The Effect Evaluation Of Radiotherapy To Brain Metastases With Diffusion Tensor Imaging

PurposeTo evaluate the clinical application and significance of multiparameter DTI quantitive analysis in curative effect and radiation injury of brain metastases after radiotherapy.Methods and materials15 cases of brain metastases that got pan-brain radiotherapy combined with X raying and finished at least 6 months' follow up were collected and the total foci were 44.The cases with single focus were 6 and that with multiple foci were 9.8 cases were female and 7 cases were male. The age range was from 33 to 76,which 47 on average. Routine MRI examination and DTI were both proceeded to measure ADC, FA value in-focus and peri-ventricle alba at the time of pre-radiotherapy, post-radiatherapy immediately and 1,3,6 months later. The data was treated with SPSS 11.5 software and total measurement data was shown by x|-±s.(α= 0. 05)Results1. MRI manifestation post-radiotherapyIn the whole 44 foci, 15 focis that were smaller than 1.5 cm became smaller and even disappeared at last; 24 ones got smaller but observed; 5 ones became bigger and obvious edema and mass effect were observed with ring or nodosity enhancement. One case got new metastases.2 cases got alba alteration and one case got worse in demyelination 3 month later. The demyelination got further worse 6 month later. 2. ADC, FA value change of DTI post-radiotherapyADC value rised gradually after radiotherapy at different stage. Compared with ADC value pre-radiotherapy, no statistically significant was found after radiotherapy immediately(p=0.563); ADC value rised obviously after 1,3,6 months and there was statistical significance. FA value got no statistical significance pre- or post-radiotherapy among the groups. In the 5 foci that got bigger, ADC value after 6 months was measured and, compared with that after 3 months, two ADC value rised and both showed relative higher ADC value, while the other 3 foci showed relative lower ADC value.FA value of peri-ventricle alba became lower after radiotherapy. Compared with pre-raidotherapy, FA value got lower after radiotherapy immediately without statistical significance(p=0.164);FA value got lower after 1,3,6 months with statistical significance. ADC value decreased after radiotherapy but rised when alba degeneration or demyelination worsening occurred without statistical significance still among groups.3. contrast analysis between MRI and DTI groupThe change of foci and peri-ventricle alba was detected 3 months after radiotherapy, while the change of ADC and FA value could be detected after radiotherapy immediately and the difference became obvious gradually as time proceeding. There was statistical significance in comparison by ADC and FA value pre-radiotherapy and post-radiotherapy.Conclusion1.The rising of ADC value in metastases focus could indicate early effect post-radiotherapy, but less valuation in tumor body evaluation.2.The descending of FA value in peri-ventricle alba after pan-brain radiotherapy was more sensitive than ADC value change in early prediction of radiation injury.3. In early stage of radiotherapy course, ADC and FA value measurement by DTI could better represent pathological change and evaluate early effect than routine MRI examination.