Pulmonary Perfusion Imaging With 64-Slice Spiral CT In Radiation-Induced Lung Injury (RILI): Primary Clinical Study

This study was divided into two parts:Part One,to evaluate the feasibility of scan techniques in 64-slice CT pulmonary perfusion,as well as the reliability of perfusion parameters measured and obtained;Part Two,To study the regional pulmonary hemodynamic changes of radiation lung injury(RILI)or radiation pneumopathy(RP)via the measurement of CT perfusion(CTP)parameters.Part One:Technology of pulmonary perfusion imaging with 64-slice CT scannerObjective To evaluate the feasibility of scanning techniques and the reliability of perfusion parameters via volunteers in 64-slice CT pulmonary perfusion.Materials and methods Lung scan of eight adult volunteers(4 males and 4 females)was performed with the body perfusion technique of 64-slice CT scanner.The method of deep-inspiration breathhold was used during scanning.The scanning time lasted 30 s;the scanning scope included the pulmonary hilum;injection rate was set at 6.0 mL/s via high pressure syringer.All raw data were postprocessed via Syngo workstation in order to produce the perfuion images.Normal lung field was divided into two parts(right and left) and three parts(anterior,middle and posterior).The perfusion parameters in the above parts,such as BF(blood flow),BV(blood volume)and PS(permeability surface),were measured using the same size of region of interest(ROI).The results were compared so as to find the difference between genders or locations(right vs left;every two parts among anterior,middle and posterior).Results(1)In all subjects,the satisfactory CTP images were produced with nice layers and structures.Stable data could be gained from each different size of ROIs in lung field;(2) The normal pulmonary BF,BV and PS were 146.1±35.4 mL/100mL/min,13.53±2.96 mL/100mL,9.41±2.87 mL/100mL/min,respectively;(3)there was no significant difference between the genders for all the above parameters obtained(P＞0.05);there was significant difference,for BF and BV,between the anterior and posterior lung fields (P＜0.05)and no significant difference for all perfusion parmeters,between anterior and middle or middle and posterior fields(P＞0.05).Conclusion(1)Pulmonary perfusion can be performed successfully using 64-slice CT scanner,with which quantitative analysis and pulmanry hemodynamic parameters(rBF, rBV,rPS)can be achieved.(2)Except for the significant difference between the anterior and posterior lung fields as to BF and BV,(P＜0.05),there were no significant difference for other perfusion parameters,between each two parts of lung field(P＞0.05).Part Two:Study of the regional pulmonary hemodynamic changes of RILl with CTP.Objective To study the value and capability of diagnosing and predicting the acute RILI with CTP technique in non-lung cancer patients with thoracic tumor radiation therapy (RT).Materials and Methods 51 cases of non-lung cancer patients with thoracic tumors were divided into two groups(A and B).All patients received postoperative or pure irradiation of 60～66Gy dose of total(DT).Group A and B underwent 64-Slice CTP at the different postirradiation time points(0w,4w,12w,24w and 4w,8w,16w,32w,repectively).Results(1)18 cases of acute RILI occurred among all patients(Grade 1 to Grade 4:4,5,7, 2,respectively).The curves of rBF and rBV showed slow-rising till 8w,then slow-dropping;rPS curve rapid-rising till 4w,then slow-dropping.(2)At the time point of 4w(i.e.half dose of total,1/2 DT,RILI didn't occur if only rrBF or/and rrBV elevated; otherwise,Grade 1-4 of RILI occurred if rrBF,rrBV and rrPS elevated together.(3)Higher relative perfusion values and abnormal HRCT signs were considered as the main distinction for Grade 1-2 RILI,which was different from Grade 3-4.(4)At 1/2 DT,the predicting capability of rrBF for acute RILI was close to rrBV(sensitivity,73.5%,70.9%; specificity,76.5%,70.7%,respectively).Sensitivity and specificity of rrPS achieved to 85.3%and 75.4%.But the predicting capability for combination of the above was strikingly higher(sensitivity,91.2%;specificity,80.2%).Conclusion(1)Values of CTP parameters may reflect the hemodynamic changes of postirradiation lung.(2)CTP can detect acute RILI which showed negative in HRCT.CTP has sinificant higher sensitivity and specificity in diagnosing Grade 1-2 of RILI.(3)CTP can be used to predict acute RILI and rrBF,rrBV and rrPS were the key parameters.In addition,rrPS plays more important role for predicting in acute stage of RILI and it also has potential value in predicting RF.(4)Standardized perfusion parameters are recommended for diagnosing or predicting different grades of RILI,and their combination is superior to single parameter for predicting.