Room: AAPM ePoster Library
Purpose: quantitatively analyze the changes in blood perfusion in brain metastases (BMs), normal brain areas and peritumor edema areas during radiotherapy (RT) using MR 3D ASL for BMs patients. The relationships between perfusion changes in these three brain regions and RT dose gradients will be established to provide a reference for the individualized RT for BMs patients.
Methods: simulated location images of 26 BMs patients before and after RT were collected The high signal areas of BMs in contrast enhanced T1W images, normal brain areas and peritumor edema areas were defined as regions of interest(ROIs) respectively. The changes and correlation of the mean maximum cross-sectional area and the mean maximum cerebral blood flow (CBF) in BMs tumor target areas before and after RT were studied. The changes of CBF values in three ROIs under different dose gradients were analyzed.
Results: mean maximum cross-sectional area and CBF value of BMs decreased by 26.46% and 29.64% respectively after RT(both P<0.05).The decreasing rates of CBF of BMs at 30~40?40~50Gy and > 50Gy dose gradients were 33.75%, 24.61% and 27.55%, respectively(all P<0.05).In normal brain areas, under the dose gradient of 0~10?10~20?20~30?30~40?40~50Gy and > 50Gy, the decreasing rates of CBF after RT were 7.65%?11.12%?18.42%, 20.23%?19.79% and 17.89%, respectively(all P<0.05). The decreasing rates of CBF in peritumor edema areas elevated as dose gradients increased after RT. The perfusion changes of BMs before and after RT were more notable than those in normal brain areas and peritumor edema areas.
Conclusion: MR 3D ASL can objectively reflect the changes of perfusion in BMs, normal brain areas and peritumor edema areas, According to the CBF variations, it is recommended to control the dose of normal brain areas below 30Gy, whereas tumor target areas with high perfusion and peritumor edema areas should be given a high dose.
Not Applicable / None Entered.