| The purpose of this research was to measure the metabolite value and the index value in patients with brain metastases before and after radiotherapy by using MRS and DTI,analyze the value and the ratio of the tumor tissue to the contralateral normal brain tissue and the relationship between the values,screen the value that could be used for early prediction of efficacy.Methods and materialsThirty-three patients(20 male,13 female,age range from 46 to 78 years old, average 62.7 years old) with brain metastasis from pathologic confirmed lung cancer were treated by LINAC radiosurgery in combination with WBRT.21 cases were included in this group,but 12 cases were excluded because they died or didn't cooperate.There were 6 cases of squamous cell carcinoma,10 cases of adenocarcinoma, and 5 cases of small cell carcinoma.11 cases were with single lesion,10 cases were with multiple lesions,and with 42 lesions in all.All cases were underwent examination of MRS and DTI before treatment,1 day after treatment,1 week after treatment,1 month after treatment,3 months after treatment and 6 months after treatment. Contrast-enhanced MRI was undertaken before treatment,3 months after treatment and 6 months after treatment to get the precise change of metastatic volume.LINAC radiosurgery was undertaken by 6 MV X-ray,6-8Gy/F,1 day for interval,4-6 fractions in all,and in combination with WBRT.The therapeutic efficacy was evaluated 6 months after LINAC radiosurgery.Therapeutic efficacy was classified to complete response(CR),partial response(PR),stable disease(SD) and progressive disease(PD), and the metastases of PR,CR and SD belonged to efficacy significant group,as well as those of PD belonged to efficacy insignificant group.SPSS13.0 software was used for statistical analysis.The comparison of the examined values of MRS and DTI between the two groups was undertaken.The multiple stepwise linear regression was used to analysis the relevance between the tumor volume and the values.Results1,Application of MRS in evaluating the efficacy of patients with brain metastasis treated by radiotherapyThere was no interaction between the pathologic type and MRS values at different time points.Cho/Cr,Cho/nCho,Cr/nCr had significant difference between the effective group and the ineffective group(P<0.05).Cho/Cr ratio was over time in different trends between the two groups.The curves were opposite at 1 week to 1 month.The changing degree was 41.73%in the ineffective group and -19.84%in the effective group.The curves of Cho/nCho,Cr/nCr were different at 1 week.The changing degree was 96.92%,158.91%in the ineffective group and -7.14%,5.53%in the effective group respectively.There was a significant positive correlation between Cho,Cho/Cr,Cho/nCho and metastatic volume.That was to say the ratios would increase with the volume increase. Cho had the most significant relevance.2,Application of DTI in evaluating the efficacy of patients with brain metastasis treated by radiotherapyThere was no interaction between the pathologic type and DTI values at different time points.FA and rFA had significant difference between the effective group and the ineffective group.FA and rFA was over time in different trends between the two groups.The curves were opposite at 1 week to 1 month.The changing degree was 24.66%in the effective group,but did not change significantly in the ineffective group.There was a significant negative correlation between FA and the metastatic volume(r=-0.847,P=0.033).That was to say FA would decrease with the volume increase. Conclusion1,There was no interaction between the pathologic type and MRS and DTI values at different time points in brain metastasis from lung cancer.2,The value of Cho,Cho/Cr,and Cho/nCho would increase with the volume increase,but of FA would decrease with the volume increase.3,The change of the direction and degree of Cho/Cr and of FA 1 month after treatment was earlier than the change of volume,and could be used as the early indicators of the efficacy of radiotherapy.
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