Objective To retrospectively analyze the changes in cerebral blood flow(CBF)of hippocampus before and after radiotherapy(RT)and to explore its relationship with dose for providing a feasible approach for dynamically monitoring hippocampal response after whole brain radiation therapy in patients with brain metastases(BMs).Methods A retrospective analysis was conducted on magnetic resonance(MR)images from 43 BMs patients before and after RT,including T1-weighted imaging(T1WI)and three-dimensional arterial spin labeling(3D-ASL)imaging.Manual segmentation of the hippocampal structures was performed on T1WI to determine hippocampal volume,while CBF within the hippocampus was derived from 3D-ASL images.Patients were categorized into different groups according to the time interval between two MR scans and the dose received by the hippocampus,namely short time interval[<30 d,with an average of(19.74±7.15)d]≤1 Gy,1-30 Gy and≥30 Gy groups;long time interval[>3 months,with an average of(495.50±226.06)d]≤1 Gy,1-30 Gy and≥30 Gy groups.The patterns of changes in hippocampal CBF and volume,as well as the dose-effect relationship following RT were analyzed.Results(1)A total of 86 hippocampi were enrolled,showing reductions of 8.32%in minimum CBF(CBF-min),7.31%in maximum CBF(CBF-max),8.09%in mean CBF(CBF-mean),and 4.11%in hippocampal volume after RT(P<0.05).The decrease rates of CBF-min,CBF-max and CBF-mean were 6.33%,7.01%and 8.23%higher than the reduction rate of hippocampal volume,respectively.(2)With a brief interval between two MR simulation localization scans,hippocampal CBF in the groups receiving≤1 Gy and 1-30 Gy exhibited an increase,with the increase rate positively correlated to the radiation dose absorbed by the hippocampus.Conversely,in the group receiving≥30 Gy,hippocampal CBF decreased.The variations in the rate of hippocampal CBF change across the dose groups were statistically significant,except when comparing≤1 Gy and 1-30 Gy groups(P<0.05).Additionally,the hippocampal volume in all 3 dose groups experienced a slight increase,with the growth rate also positively correlated to the radiation dose received by the hippocampus;however,these differences were not statistically significant(P>0.05).(3)With a long interval between MR simulation localization scans,both hippocampal CBF and volume in all 3 dose groups demonstrated decreasing trends,with the decrease rate positively correlated to the radiation dose received by the hippocampus.Statistically significant differences in the rate of CBF change were noted among the dose groups,except for the comparison between≤1 Gy and 1-30 Gy groups(P<0.05).The reduction rate of hippocampal volume across 3 dose groups was statistically significant(P<0.05).Conclusion The reduction in hippocampal CBF following RT in BMs patients is more sensitive than the reduction in hippocampal volume,exhibiting a pronounced dependence on both time and radiation dose.Consequently,CBF changes should be employed as a standard bioindicator for monitoring the response to hippocampal RT and predicting radiological injuries after whole brain radiotherapy in BMs patients.

