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

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-α 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 RILI occurred in 18 of 48 cases ( 18/48,Group A).In Group A,TNF-α and TGF-β1 preand pos-radiation were (36.1 ± 15.0),(30.4 ±t 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.I0,P =0.264,0.279).At half-dose time point of radiation,there were no significant differences for TNF-α and TGF-β1 pre- and posradiation [ ( 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 RILI 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. Key words: Tomography, spriral computed;  Radiotherapy;  Radiation pneumonitis;  Early diagnosis;  Perfusion imaging