Functional Magnetic Resonance Imaging Of Early Radiation-induced Brain Injury After Radiotherapy For Nasopharyngeal Carcinoma

Part I The early changes of DTI in the temporal lobe after radiotherapy for nasopharyngeal carcinoma and its correlation with the changes of neurocognitive functionObjective To investigate the early changes of MRI diffusion tensor imaging(DTI)and its correlation with neurocognitive function after radiotherapy for nasopharyngeal carcinoma(NPC).Materials and methods Data were collected from 35 patients with nasopharyngeal carcinoma who were followed up for one year from December 2014 to August 2016.We use magnetic resonance scanner HDxt3.0T made in General Electric.DTI was performed in the patients before radiotherapy(G0 group),0-3 months after radiotherapy(G1 group),3-6 months(G2 group)and 6-9 months(G3 group)in our hospital after radiotherapy.And Mo CA scale score of the patients before the start of the examination.The ROI were on both sides of the hippocampus near temporal lobe,such as the measurement of FA value,radical eigenvalue,and perpendicular eigenvalue.Longitudinal comparison was taken.And single factor analysis of variance difference between both sides of hippocampus was taken in radiotherapy comparison of each time node,and the horizontal comparison between the four groups.Then compare these three DTl parameters of the four groups with TBSS.We analyzed the correlation with the neurocognitive function of Mo CA scale score.Results Mo CA scores were greater than 26 in all the patients before radiotherapy,belongs to the normal range after radiotherapy.With time step by step,the overall trend in the Mo CA score decreased.After 6 months,the score remained stable at around 24 level.F value of Mo CA score between the four groups was 48.92,P<0.0001.On both sides of the hippocampus of brain white matter,after radiotherapy within 3 months,the FA value decreased,from 3 months to 6 months,the FA value gradually increased,6 months later,the increase amplitude became slow,but still lower before radiotherapy.In the left hippocampus area between the four groups,the F value=2.29,P=0.0807,P >0.05,was not statistically significant.F value =3.27,P =0.0233,P <0.05,in the right hippocampus area between the four groups was statistically significant.The change is similar to radical eigenvalue.In the left hippocampus in four groups,F=0.79,P =0.5035,P >0.05,data were not statistically significant.F value of =2.86,P =0.0394,P <0.05,in the right hippocampus area between the four groups was also statistically significant.The perpendicular eigenvalue in patients after radiotherapy was significantly increased within 3 months.From 3 months to 6 months,λ⊥ decreased gradually,6 months later,decrease slowed down,but still higher than the level before treatment.In the left hippocampal area between the four groups,F=7.74,P =0.0001,P <0.05.And in the right hippocampus region,F=9.71,P <0.0001,P <0.05.The differences were statistically significant.Multiple logistic regression analysis of Mo CA and several DTI parameters showed that c2=106.92,OR=0.281,P<0.001.Conclusion(1)FA value、λ∥、λ丄 of temporal lobe and hippocampal area in nasopharyngeal carcinoma patients after radiotherapy appeared abnormal changes,and had the correlation with neurocognitive function;(2)λ丄 seems more sensitivity to reflect the subtle changes in brain structure injury after radiotherapy,suggesting demyelinating diseases exist.Part II Early changes of 1H-MRS and its correlation with neurocognitive function after radiotherapy for nasopharyngeal carcinomaObjective To analyze the early changes of 1H-MRS in hippocampus region of temporal lobe after radiotherapy of nasopharyngeal carcinoma and its correlation with neurocognitive function.Materials and methods Data were collected from 26 patients with nasopharyngeal carcinoma who were followed up for one year from December 2014 to August 2016.We use magnetic resonance scanner HDxt3.0T made in General Electric.MRS was performed in the patients before radiotherapy(G0 group),0-3 months after radiotherapy(G1 group),3-6 months(G2 group)and 6-9 months(G3 group)in our hospital after radiotherapy.We measured on both sides of the hippocampus adjacent to temporal lobe about Cho,Cr,NAA,NAA/Cho and NAA/Cr ratio.And single factor analysis of variance difference between both sides of hippocampus was taken in radiotherapy comparison of each time node,and the comparison between the four groups.Also we analyzed the correlation with the neurocognitive function of Mo CA scale score.Results On both sides of hippocampus at the beginning of nasopharyngeal carcinoma after radiotherapy within 3 months,the Cho value increased,NAA value decreased,then Cho and NAA values were slowly returned to the level before radiotherapy,but still lower before radiotherapy.Between the four groups on the left side of the Cho F-measure=1.86,P =0.141.Cho on the right side of the F-measure=1.11,P=0.3496.Left hippocampus region of NAA F-measure=1.34,P =0.266.NAA on the right side of the F-measure=0.84,P =0.4775.And Cr value is stabilized,the left F-measure=0.00,P =0.9998,right F-measure=0.01,P =0.999.With all of them,P >0.05,the data were not statistically significant.The value of NAA/Cho after radiotherapy within 3 months decreased.From 3 months after 6 months,the ratio increased gradually.6 months later,the increase amplitude was smaller,but still lower before the treatment.Between the four groups on the left side of F-measure=14.36,P <0.0001,on the right side of F-measure=10.34,P <0.0001.NAA/Cr value was similar with NAA/Cho between the four groups.On the left side of F-measure=5.28,P =0.002,P <0.05,right F-measure =2.85,P =0.041,P <0.05,data were statistically significant.F