Application Of Three Dimensional Arterial Spin Labeling Perfusion In The Diagnosis Of Acute Stage Of Viral Encephalitis In Children

Objective:To evaluate the value of three dimensional arterial spindle-labeled perfusion in the diagnosis of acute viral encephalitis in children.Methods:In this study,Twenty patients with viral encephalitis of children admitted to the department of pediatric neurology of our hospital from March 2018 to February 2020 and 20 healthy volunteers of similar age were selected to be included in the study.They were divided into the patient group and the healthy control group.All the children in the patient group completed the first examination in the acute period(<14 days),and some of them were reexamined after treatment.All subjects underwent conventional MRI and three dimensional arterial spin labeling(3D ASL),and analyzed clinical symptoms,first-diagnosis image features and changes of reexamination images.Empirical visual evaluation of cerebral blood flow(CBF)pseudo-color map,measurement of the lesion area and normal cerebellar hemisphere CBF value,the calculation of standardized cerebral blood flow value(nCBF),the acute phase of the first diagnosis group was compared with the follow-up group,the healthy control group.ROC curve of CBF value and nCBF value in diagnosing children viral encephalitis was plotted to find the optimal critical value.Results:All the 20 children with viral encephalitis in the patient group completed the first MRI in the acute stage(within 14 days of onset).A total of 11 reexaminations were conducted on 9 children,including 7 reexaminations in the acute phase(<14 days)and 4 reexaminations in the non-acute phase(14 days).In children with viral encephalitis,the routine MRI sequence in the acute stage presents single or multiple lesions,bilateral asymmetry,presenting as localized patchy or large patchy abnormal signals.The affected areas mainly include the temporal lobe,frontal lobe,parietal lobe and insula,hippocampal region and basal ganglia,thalamus and brainstem.Most of the lesions were irregular in shape,and most of them had no obvious placeholder effect.A few of them showed swelling of the gyrus.T2/FLAIR and DWI sequences were better than conventional MRI sequences,with higher positive rate and better detection of early small lesions.The values of CBF and nCBF in each group were measured by 3D ASL perfusion imaging.Acute response group:1.63±0.51;Non-acute response group:1.21±0.43.The nCBF value of the first diagnosis group was significantly higher than that of the follow-up group(1.63±0.51)and the control group(1.36 ± 0.19),and the difference was statistically significant.According to ROC curve analysis,nCBF value of 3D ASL is more valuable in the diagnosis of acute stage of viral encephalitis in children.When the threshold of nCBF was 1.84,the Youden index was the highest for the diagnosis of viral encephalitis in children,and this threshold could be used as a reference for the diagnosis of acute viral encephalitis in children.The 3D ASL examination of 9 patients after treatment showed dynamic changes of perfusion and decreased perfusion with time.Conclusion:Magnetic resonance dimensional arterial spin labeling perfusion technique can obtain normalized cerebral blood flow(nCBF)value by semi-quantifying method,which can accurately reflect the changes of microcirculation blood perfusion in the brain tissue of children with viral encephalitis in the acute stage,and is a feasible quantitative technique to improve the diagnostic efficiency of children with viral encephalitis.It has potential application value in evaluating curative effect and monitoring prognosis of children viral encephalitis.