Leukoaraiosis and pulse-wave encephalopathy: observations with phase-contrast MRI in mild cognitive impairment.

PURPOSE: To test the pathogenic hypothesis of a breakdown in the vital buffering of the arterial pulsations behind leukoaraiosis (LA) in mild cognitive impairment (MCI).
METHODS: Seventy-one elderly patients with MCI underwent a combined structural and dynamic MR examination (3D T1-weighted and fast-FLAIR T2-weighted sequences, phase contrast sequences). Arterial indices of pulsatility (IP) and composite indicators of the amplitude transfer function between cerebrospinal fluid and cerebral venous flow (Icsf/veins) were used to assess the large artery stiffness and the intracranial compliance respectively. Cerebral total arterial blood flow (tCBF), superficial and deep venous flow rates were also measured. Intracranial dynamic parameters and potential confounders including age, gender and vascular risk factors were compared between two groups respectively with and without significant LA.
RESULTS: The only dynamic changes on multivariate analyse were an IP increase, a lowering of deep venous outflow and Icsf/veins in patients with LA. There was a significant interaction between IP and Icsf/veins in the logistic regression: as compared with patients with low IP (suggestive of high large artery compliance) and high Icsf/veins (suggestive of high intracranial compliance), the adjusted odds ratios for the presence of LA were 9 (95% CI 1-64, P=0.02) in cases of both high IP and Icsf/veins, 10 (95% CI 1-64, P=0.02) in cases of both high IP and low Icsf/veins and 19 (95% CI 3-127, P=0.002) in cases of both low IP and Icsf/veins.
CONCLUSION: LA may reflect an arteriosclerotic and/or resistive pulse wave encephalopathy in MCI.