食管肿瘤扩散加权成像序列参数优化及相关影像病理对照研究

目的探讨食管肿瘤磁共振扩散成像的技术可行性和b值的选择,比较扩散成像与食管钡餐造影、CT、T2WI在显示病变长度方面的差异.方法食管肿瘤32例,进行常规MRI及DWI横断面扫描b=200、300、500、800、1000s/mm2,分别测定图像SIR和CNR并与常规T2WI图像进行比较.测量食管肿瘤病变的扩散信号强度,分别计算ADC值,选择合适的b值.在DWI图像上测量病变长度,与食管钡餐造影、CT、T2WI及手术切除病理大体标本显示的病变长度进行比较.结果不同b值DWI图像与常规T2WI比较,SIR无显著性差异(P＞0.05),b值为200、300、500 s/mm2时,DWI图像CNR与T2WI有显著性差异(P＜0.05).b值200、300、500 s/mm2DWI图像的SIR和CNR与b值选择800、1000s/mm2时有显著性差异(P＜0.05),b值选择500 s/mm2较为合适.b值500 s/mm2磁共振扩散加权图像显示病变长度与病理结果、食管钡餐造影及T2WI图像无显著性差异(P＞0.05).结论应用8通道阵列线圈结合ASSET技术一次屏气扫描,b值采用500 s/mm2可以获得较为满意的食管肿瘤扩散图像,DWI测量的病变长度与手术切除病理大体标本无显著性差异;DWI与钡餐造影和MRI T2WI在显示病变长度方面有较好的对应关系.

The optimization of diffusion-weighted imaging parameters in esophageal cancer and comparison with X-ray double-contrast imaging, CT, MR T2WI and pathology

Objective To evaluate the technical feasibility of diffusion-weighted MR imaging (DWI) of esophageal tumor and the choice of b value and compare the difference among DWI, X-ray double-contrast imaging, CT and MR T2WI in displaying of the lesion extent. Methods Thirty-two patients with esophageal cancer were examined at 1.5T MR scanner. The conventional and DW-MRI were both imaged at axial plane. The b values were 200, 300, 500, 800, 1000 s/mm2. Signal-intensity ratio (SIR) and contrast-to-noise ratio (CNR) were calculated and compared between DWI and T2WI. Apparent diffusion coefficients (ADCs) were calculated and the appropriated b value was determined. The extent of the lesion was measured on DWI, X-ray double-contrast imaging, CT, MR T2WI, and pathology results. Results The SIRs had no statistical difference between T2WI and DWI with different b values (P>0.05), but the CNRs had statistical difference between T2WI and DWI with b values of 200, 300 and 500 s/mm2 (P>0.05). There was statistical difference between DWI with b values of 200, 300, 500 s/mm2 and those with 800 and 1000 s/mm2 (P>0.05), b=500 s/mm2 was a preferred choice. There was no statistical difference in the defining of lesion extent between DWI (b=500 s/mm2) and pathology result, X-ray double-contrast imaging, and T2WI (P>0.05). Conclusion Satisfied diffusion weighted images can be achieved through the combination of 8-channel phase array coil and ASSET techniques with a b value of 500 s/mm2. The extent of lesions on DWI has no difference with pathology results.