DTI Parameter Optimisation for Acquisition at 1.5T: SNR Analysis and Clinical Application

摘要

Background. Magnetic Resonance (MR) diffusiontensor imaging (DTI) is able to quantify in vivo tissuemicrostructure properties and to detect disease related pathologyof the central nervous system. Nevertheless, DTI is limited by lowspatial resolution associated with its low signal-to-noise-ratio(SNR).Aim. The aim is to select a DTI sequencefor brain clinical studies, optimizing SNR and resolution.Methods and Results. We applied 6 methods for SNRcomputation in 26 DTI sequences with different parameters using 4healthy volunteers (HV). We choosed two DTI sequences for theirhigh SNR, they differed by voxel size and b-value. Subsequently,the two selected sequences were acquired from 30 multiplesclerosis (MS) patients with different disability and lesion loadand 18 age matched HV. We observed high concordance between meandiffusivity (MD) and fractional anysotropy (FA), nonetheless theDTI sequence with smaller voxel size displayed a bettercorrelation with disease progression, despite a slightly lowerSNR. The reliability of corpus callosum (CC) fiber tracking withthe chosen DTI sequences was also tested.Conclusion. The sensitivity of DTI-derivedindices to MS-related tissue abnormalities indicates that theoptimized sequence may be a powerful tool in studies aimed atmonitoring the disease course and severity.