Photophysical structured illumination velocimetry based on the long-lasting emission response of luminescent nanoparticles

Abstract:

In vivo imaging of cerebral hemodynamics in three dimensions is vital for advancing brain research. Existing techniques—such as laser Doppler velocimetry, blood-oxygenation level-dependent functional magnetic resonance imaging (BOLD fMRI), and two-photon laser scanning microscopy (TPLSM)—have yielded important insights but are significantly limited in terms of imaging depth and/or speed. Achieving rapid, volumetric blood-flow velocity imaging at meaningful depths remains a major challenge.

To address this, we recently introduced a concept: Photophysical Structured Illumination Velocimetry (PP-SIV). This method leverages luminescent nanoparticles with slow emission kinetics—specifically, lanthanide-doped nanoparticles (LNPs)—to extract flow velocity fields from a single snapshot of tracer emission patterns, using a predefined excitation pattern as reference. By eliminating the need for time-consuming excitation scanning, PP-SIV offers the potential for fast, volumetric flow imaging deep within biological tissues.

In this lecture, I will talk about the PP-SIV concept, highlight its advantages over existing techniques, and discuss potential experimental implementations, as well as its constraints and limitations.