信噪比在肾透明细胞癌多b值DWI分析中的重要性研究
Evaluation of signal noise ratio on analysis of clear cell renal cell carcinoma using DWI with multi-b values
目的 探讨信噪比对肾透明细胞癌多b值DWI信号强度变化趋势可能的影响.方法 回顾性分析2011年7月至2012年4月在常州市第一人民医院放射科17例透明细胞癌患者的影像学资料,其中17个肿瘤病灶,9个单纯性囊肿纳入统计.分别测量囊肿及肿瘤的各b值DWI信号强度.寻找适合囊肿呈单指数函数变化的最低信噪比(即,阈值);计算透明细胞癌各b值DWI的信噪比,并采用两独立样本t检验将其与阈值比较.结果 肾囊肿及透明细胞癌的DWI信号强度均随着b值的增大而减小.囊肿的多b值DWI信号强度变化呈单指数函数的最小信噪比(阈值)为(1.29±0.17)(b =800 s/mm2).在肾脏透明细胞癌各b值DWI中,当b=1 000 s/mm2时,其信噪比与阈值差异无统计学意义(t =0.40,P=0.69);当b=1 200时,信噪比低于阈值(£=-2.38,P=0.03).结论 信噪比足够高是DWI定量分析的前提条件,适合肾透明细胞癌DWI分析的最大b值为1 000 s/mm2.
更多Objective To explore the influence of signal noise ratio (SNR) on analysis of clear cell renal cell carcinoma (CCRCC) using DWI with multi-b values.Methods The images of 17 cases with CCRCC were analyzed,including 17 masses and 9 pure cysts.The signal intensity of the cysts and masses was measured separately on DWI for each b value.The minimal SNR,as the threshold,was recorded when the signal curve manifest as the single exponential line.The SNR of the CCRCC was calculated on DWI for each b value,and compared with the threshold by independent Two-sample t Test.Results The signal decreased on DWI with increased b factors for both pure cysts and CCRCC.The threshold is 1.29 ± 0.17,and the signal intensity of the cysts on DWI with multi-b values shown as a single exponential line when b ≤ 800 s/mm2.For the CCRCC,the SNR is similar to the threshold when b =1 000 s/mm2 (t =0.40,P =0.69),and is lower when b=1 200 s/mm2(t =-2.38,P=0.03).Conclusion The SNR should be sufficient for quantitative analysis of DWI,and the maximal b value is 1000 s/mm2 for CCRCC.
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