Evaluation And Prediction Of Radiotherapy Response Using MSCT Perfusion In Patients With Advanced Lung Cancer

Purpose:To discuss the clinical application of MSCT perfusion imaging for evaluating and predicting radiotherapy effect in patients with advanced lung cancer and seek the best perfusion indicator.Method and material:19 continuous patients with unresectable advanced lung cancer in our hospital,without other therapy and with complete clinical data and clear pathologic diagnosis,were enrolled. 19 continuous patients had completed CT perfusion imaging within 1week before first radiotherapy and at 4 weeks after first radiotherapy and performed first therapeutic evaluation. Moreover, 13 patients again had completed CT perfusion imaging at 2-4 months after first radiotherapy and performed second therapeutic evaluation. Patients of loss of follow up were 6 cases. Therapeutic evaluation of lung carcinoma was performed according to RECIST1.1 criterion.Parameters were measured at maximum slice. The evaluating indicators including:(1) Measuring the longest diameter of lung cancer and its vertical diameter in the maximum slice of axial images and calculating its area(A).(2) Measuring the average perfusion values(BV, BF, MTT, PS).(3) Calculating the total perfusion values(BV total,BF total, MTT total, PS total) at maximum slice.(4) Calculating perfusion percent change(△BV, △BF, △MTT, △PS, △BV total, △BF total, △MTT total, △PS total) during first therapeutic evaluation. The above data was measured twice by the same person at different time(greater than 1 month).Using SPSS17.0 software, intraobserver correlation of CT perfusion parametersbetween twice measurements was performed using spearman rank correlation. To compare parameter values of MSCT perfusion(BV, BF, MTT, PS, BV total, BF total,MTT total, PS total) before and after radiotherapy using Wilcoxon test. The difference of perfusion value(BV, BF, MTT, PS, BV total, BF total, MTT total, PS total) and perfusion percent change(△BV, △BF, △MTT, △PS, △BV total, △BF total, △MTT total, △PS total)between PR group and SD group at first evaluation was evaluated by Manne-Whitney test. The difference of perfusion value(BV, BF, MTT, PS, BV total, BF total, MTT total, PS total)and perfusion percent change(△BV, △BF, △MTT, △PS, △BV total, △BF total,△MTT total, △PS total) between effective group and ineffective group was evaluated by Manne-Whitney test. The diagnostic sensitivity and specificity was evaluated using ROC curve.Results:(1) In RECIST1 measurement at 4 weeks after first radiotherapy, 19 patients with advanced lung cancer were effective(SD1 group 15 patients, PR1 group 4 patients). In RECIST2 measurement at 2-4 months after first radiotherapy, 13 patients(11 patients from SD1 group, 2 patients from PR1 group) were evaluated, and patients of loss of follow up were 6 cases(loss rate 31.57%)(4 patients from SD1 group, 2 patients from PR1 group). In RECIST2 measurement, 11 patients from SD1 group included effective group 8 cases(SD2 1 case, PR2 7 cases) and ineffective group(PD2) 3 patients.(2)Interobserver correlation of MSCT perfusion analysis was performed. B efore radiotherapy and after radiotherapy, BV, BF, MTT and PS values between twice measurements had better intraobserver correlation(All P=0.00).(3)There wasn’t significant difference for average perfusion values(BV, BF, MTT and PS) between before radiotherapy and after radiotherapy(P>0.05). However, BV total,BF total and MTT total at 4 weeks after first radiotherapy were significant lower than before radiotherapy(P=0.00, P=0.01, P=0.01). PS total also showed a declining trend(median PS total治疗前= 18.86(103), median PS total治疗后(103) = 9.72, P = 0.08)(4)Using MSCT perfusion parameters before radiotherapy as a predictor for the RECIST1 and RECIST2. In RECIST1 at 4 weeks after first radiotherapy, BV, BF, MTT,PS, BV total, BF total, MTT total and PS total had no statistical difference between PR and SD group(P>0.05). In RECIST2 at 2-4 months after first radiotherapy, the results were same between effective and ineffective group(P>0.05).(5)Using perfusion percent change as a predictor for the RECIST1. In RECIST1 at 4weeks after first radiotherapy, △BV, △BF, △MTT and △PS had no statistical difference between PR and SD group(P>0.05). But, △BV total and △PS total in PR1group(median:-0.75,-0.81) were lower than in SD1 group(median:-0.28,-0.18)(P=0.05, P=0.00.) △MTT tota between PR and SD group also showed a statistical trend(P=0.08).(6)Using perfusion percent change as a predictor for the RECIST2. △MTT had statistically difference between effective and ineffective group(P=0.01). △BV,△BF and △PS had no statistical difference between effective and ineffective group(P=0.37, P=0.69, P=0.37). At the same time, △BV total and △MTT total in effective group(median:-0.51,-0.36) was lower than in ineffective group(median: 0.29, 0.19)(P=0.01,P=0.01). The area under the curve about perfusion percent change showed AUC of△BV total and △MTT total were 0.97 and 1.00.(7)For 11 patients from SD1 group, △MTT had statistically difference between effective and ineffective group(P=0.02). △BV, △BF and △PS had no statistical difference between effective and ineffective group(P>0.05). However, △BV total,△BF total and △MTT total in effective group(median:-0.51,-0.42,-0.32) was lower than in ineffective group(median: 0.29,-0.03, 0.19)(P=0.02, P=0.05, P=0.01).Conclusion:(1)To clearly verify the practical value of MSCT perfusion on evaluating radiotherapy effect of advanced lung cancer. MSCT Perfusion could be used to evaluate and predict radiotherapy effect before morphological changes. The total perfusion percent change(△BV total, △MTT total) could be a better indicator to quantitatively evaluate and predict radiotherapy effect of advanced lung cancer.(2)For these lesions, which could be SD in early morphological evaluation of curative effect, they could show a variety of changes in future prognosis. The total perfusion percent change(△BV total, △ BF total, △MTT total) could be a better indicator to early evaluate and predict radiotherapy effect.