Application of CT perfusion imaging in radiotherapy for lung cancer

Objective To investigate the value of CT perfusion imaging in evaluation of therapeutic effect and prognosis in radiotherapy for lung cancer.Methods Fifty-one cases of lung cancer who were unable or refused to be operated on,36 males and 15 females,aged 37 - 80,underwent CT perfusion imaging,29 of which only before radiotherapy and 22 before and after radiotherapy twice.The images were collected by cine dynamic scanning (5 mm/4 slices ) and input into the GE AW4.0workstation for data processing.The slice positions of CT imaging were determined according to the largest tumor size in CT scan.Regions of interest of tumor were drawn at the region corresponding to the original images of CT perfusion.Radiotherapy was performed after CT perfusion imaging.Relevant parameters,including blood flow ( BF),blood volume ( BV),mean transit time ( MTT),and permeability surface (PS) were calculated.The treatment response after radiotherapy was evaluated by RECIST.At 2 -4 weeks after the treatment,CT examination was conducted once more.Results The tests of the 51 patients showed that the BV was 13.6 ml·100 g-1,the BF was 129.5 ml·min-1 ·100 g-1,the MTT was 9.1 s,and the PS was 10.0 ml· min- 1· 100 g-1 before radiotherapy.The tests of the 22 of the 51 patients showed that the values of BV and BF after radiotherapy were 7.6 ml· 100 g-1 and 97.8 ml·min-1· 100 g-1,respectively,both lower than those before radiotherapy (11.2 and 108.7 ml·min-1·100g-1,respectively),however,both not significantly ( t =1.28,0.40,P ＞ 0.05 ) ; and the values of MTT and PS after radiotherapy were 8.9 s and 7.8 ml·min-1· 100 g-1,respectively,both not significantly higher than those before radiotherapy ( 7.2 s and 6.8 ml· min -1· 100 g-1,respectively,t =- 1.15,- 0.57,P ＞0.05 ).The mean area of tumor after radiotherapy was 1189.6 mm2,significantly less than that before radiotherapy ( 1920.3 mm2,t =3.98,P ＜0.05).The MTT of the SCLC patients was 12.9 s,significantly longer than that of the NSCLC patients (6.5 s,t =2.54,P ＜0.05).The MTT of the tumor with the area ≤ 10 cm2 was 11.2 s,significantly longer than that of the tumors with an area ＞ 10 cm2(5.8 s,t =2.59,P ＜ 0.05 ).The BV of the responder group was 19.2 ml· 100 g- 1,significantly higher than that of the nonresponder group (4.6 ml· 100 g - 1,t =3.62,P ＜ 0.05 ).There were not significant differences in all the perfusion characteristics between the cases with the disease-free advanced survival time ≤ 10 months and those with disease-free advanced survival time ＞ 10 months.Conclusions CT perfusion imaging helps in diagnosis and radiotherapy of lung cancer to a certain degree. Key words: Computed tomography;  Perfusion imaging;  Lung cancer;  Radiotherapy