3D transcranial ultrasound localization microscopy for discrimination between ischemic and hemorrhagic stroke in early phase

Abstract

Early diagnosis is a critical part of the emergency care of cerebral hemorrhages and ischemia. A rapid and accurate diagnosis of strokes reduces the delays to appropriate treatments and a better functional recovery. Currently, CTscan and MRI are the gold standards with constraints of accessibility, availability, and possibly some contraindications. The development of Ultrasound Localization Microscopy (ULM) has enabled new perspectives to conventional transcranial ultrasound imaging with increased sensitivity, penetration depth, and resolution. The possibility of volumetric imaging has increased the field-of-view and provided a more precise description of the microvascularisation. In this study, rats (n = 9) were subjected to thromboembolic ischemic stroke or intracerebral hemorrhages prior to volumetric ULM at the early phases after onsets. Although the volumetric ULM performed in the early phase of ischemic stroke revealed a large hypoperfused area in the cortical area of the occluded artery, it showed a more diffused hypoperfusion in the hemorrhagic model. Respective computations of a Microvascular Diffusion Index highlighted different patterns of perfusion loss during the first 24 h of these two strokes’ subtypes. Our study provides the first proof that this methodology should allow early discrimination between ischemic and hemorrhagic stroke with a potential toward diagnosis and monitoring in clinic.

The development of a 1.25 MHz 1024-channel sparse array for human transcranial imaging: in vitro characterization

“…Planewave sequences can be used for ultrafast imaging at very high frame-rates, which are useful to a number of imaging modalities, including power Doppler [22], super-resolution [21], elastography [64], and more. These modalities may be used for diagnosis of stroke [65], aneurysm [6], and tumor identification [64]. The significant advantage of this transducer in these imaging modalities is its large FOV, which would enable a single probe placement to cover a large portion of the brain.…”

3D Acoustic Wave Sparsely Activated Localization Microscopy With Phase Change Contrast Agents

“…The activation of PCCAs could be broad or selective, with the latter making vascular connections visible without further processing. Three-dimensional ULM has already been shown capable of discriminating between ischemic and hemorrhagic stroke 26 . Three-dimensional AWSALM may add additional value by being able to detect vascular connectivity, for example, collateral vasculature that serves as a natural bypass in response to reduced or blocked blood flow, 32 and by being able to follow the flow from the source to the peripheral vasculature.…”

Quantitative pulsatility measurements using 3D dynamic ultrasound localization microscopy

“…In brain studies in particular, 2D ULM was shown to retrieve blood flow parameters such as cerebral vascularity, mean blood velocity and vessel tortuosity in an Alzheimer's mouse model (Lowerison et al 2022), and systolic and diastolic velocities in the human brain (Demené et al 2021). The method was also tested to characterize strokes in the rodent brain, in both 2D (Hingot et al 2020) and 3D (Chavignon et al 2022b). In silico, it was shown that microbubble tracks in ULM could even contain more information such as the pulsatility (Wiersma et al 2022).…”