Applications Of ESWAN Technology Of Quantitative Estimation Of Regional Brain Iron In Patients With Restless Legs Syndrome

OBJECTIVE:The objective of this study was to use the transformed magnitudevalues—log(magnitude signal intensity) and relative magnitude signal intensity、phase and R2*value in ESWAN to evaluate brain iron content in patients withidiopathic restless legs syndrome (RLS) and healthy control groups. By Comparingthe transformed magnitude values, Phase and R2*values of brain iron contents of thered nucleus, substantia nigra pars compacta, substantia nigra pars reticulate, globuspallidus, putamen, caudate nucleus, dentate nucleus, and Thalamus measured by3.0TMR, and conducting bivariate correlation analyses with the International RestlessLegs Study Group-IRLSSG scores and the transformed magnitude values, Phase andR2*values of the brain regions of interest (ROIs) in RLS patients group for exploringthe sensitivity the brain iron contents measurement methods the value of magnitude,Phase and R2*imaging in the diagnosis of RLS.MATERIALSAND METHODS:Thirty-five RLS Patients (21women,14men; mean54years; and35sex-andage-matched controls were studied using gradient-echo imaging scanned by3.0TMagnetic Resonance scanner and human brain8channel coil. RLS was diagnosed byclinical interview based on symptoms that fulfilled the criteria established by theInternational RLS Study Group. Disease severity was scaled using the InternationalRLS Study Group Rating Scale (IRLS). The transformed magnitude value，Phase andR2*value analysis was performed on localized brain regions of interest selected onmagnitude，phase imaging and R2*imaging respectively, sensitive to paramagnetictissue. Scanning methods: positioning and then executing ESWAN and R2STAR axisscanning after conventional T2Flair sequences scanning. Measuring the magnitudephase and R2*values of interesting regions for each subjects by software（GE MedicalSystems, Functool4.4workstation）. Data Processing: An experienced radiology doctor who was blinded to clinical information manually outlined regions of interestbilaterally. Interval three month, repeating measurements of the above mentionedregions by the same doctor, a total of three times. The average of three measurementsrepresented the final magnitude，phase and R2*values of the red nucleus, substantianigra pars compacta, substantia nigra pars reticulate, globus pallidus, putamen,caudate nucleus, dentate nucleus, and thalamus. Differences between the2subjectgroups were was assessed with the unpaired double-tailed Student t test. Therelationship between the transformed magnitude value, phase and R2*value andIRLS scores, was studied using the [Pearson correlation coefficient. ReceiverOperating Characteristic was drawn to assess these indexes the value in diagnosis ofRLS.RESULTS:Compared with the normal control group:1.The log(magnitude signal intensity)values of red nucleus, substantia nigra pars compacta, substantia nigra pars reticulate,globus pallidus, and dentate nucleus showed elevated, between the RLS group and thecontrol group had statistically difference (P <0.05), but the putamen, caudate nucleus,and thalamus between the groups had no statistically difference.2. The relativemagnitude signal intensity values of red nucleus, substantia nigra pars compacta,substantia nigra pars reticulate, and globus pallidus showed elevated, between theRLS group and the control group had statistically difference (P <0.05), but theputamen, caudate nucleus, dentate nucleus, and thalamus between the groups had nostatistically difference.3. The phase values of red nucleus, substantia nigra parscompacta, and thalamus showed elevated, between the RLS group and the controlgroup had statistically difference (P <0.05), but the substantia nigra pars reticulate,globus pallidus, dentate nucleus, putamen, and caudate nucleus between the groupshad no statistically difference.4. The R2*values of red nucleus, substantia nigra parscompacta, substantia nigra pars reticulate, globus pallidus, and dentate nucleusshowed elevated, between the RLS group and the control group had statisticallydifference (P <0.05), but the putamen, caudate nucleus, thalamus between the groupshad no statistically difference. The log(magnitude signal intensity) values of RLS group positively correlatedwith IRLS scores； Their correlation coefficients were1. red nucleus0.836；2.substantia nigra pars compacta0.763；3. substantia nigra pars reticulata0.729；4.globus pallidus0.507；5. putamen0.604；6. caudate nucleus0.735；7. dentate nucleus0.689；8. thalamus0.797respectively. The phase value of thalamus of RLS grouppositively correlated with IRLS scores；Their correlation coefficients were0.399.Thearea under the ROC curve(AUC) of the log(magnitude signal intensity) values ofthalamus best was0.949,when the value was3.36, the sensitivity was100%,and thespecificity was76.2%.CONCLUSION:By analyzing the transformed magnitude values、phase and R2*values of the rednucleus, substantia nigra pars compacta, substantia nigra pars reticulate, globuspallidus，putamen, caudate nucleus, dentate nucleus, thalamus in idiopathic RLS, Ourresults support the hypothesis of reduced, substantia nigra pars compacta, globuspallidus, dentate nucleus lower brain iron content in RLS patients, which may have animportant role in the pathophysiology of the disorder. This study revealed that thetransformed magnitude values and the R2*values was more sensitive than Phasevalues and R2*values for the diagnosis of RLS. To some extent，we could make aquantitative assessment of brain iron deposition by ESWAN in RLS patients.Magnetic resonance ESWAN technology could play a constructive role in vivodiagnosis of RLS disease and duration of monitoring.