The Application Of Arterial Spin Labeling In Viral Encephalitis

Objective: To explore the value of MRI arterial spin-labeling (ASL)perfusion imaging in diagnosing viral encephalitis. For conveniently, useencephalitis instead of viral encephalitis.Methods:10controls and40patients (30diagnosed as encephalitis and10diagnosed as meningitis) were enrolled in this study. All of the cases wereperformed by magnetic resonance imaging (MRI) and flow sensitivealternating inversion recovery (FAIR) which is one of ASL technique. Finally,selected the regions of interest in the relative cerebral blood flow (rCBF) maps.In volunteers and patients with meningitis, selected the regions of interest withconventional T1WI as a background anatomy figure, which include the whitematter, gray matter, thalamus, basal ganglia, hippocampi, and insula. Patientswith encephalitis, selected the regions of interest with conventional T2FLAIRimage as a background anatomy figure, which include the lesions and themirror zones. Relative cerebral blood flow△M obtained from theabove-mentioned regions were divided into a control group, a meningitisgroup and an encephalitis group, then used the SPSS statistical software to testthe differences among the groups. For the encephalitis group, used thepaired-samples t-test to test the differences of△M between the lesions and themirror zones.Results: All of cases were obtained clear rCBF maps. In the volunteers,different cerebral blood flow of gray and white matter determined with FAIRwere clearly observed, the CBF of gray matter obviously higher than that ofwhite matter. The perfusion of the white matter, gray matter, thalamus, basalganglia, hippocampi and insula were no significant differences betweenmeningitis and healthy controls group (P＞0.05), and the differences of gray matter between two groups was the largest (P=0.16). In the encephalitis group,the perfusion of the lesions locating at gray matter were higher than that of thenormal gray matter in healthy controls group(P＜0.05), but the perfusion ofother regional lesions and normal brain tissue were no obvious differences(P＞0.05). In the encephalitis group, the perfusion of the lesions locating at graymatter were higher than that of the mirror areas(P＜0.05), but the perfusion inother areas were no significant differences(P＞0.05).Conclusion: Patients with encephalitis, the lesions locating in graymatter presented hyperperfusion and white matter and other parts with nochange, indicating that these parts had different pathological changes. It isconvenient to provide some reference for diagnosing the encephalitis andevaluating the therapeutic effect, because ASL is completely non-invasive. Objective: To explore the value of MRI arterial spin-labeling (ASL)perfusion imaging in the different periods of viral encephalitis, and to confirmthat the perfusion in the different periods were different.Methods:10controls and30patients who diagnosed as encephalitisclinically were enrolled in this study. According to the first appearingneurological symptoms in14days as the boundary, divided the patients withencephalitis into acute phase group (18cases) and non-acute phase group (12cases). All of the cases were performed by magnetic resonance imaging (MRI)and flow sensitive alternating inversion recovery (FAIR) which is one of ASLtechnique. Finally, selected the regions of interest in the relative cerebral bloodflow (rCBF) maps. In volunteers, the regions of interest with conventionalT1WI as a background anatomy figure, which include the white matter, graymatter, thalamus, basal ganglia, hippocampi, and insula. Patients with encephalitis, the regions of interest with conventional T2FLAIR image as abackground anatomy figure, which include the lesions and the mirror zones.Relative cerebral blood flow△M obtained from the above-mentioned regionswere divided into a control group, an acute phase group and a non-acute phasegroup, then used the SPSS statistical software to test the differences among thegroups. For the acute phase group and the non-acute phase group, used thepaired-samples t-test to test the differencess of△M between the lesions andthe mirror zones.Results: All of cases were obtained clear rCBF maps. There weresignificant differencess in the perfusion of the lesions locating at gray matterand insula between the acute phase and non-acute phase group(P＜0.05). theperfusion of the acute phase group was higher than that of the non-acute phasegroup, but the perfusion of other regional lesions were no obvious differencesbetween two groups(P＞0.05). In the acute phase group, the perfusion of thelesions locating at gray matter, insula and hippocampi were higher than that ofthe normal gray matter, insula and hippocampi in healthy controls group(P＜0.05), but the perfusion of other regional lesions and normal brain tissue wereno obvious differences(P＞0.05). In the non-acute phase group, the perfusionof the lesions locating at gray matter were lower than that of the normal graymatter in healthy controls group(P＜0.05), but the perfusion of other regionallesions and normal brain tissue were no obvious differences(P＞0.05). In theacute phase group, the perfusion of the lesions locating at gray matter,hippocampus and insula were higher than that of the mirror areas(P＜0.05),but the perfusion in other areas were no significant differences(P＞0.05). Inthe non-acute phase group, the perfusion of the lesions locating at gray matterwere lower than that of the mirror areas(P＜0.05), but the perfusion in otherareas were no significant differences(P＞0.05).A patient with the acute phase encephalitis, T1WI and T2WI showed noobvious abnormalities, and the left temporal lobe slight swelling in T2FLAIRimage. FAIR function map showed high perfusion at the left temporal lobe andleft frontal lobe. Conclusion: Hyperperfusion which located at gray matter, hippocampiand insula in the acute phase encephalitis contributed to diagnosing andtreating in early time, improving the prognosis. It also was used to evaluate thetherapeutic effect. For some patients with the acute phase of encephalitis,FAIR function map shows lesions best in conventional MRI and enhancement,so this phenomenon needs to be studied further.