Correlation between Leukoaraiosis and natural brain tissue velocity: A pilot study using Ultrasound and MRI

Leukoaraiosis (LA) refers to lesions and rarefaction of the cerebral White Matter (WM) and is frequently seen in aged individuals. Although the mechanism of LA remains unknown, a decrease in cerebral perfusion is suspected to be linked to LA. LA can be seen in individuals without any clinical abnormality, however new findings suggest that LA may be clinically relevant [1,2]. Patients with LA have a decreased prognosis in term of death, stroke and myocardial infarction occurrences. The aim of our work was to study the relationship between LA and the natural brain tissue velocity due to pulsed cerebral perfusion. Brain velocities were measured with an analog of the Tissue Pulsatility Imaging (TPI) method described by Kucewicz [3,4], which has been already used in our group for depressed patients [5]. Thirteen voluntary healthy women aged between 60 and 85 were enrolled in this cross-sectional study. Transcranial acquisitions were performed with a 2 MHz phased-array probe through the right temporal bone window and off-line estimations of velocity were performed by correlation on the RF signals. MRI examinations were performed on a 1.5T GE system using dedicated software (MRIcro) to obtain a volumetric analysis. The primary endpoints of the study were the maximum brain tissue velocity (TPImax), the absolute MRI volume of WM hyperintensity (VAbs) and the relative volume (VRel) on the right hemisphere. The Spearman correlation coefficient was used for statistical analysis. Our main finding is that TPImax decreases significantly when the severity of LA increases. Significant negative correlation between TPImax and VRel (ρ= -0.81, p <; 0.01) is observed despite the small size of our recruitment. LA and other neurodegenerative pathologies being considered to have a strong link with brain vascular defects, the ultrasonic TPI method appears to be valuable and promising.