Ultrafast high frequency ultrasound Doppler imaging and its biomedical applications

Abstract

Cerebrovascular disorders are associated with Alzheimer’s disease (AD). Preclinical animal study is necessary for understanding AD pathogenesis and determining its optimal diagnosis and treatment strategies. Conventionally, the cerebral vasculature’s structure is analyzed through histological staining. However, functional analysis of the cerebral vasculature requires an in vivo approach to visualize the blood flow in small animal brains. This paper proposes high-frequency micro-Doppler imaging (HFμDI) technology for mapping mouse cerebral vasculature. Using a 40-MHz transducer enabled in vivo visualization of the mouse brain up to 3 mm in depth; furthermore, a minimal vessel diameter of 48 μm could be determined without using microbubbles. Animal experiments determined that the cortical and hippocampal vessel density in young (4-month-old) wild-type mice was similar to that in middle-aged (11-month-old) wild-type mice. However, compared with the vessel density in middle-aged wild-type mice, that in middle-aged mice with AD was significantly lower, particularly in the hippocampus. In vivo observation of cerebral vasculature demonstrated the effectiveness of HFμDI for the preclinical study of AD and as a potential tool for AD diagnosis.