Contrast Agent‐Free 3D Renal Ultrafast Doppler Imaging Reveals Vascular Dysfunction in Acute and Diabetic Kidney Diseases

Abstract

To combat the irreversible decline in renal function associated with kidney disease, it is essential to establish non‐invasive biomarkers for assessing renal microcirculation. However, the limited resolution and/or vascular sensitivity of existing diagnostic imaging techniques hinders the visualization of complex cortical vessels. Here, a 3D renal ultrafast Doppler (UFD) imaging system that uses a high ultrasound frequency (18 MHz) and ultrahigh frame rate (1 KHz per slice) to scan the entire volume of a rat's kidney in vivo is demonstrated. The system, which can visualize the full 3D renal vascular branching pyramid at a resolution of 167 µm without any contrast agent, is used to chronically and noninvasively monitor kidneys with acute kidney injury (AKI, 3 days) and diabetic kidney disease (DKD, 8 weeks). Multiparametric UFD analyses (e.g., vessel volume occupancy (VVO), fractional moving blood volume (FMBV), vessel number density (VND), and vessel tortuosity (VT)) describe rapid vascular rarefaction from AKI and long‐term vascular degeneration from DKD, while the renal pathogeneses are validated by in vitro blood serum testing and stained histopathology. This work demonstrates the potential of 3D renal UFD to offer valuable insights into assessing kidney perfusion levels for future research in diabetes and kidney transplantation.

Video-rate endocavity photoacoustic/harmonic ultrasound imaging with miniaturized light delivery

“… 21 – 23 As a hybrid optical and acoustical imaging modality, PA imaging provides unique photochemical contrast capabilities at previously uncharted depths within biological tissue, 24 – 29 surpassing the capabilities of other optical imaging methods. 30 – 37 It mirrors the US imaging process 38 – 42 but utilizes pulsed laser excitation to induce the PA effect in tissue chromophores (e.g., hemoglobin, melanin, lipid, and collagen). 43 – 46 The resultant thermal expansion generates an acoustic signal, 47 – 49 which can be reconstructed into cross-sectional distributions of chromophores akin to US B-mode images.…”