value of Mo CA score between the four groups was 37.67,P<0.0001.Multiple logistic regression analysis of Mo CA and several MRS parameters showed that c2=86.65,OR=0.277,P<0.001.Conclusion(1)NAA/Cho and NAA/Cr value after radiotherapy of nasopharyngeal carcinoma in hippocampus region showed dynamic changes,and were associated with neurocognitive function reducing;(2)NAA/Cho can predict the changes of metabolism of brain injury after radiotherapy at different time nodes.Part III The early changes of DSC-PWI parameters and its correlation with neurocognitive function after radiotherapy for nasopharyngeal carcinomaObjective To investigate the changes of regional cerebral blood flow and blood volume in the hippocampus region of temporal lobe after radiotherapy for nasopharyngeal carcinoma.Materials and methods Data were collected from 35 patients with nasopharyngeal carcinoma who were followed up for one year from December 2014 to August 2016.We use magnetic resonance scanner HDxt3.0T made in General Electric.DSC-PWI was performed in the patients before radiotherapy(G0 group),0-3 months after radiotherapy(G1 group),3-6 months(G2 group)and 6-9 months(G3 group)in our hospital after radiotherapy.We measured on both sides of the hippocampus adjacent to temporal lobe about r CBF and r CBV values.And single factor analysis of variance difference between both sides of hippocampus was taken in radiotherapy comparison of each time node,and the comparison between the four groups.Also we analyzed the correlation with the neurocognitive function of Mo CA scale score.Results Before and after radiotherapy in patients with nasopharyngeal carcinoma,the P value of r CBF and r CBV were all less than 0.0001.r CBF value of the left F=41.59,r CBF value of the right F=42.57,the left r CBV value of F=9.07,the right r CBV value of F=10.17.A further comparison between four groups were undertaken.0-3 months after the radiotherapy the r CBF and r CBV values decreased most obviously,while r CBF decline more significantly than r CBV.3-6 months after radiotherapy,the r CBF value and r CBV value increased,but still significantly lower than that before the treatment.6-9 months after radiotherapy,r CBF value and r CBV value increased further,the increase amplitude became slow,but still lower before the treatment.F value of Mo CA score between the four groups was 48.92,P<0.0001.Multiple logistic regression analysis of Mo CA and PWI parameters showed that c2=111.10,OR=0.313,P<0.001.Conclusion(1)The r CBF in temporal lobe hippocampus region at different time points after radiotherapy for nasopharyngeal carcinomawas significantly higher than that of r CBV,and the two parameters were correlated with the decrease of neurocognitive function.(2)The value of r CBV was able to predict the changes of brain function caused by brain injury after radiotherapy for nasopharyngeal carcinoma.This prompted the possibility of microvascular injury at different time points.Part IV Sensitivity prediction of early changes of f MRI parameters after radiotherapy for nasopharyngeal carcinomaObjective To analyze the changes of magnetic resonance function imaging parameters in the temporal regions of bilateral hippocampus after radiotherapy of nasopharyngeal carcinoma.Through the time node determination and threshold determination to investigate the feasibility of early diagnosis of radiation-induced brain injury.Materials and methods Data collected from the above four part of nasopharyngeal carcinoma patients.We underwent the magnetic resonance scans with patients before radiotherapy(G0 group),0-3 months after radiotherapy(G1 group),3-6 months(G2 group)and 6-9 months(G3 group)in our hospital after radiotherapy.The results have significant importance above about λ⊥,NAA/Cho ratio,r CBV value.With these parameters between groups of radiotherapy for low radiation side and high radiation side comparing,we analysized the functional magnetic resonance parameters and early prediction index during different reaction period in nasopharyngeal carcinoma before and after radiotherapy.The ROC curve analysis of the early prediction index was used to determine the threshold value.Results Each group of patients before and after radiotherapy for nasopharyngeal carcinoma radiotherapy compared low side and high side level,λ⊥ in 3 months after radiotherapy with F-measure =5.787,P value =0.022,P<0.05,3-6 months with F-measure =5.787,P value =0.022,P<0.05,6-9 months with F-measure =5.787,P value =0.022,P<0.05.And the results of NAA/Cho on both sides in G1 group was that F-measure =2.749,P =0.110,P>0.05,in G2 group with F-measure =1.404,P value =0.247,P>0.05,in G3 group with F-measure =0.955,P=0.338,P>0.05;The perfusion parameters of r CBV on both sides of contrast in the G1 group was that F-measure =0.018,P=0.895,in G2 group with F-measure =0.134,P=0.716,in G3 group with F-measure =0.352,P=0.557.The P value were all more than 0.05.The difference was not statistically significant.The area under the ROC curve was 0.583±0.040,P=0.043,and the 95% confidence interval of the area was 0.509-0.717.The diagnostic threshold is 3.51-3.54.Conclusion(1)The value of λ⊥ appeared the changes in early 3 months in patients with nasopharyngeal carcinoma after radiotherapy.It was sensitive that the diagnostic threshold is 3.51-3.54.This indicates the possibility of early radiation-induced brain injury demyelination exists;(2)Although the ratio of NAA/Cho and r CBV value were possible to predict the changes of brain function caused by brain injury after radiotherapy of nasopharyngeal carcinoma,but they could not determine the specific time node of the change,and it was impossible to determine the possibility of radiation brain injury by threshold value.