能谱CT在精准勾画继发阻塞性不张的中央型肺癌放疗靶区中的价值

The value of Spectral CT in Precisely Delineating the Radiotherapy Targets of Central Lung Cancer with Obstructive Atelectasis

目的:探讨能谱CT在鉴别中央型肺癌与阻塞性肺不张中的价值,以实现临床放疗靶区的精确划定。方法:搜集我院经病理及CT证实、拟行放疗的89例中央型肺癌合并阻塞性肺不张患者,分析增强各期能谱CT资料。①利用能谱CT优化对比噪声比(CNR)技术得到肿瘤与不张肺组织对比度最好时的单能量CT值;②比较混合能量图像(PI)、最佳单能量图像(BMI)与最佳单能量-碘基伪彩融合图(BMI-ICM)瘤-肺交界面的主观评分与检出率;③比较肿瘤与不张肺组织的碘浓度(IC)值。结果:①增强各期肿瘤与不张肺组织均在56 keV时取得最佳CNR。②瘤-肺交界面主观评分:PI、BMI和BMI-ICM三者间有统计学差异,两两比较显示BMI-ICM最高,BMI次之,PI最低(均P<0.05);瘤-肺交界面检出率:BMI和BMI-ICM均显著高于PI(均P<0.05),但BMI与BMI-ICM间无统计学差异(P>0.05)。③增强各期肿瘤平均IC低于不张肺组织(P<0.001)。结论:能谱CT有助于鉴别中央型肺癌与阻塞性肺不张,为临床放疗靶区的精准勾画提供了新的方法。

Purpose:To investigate the value of spectral CT in distinguishing central lung cancer from obstructive atelectasis for achieving the accurate delineation of clinical radiotherapy targets.Methods:A total of 89 patients with central lung cancer and obstructive atelectasis confirmed by pathology and CT results in our hospital were collcted and analyzed as follows:①The technology of optimized contrast noise ratio(CNR)of spectral CT was used to get the monochromatic CT value when tumors and atelectasis showed the best contrast;②The subjective scores and detection rates of tumor-lung interface between the polychromatic image(PI),the best monochromatic image(BMI)and the best monochromatic image combined with iodine concentration map(BMI-ICM)were compared;③The iodine concentration(IC)between tumors and atelectasis was compared.Results:①The monochromatic CT value when tumors and atelectasis showed the best contrast was 56 keV.②Statistical differences in the subjective scores of tumor-lung interface were observed between PI,BMI and BMI-ICM;The pairwise comparison showed that the subjective score of BMI-ICM was the highest,while that of BMI was the second and PI was the lowest(all P<0.05).Meanwhile,the detection rates of tumor-lung interface of BMI and BMI-ICM were significantly higher than that of PI(all P<0.05),but there was no statistical difference between BMI and BMI-ICM(P>0.05).③The average IC of tumors was lower than that of atelectasis in each phase(P<0.001).Conclusion:Spectral CT is helpful to distinguish central lung cancer from atelectasis and provides a new method to delineate the clinical radiotherapy targets accurately.