| 孙应实,张晓鹏,唐磊.直肠癌扩散加权成像b值选取及其对直肠癌显示能力的评价[J].中国医学影像技术,2005,21(12):1839~1843 |
| 直肠癌扩散加权成像b值选取及其对直肠癌显示能力的评价 |
| Diffusion-weighted MR imaging of rectal cancer: determination of b values and evaluation of displaying ability |
| 投稿时间：2005-09-06 修订日期：2005-11-25 |
| DOI： |
| 中文关键词: 磁共振成像 直肠肿瘤 扩散加权成像 b值 |
| 英文关键词:Magnetic resonance imaging Rectal neoplasms Diffusion-weighted imaging b value |
| 基金项目: |
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| 中文摘要: |
| 目的 探讨扩散成像对直肠癌的显示能力和b值选取方法,确定直肠癌扩散成像的较佳b值。方法 对32例原发性直肠癌患者术前应用1.5T磁共振行MRI常规和多b值扩散成像。计算肿瘤区域组织、正常肠壁、膀胱和背景噪声的信号强度值,计算不同图像中ADC值、信噪比及对比噪声比等数据,并进行统计学分析。结果 扩散图像中肿瘤与正常肠壁的对比噪声比(CNR)随着b值的增加而下降,b值300、500、1000 s/mm2图像CNR高于T2图像和b值1300 s/mm2图像,有统计学意义(F＝42.492,P＜0.05)。扩散图像中膀胱SIR值均低于高分辨T2图像中膀胱SIR值,有统计学意义(F＝144.786,P＜0.05),b值升至800 s/mm2时,SIR降低至2.437±0.844。随着b值的增高,肿瘤ADC值逐渐变小,有统计学意义(F＝141.425, P＜0.01)。结论 b＝1000 s/mm2是直肠癌扩散成像的较佳b值,可以较好的克服灌注、T2穿透效应对直肠癌扩散成像的影响,准确反映组织的扩散特性。 |
| 英文摘要: |
| Objective To investigate the ability of diffusion-weighted imaging (DWI) in displaying rectal cancer and determine reasonable b values of DWI of rectal cancer. Methods Thirty-two patients with rectal cancer with single-shot echo planar imaging (EPI) diffusion-weighted sequences (b=300, 500, 800, 1000 and 1300 s/mm2) at 1.5T MR scanner with an 8-channel body phase-array coil. The imaging parameters were: TE/TR minimum/6000 ms, FOV 36 cm, Matrix 128×128, Slice thickness 5 mm, Nex 8. ASSET technology was used to reduce the distortion of EPI. The mean apparent diffusion coefficient (ADC) values and signal-to-noise ratio (SNR) of tumors, contrast-to-noise ratio (CNR) of tumors and normal rectal wall, signal intensity ratio (SIR) of bladder were calculated and compared. Results The CNR of tumors and normal rectal wall decreases following the descending of b values, and the CNR in the DWI with b=300, 500, 1000 s/mm2 was significantly higher than that in DWI with b=1300 s/mm2 and T2-weighted imaging (F＝42.492, P＜0.05). The SIR of bladder in DWI (b=300, 500, 800, 1000 and 1300 s/mm2) were lower than that in T2-weighted imaging (F＝144.786, P＜0.05), when b values reached 800 s/mm2 the SIR declined to 2.437±0.844. The mean ADC values of tumor were decreases following the ascending of b values. Conclusion b＝1000 s/mm2 is reasonable for DWI of rectal cancer, and that can get rid of the influence produced by blood perfusion and T2 shine through. |
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