64层CT灌注成像早期诊断放射性肺损伤的临床价值

64-slice CT perfusion imaging for the early diagnosis of radiation-induced lung injury

目的 探讨64层CT灌注成像（CTPI）早期诊断放射性肺损伤（RILI）的临床价值。方法48例接受术后放疗的上段食管癌患者（照射总剂量均为60Gy），放疗前及放疗1／2总剂量时间点（30Gy）行CTPI检查，同期检测外周血中肿瘤坏死因子（TNF-a）、转化生长因子（TGF-β），分析发生RILI（A组）与未发生RILI（B组）患者的血清细胞因子、常规CT表现及CTPI灌注值[相对血流量（rrBF）、相对血容量（rrBV）、相对毛细血管通透性（rrPS）]的变化，采用随机区组设计t检验比较两组间血清细胞因子、CTPI灌注值的差异，采用x2检验比较常规cT与CTPI对RILI检出的差异。结果48例患者中，18例发生RILI（A组）。A组放疗前外周血TNF-a和TGF．B1分别为（36．1±15．0）ng／L、（17．54-9．8）μg/L，放疗后分别为（30．4±14．9）．g／L、（14．3±7．6）μg／L，放疗前后的差异无统计学意义（t值分别为1．14、1．10，P值分别为0．264、0．279）。放疗1／2总剂量时，A、B两组的外周血TNF—a分别为（30．4±14．9）、（28．9±14．7）．g／L，TCF—B，分别为（14．3±7．6）、（14．4±6．0）μg/L，两组间差异无统计学意义（t值分别为0．33、1．23，P值分别为0．746、0．227）；但A组常规CT图像上有2例出现阳性征象。受照射肺组织rrBF、rrBV、rrPS照射前，A组分别为1．01±0．13、1．01±0．07、1．03±0．15，B组分别为1．01±0．09、1．00±0．12、1．01±0．17；照射后，A组分别为1．32±0．19、1．30±0．20、1．38±0．20，B组分别为1．20±0．14、1．21±0．09、1．06±0．16。A组受照射肺组织rrBF、rrBV、rrPS均较照射前显著增高，差异有统计学意义（t值分别为5．67、5．97、6．11，P值均为0．000）；B组的rrBF、rrBV较照射前有增高，差异有统计学意义（t值分别为6．52、7．84，P值均为0．000），rrPS无明显变化，差异无统计学意义（t=1．36，P=0．178）；照射后A、B两组rrBF、rrBV、rrPS间差异均有统计学意义（t值分别为2．32、2．18、6．04，P值分别为0．025、0．034、0．000）。根据ROC曲线，设rrPS=1．28为阈值，诊断RILI的敏感度、特异度分别为77．8％、93．3％，高于常规CT的11．1％、90．0％，两者差异有统计学意义（x2=13．61，P=0．000）。结论外周血中TNF-a、TGF—β1变化对早期检测肿瘤放疗患者RILI的价值尚不确定。CTPI可反映放疗后肺组织血液动力学的变化，可早期反映RILI患者照射野的灌注异常，有可能早期检出RILI。

Objective To explore the value of 64-slice CT perfusion imaging（CTPI） in the early diagnosis of radiation-induced lung injury （RILI）. Methods Forty-eight patients with upper esophageal cancer resection underwent CTPI before and after radiotherapy, and the TNF-a and TGF-β1 were measured from patient＇s peripheral blood. Serum cytokine, conventional CT appearances and CTPI parameters （rrBF, rrBV, rrPS） in patients with RILI（ Group A） and non-RILI （Group B） were compared and analyzed. A randomized block design t-test was used for comparison of serum cytokines and perfusion values between the two groups. The Chi-square （ X2 ） test was used for comparison of detection rate between conventional CT and CTPI. Results RILl occurred in 18 of 48 cases （18/48, Group A）. In Group A, TNF-a and TGF-β1 pre- and pos-radiation were （36.1±15.0）,（30.4 ±14.9） ng/L and （17.5 ±9.8）, （14.3 ±7.6）μg/L, respectively, and there were no statistically significant differences （t = 1.14, 1.10, P =0. 264, 0. 279）. At half-dose time point of radiation, there were no significant differences for TNF-a and TGF-β pre- and pos- radiation [（30.4±14.9）,（28.9±14.7） ng/L and （14.3±7.6）, （14.4±6.0） μg/L, respectively] between Group A and B （ t = 0. 33, 1.23 ; P = 0. 746, 0. 227）. The rrBF, rrBV and rrPS of post-radiation from Group A were significantly higher than those of pre-radiation （ t = 5.67,5.97, 6. 11, P = 0. 000, 0. 000,0. 000） , the rrBF and rrBV of post-irradiation from Group B were significantly higher than those of pre-irradiation （t =6. 52, 7. 84, P =0. 000, 0. 000）. There was no significant difference for rrPS in Group B pre- and post-radiation （t = 1.36,P =0. 178）. There were significant differences for all perfusion values detected from radiation lung fields between Group A and B （t = 2. 32, 2. 18, 6. 04, P = 0. 025, 0. 034, 0. 000）. Taking rrPS = 1.28 as a threshold value on ROC, the sensitivity and specificity of CTPI for diagnosis of RILl were 77. 8% , 93.3% , respectively, which were much higher than those （ 11.1% , 90. 0%, respectively） of conventional CT （X2 = 13.61, P = 0. 000） . Conclusion CTPI parameters may reflect the hemodynamic changes of post-radiation lung and have potential values for the early diagnosis of RILI.