(0.642±0.07)×10~(-3)mm~2/s,而臀大肌的ADC值为(0.925±0.12)×10~(-3)mm~2/s。所得肿瘤与臀大肌的ADC比值两组间存在差异。结论 b值等于1000s/mm~2组的DWI图像的ADC比值高于2500s/mm2组,更加有利于显示病变,ADC值可作为直肠癌诊断及评价预后的指标之一。

The Comparison of Application Value Between the Two Different b Value of DWI in Rectal Cancer

Objective To compare the appicaiton value btween the two different high b value of diffusion weighted imaging (DWI) in colorectal carcinoma. Methods All patients with rectal carcinoma underwent conventional scanning and DWI scanning by 3.0T MRI. In DWI, two different b value (1000 and 2500s/mm2)were used. The ADC value of tumor and ipsilateral gluteus maximus under different b value on DWI were measured and compared. Results When b value is 1000s/mm2, ADC value in tumor was (0.923±0.15)×10-3mm2/s, and in glutes were (1.57±0.091)×10-3mm2, when b value is 2500s/mm2, ADC value in tumor was (0.642±0.07)×10-3mm2/s, and in glutes were (0.925±0.12)×10-3mm2/s. There was significant difference in ADC ratio of tumor and glutes between the two groups. Conclusion The value of ADC ratio in the group which b value is 1000 s/mm2 was higher than that whose b value is 2500s/mm2, ADC value can be used as a index of diagnosis and prognosis evaluation for rectal cancer.