Studies Of The Abnormalities Of Lesions And Normal-appearing White Matter In Patients With Relapsing-remitting Multiple Sclerosis Using Intravoxel Incoherent Motion MRI And Dynamic Contrast-enhanced MRI

ObjectiveRelapsing-remitting multiple sclerosis(RRMS)is the most common chronic and degenerative disease of the central nervous system,which is usually characterized by recurrent episodes of immune-mediated demyelination and is the main cause of non-traumatic neurological disability in young adults.Intravoxel incoherent motion(IVIM)is the microscopic translational movement occurring in each image voxel during an MRI acquisition,which can reflect the diffusion and perfusion characteristics of microvascular.Although this technology has been developed rapidly,rarely used in RRMS.Dynamic contrast-enhanced T1-weighted magnetic resonance imaging(DCE-MRI)is a promising non-invasive imaging method that enables the quantification of the abnormality of subtle microvascular environment and is increasingly used to estimate permeability in situations with BBB leakage,but also less inMS.The aim of the present study was to investigate the application value of using IVIM and DCE-MRI with the Patlak model to measure the microvascular permeability,diffusion and perfusion characteristics and the hemodynamic abnormalities of the lesions and NAWM in patients with RRMS.Materials and Methods27 patients with clinically definite RRMS underwent the conventional MRI and IVIM MRI based on multi-b-factor(b values of 10,20,30,40,50,100,150,200,350,500,650,800,1000 s/mm2)with 3.0T MR scanner.The apparent diffusion coefficient(ADC),ADCslow,ADCfast and f values were evaluated to reflect the diffusion and perfusion status of RRMS lesions and normal-appearing white matter(NAWM)regions.23 patients with clinically definite RRMS underwent the conventional MRI and the DCE-MRI with 3.0T MR scanner.Postprocessing was performed using a Patlak model.Quantitative measurement of the MR imaging biomarkers,including volume transfer constant(Ktrans)and blood plasma volume per unit volume of tissue(Vp)and perfusion parameters,including cerebral blood flow(CBF)and cerebral blood volume(CBV)of the lesions and NAWM regions.Results1)The nonenhancing(NE)lesions showed significantly higher ADC,ADCslow,ADCfast(H1= 46.16,H2= 27.32,H3= 8.93,P < 0.05)but lower fvalues(H= 17.99,P < 0.05)than that of the NAWM regions both near and far from NE lesions.However,The ADC,ADCslow,ADCfast and f values of the NAWM regions close to the NE lesions had no significant differences with the NAWM regions far from the lesions.2)The MR imaging biomarker Ktrans of NE lesions were significantly higher(χ2 = 7.58,P < 0.05)than that of the NAWM regions far from NE lesions,but there were no significant differences between the NE lesions and NAWM regions close to the lesions.3)In NE lesions,the CBV were significantly higher(χ2 = 6.39,P <0.05)than that of the NAWM regions far from NE lesions.However,no significant differences were found in CBV compared with NAWM regions close to the NE lesions.4)Vp and CBF had no significant differences between NE lesions,NAWM regions close to the lesions and NAWM regions far from NE lesions(P > 0.05).ConclusionOur results demonstrated the IVIM MRI can measure the diffusion and perfusion status of the lesions and NAWM in RRMS patients.Furthermore,it may be helpful for speculating the pathological changes of RRMS lesions and helps to injury classification and identification.Our result also demonstrates the DCE-MRI with the Patlak model can measure the microvascular permeability,perfusion characteristics and thehemodynamic abnormalities of the lesions and NAWM in patients with RRMS.