Objective To retrospectively analyze the changes in cerebral blood flow(CBF)of hippocampus before and after radiotherapy(RT)and to explore its relationship with dose for providing a feasible approach for dynamically monitoring hippocampal response after whole brain radiation therapy in patients with brain metastases(BMs).Methods A retrospective analysis was conducted on magnetic resonance(MR)images from 43 BMs patients before and after RT,including T1-weighted imaging(T1WI)and three-dimensional arterial spin labeling(3D-ASL)imaging.Manual segmentation of the hippocampal structures was performed on T1WI to determine hippocampal volume,while CBF within the hippocampus was derived from 3D-ASL images.Patients were categorized into different groups according to the time interval between two MR scans and the dose received by the hippocampus,namely short time interval[<30 d,with an average of(19.74±7.15)d]≤1 Gy,1-30 Gy and≥30 Gy groups;long time interval[>3 months,with an average of(495.50±226.06)d]≤1 Gy,1-30 Gy and≥30 Gy groups.The patterns of changes in hippocampal CBF and volume,as well as the dose-effect relationship following RT were analyzed.Results(1)A total of 86 hippocampi were enrolled,showing reductions of 8.32%in minimum CBF(CBF-min),7.31%in maximum CBF(CBF-max),8.09%in mean CBF(CBF-mean),and 4.11%in hippocampal volume after RT(P<0.05).The decrease rates of CBF-min,CBF-max and CBF-mean were 6.33%,7.01%and 8.23%higher than the reduction rate of hippocampal volume,respectively.(2)With a brief interval between two MR simulation localization scans,hippocampal CBF in the groups receiving≤1 Gy and 1-30 Gy exhibited an increase,with the increase rate positively correlated to the radiation dose absorbed by the hippocampus.Conversely,in the group receiving≥30 Gy,hippocampal CBF decreased.The variations in the rate of hippocampal CBF change across the dose groups were statistically significant,except when comparing≤1 Gy and 1-30 Gy groups(P<0.05).Additionally,the hippocampal volume in all 3 dose groups experienced a slight increase,with the growth rate also positively correlated to the radiation dose received by the hippocampus;however,these differences were not statistically significant(P>0.05).(3)With a long interval between MR simulation localization scans,both hippocampal CBF and volume in all 3 dose groups demonstrated decreasing trends,with the decrease rate positively correlated to the radiation dose received by the hippocampus.Statistically significant differences in the rate of CBF change were noted among the dose groups,except for the comparison between≤1 Gy and 1-30 Gy groups(P<0.05).The reduction rate of hippocampal volume across 3 dose groups was statistically significant(P<0.05).Conclusion The reduction in hippocampal CBF following RT in BMs patients is more sensitive than the reduction in hippocampal volume,exhibiting a pronounced dependence on both time and radiation dose.Consequently,CBF changes should be employed as a standard bioindicator for monitoring the response to hippocampal RT and predicting radiological injuries after whole brain radiotherapy in BMs patients.

Objective:To analyze the clinical characteristics of elderly acute pulmonary thromboembolism(APE)patients complicated with preexisting atrial fibrillation(AF)and the impact of preexisting AF on in-hospital adverse outcomes in elderly patients with APE.Methods:A retrospective analysis was performed on elderly APE patients with preexisting AF hospitalized in Beijing Anzhen Hospital, Capital Medical University between January 1, 2008 and December 31, 2021.We compared the comorbidities, symptoms, signs, laboratory test results and echocardiographic features, simplified pulmonary embolism severity index(sPESI)scores and adverse in-hospital outcomes between the preexisting AF group and the non-AF group.Logistic regression was used to analyze the risk factors of in-hospital adverse outcomes in elderly patients with APE.Results:A total of 240 patients diagnosed with APE were enrolled.There were 120 patients in the AF group and 120 patients in the non-AF group.For patients in the AF group and the non-AF group, the proportions with chronic heart failure were 38.3%(46/120)and 15.8%(19/120), the proportions with lower extremity deep vein thrombosis(DVT)were 36.7%(44/120)and 65.8%(79/120), the left ventricular ejection fractions(LVEF)were(59±10)% and(62±7)%, and hospital stays were(15±7)and(11±4)days, respectively, and the differences were statistically significant( χ2=15.381, 20.429, t=2.527, -4.710, all P<0.05). The incidences of in-hospital adverse outcomes in the AF group and the non-AF group were 4.2%(5/120)and 3.3%(4/120), respectively, with no significant difference( χ2=0.000, P=1.000). The overall incidence of in-hospital adverse outcomes was 3.8%(9/240). Multivariate Logistic regression analysis showed that elevated lactic acid was an independent risk factor for in-hospital adverse outcomes( OR=2.753, 95% CI: 1.367-5.542, P=0.005). However, AF( OR=2.880, 95% CI: 0.587-14.141, P=0.192)and sPESI score( OR=2.056, 95% CI: 0.904-4.673, P=0.086)were not associated with in-hospital adverse outcomes. Conclusions:Elderly APE patients with preexisting AF have a relatively low incidence of DVT, but a higher proportion have concurrent chronic heart failure and need a longer hospital stay.Elevated lactic acid is an independent risk factor for in-hospital adverse outcomes of elderly APE patients with preexisting AF.However, preexisting AF has no predictive value for in-hospital adverse outcomes in elderly patients with APE.