The Application Of Synthetic MRI In The Study Of Leukoaraiosis

Objective:Synthetic MRI could provide quantitative T1,T2,PD values in leukoaraiosis(LA)lesions besides the volume information which has been widely used in the studies of white matter diseases.This study set out to demonstrate the validity of quantifying LA by relaxometric characteristics from Synthetic MRI.Furthermore,we aimed to investigate the association of LA with small vascular cerebral diseases(Csvds)and large vessel atherosclerosis.Materials and Methods:One hundred and thirty-one patients with acute cerebral vascular symptom were enrolled in this study.All participants underwent the conventional Bravo,CUBE FLAIR,and Synthetic MRI with a 3.0T MR system(SIGNA Pioneer,GE Healthcare,Milwaukee,WI).In order to extract LA lesions,firstly,we used dcm2niigui software to convert SyT2FLAIR,SyT1W,Bravo,CUBE FLAIR,SyT1map,SyT2map and SyPDmap to NII format,and then used MATLAB(R2016B version)software with image segmentation tool(LST,version 2.0.4)and lesion growth model(Bravo image is used as a reference and the threshold is 0.1)to process SyT2FLAIR and SyTlW images,by which LA lesions were preliminarily automately extracted from SyT2FLAIR images.Due to the inconsistency between SyT2FLAIR and traditional FLAIR images,MATLAB(version R2016B)was used to register the CUBE FLAIR image to the SyT2FLAIR image acting as a reference to manually adjust the lesion area.At last,the SyT1 map,SyT2 map,and SyPD map were matched to the SyT2FLAIR image with LA lesions extracted so that the map image of LA could be obtained.The absence or presence of lacune and cerebral microbleeds(CMBs)were rated based on CUBE FLAIR and T2*WI images.Intracranial or Extracranial atherosclerosis stenosis(ICAS or ECAS)was defined as lumen narrowing more than 50%on MRA or CTA.Spearman correlation was conducted to analyze the association of LAVR with T1 T2,and PD value,respectively.T test,chi-square test and multivariable logistic regression analysis were performed to determine the correlation of LAVR with Csvds and ICAS or ECAS after adjusting for potential confounding factors.Results:LAVR demonstrated a positive association with T2 value,a negative association with T1 value,but no association with PD value.In the multivariable regression analysis,LAVR was independently correlated with age(OR=1.13;95%CI=1.07-1.20;P<0.001),lacune(OR=3.03;95%CI=1.17-7.87;P=0.022)and CMBs(OR=6.95;95%CI=1.59-30.45;P=0.01).A statistical significance was found in both age(OR=1.10;95%CI=1.05-1.15;P<0.001)and lacune(OR=2.43;95%CI=1.01-5.83;P=0.047)with T2 value of LA.There was a significant relationship between lacune and PD value of LA(OR=2.81;95%CI=1.24-6.35;P=0.013).While,age,lacune and CMBs were not associated with T1 value of LA(P=0.668,0.994 and 0.282,respectively).Furthermore,we also found that ICAS and ECAS were not associated with T1,T2,PD value of LA and LAVR(P=0.588,0.75,0.506 and 0.14,respectively).Conclusion:Synthetic MRI could simultaneously provide quantitative measurements of T1,T2,and PD value and the volume information of LA.The correlation of LA with lacune and CMBs rather than with ICAS or ECAS suggests that LA may be a kind of Csvds,which shares a common pathological mechanism with lacune and CMBs.Further studies are needed to validate our results and explore their clinical significances with a larger sample size.