Spiral volumetric optoacoustic tomography for imaging whole-body biodynamics in small animals

The authors describe spiral volumetric optoacoustic tomography for the visualization of contrast agent perfusion and biodistribution in mice, featuring excellent scalability to achieve spatial resolution down to 90 mu m or whole-body scans in <2 s. Fast tracking of biological dynamics across multiple murine organs using the currently commercially available whole-body preclinical imaging systems is hindered by their limited contrast, sensitivity and spatial or temporal resolution. Spiral volumetric optoacoustic tomography (SVOT) provides optical contrast, with an unprecedented level of spatial and temporal resolution, by rapidly scanning a mouse using spherical arrays, thus overcoming the current limitations in whole-body imaging. The method enables the visualization of deep-seated structures in living mammalian tissues in the near-infrared spectral window, while further providing unrivalled image quality and rich spectroscopic optical contrast. Here, we describe the detailed procedures for SVOT imaging of mice and provide specific details on how to implement a SVOT system, including component selection, system arrangement and alignment, as well as the image processing methods. The step-by-step guide for the rapid panoramic (360 degrees) head-to-tail whole-body imaging of a mouse includes the rapid visualization of contrast agent perfusion and biodistribution. The isotropic spatial resolution possible with SVOT can reach 90 mu m in 3D, while alternative steps enable whole-body scans in less than 2 s, unattainable with other preclinical imaging modalities. The method further allows the real-time (100 frames per second) imaging of biodynamics at the whole-organ level. The multiscale imaging capacity provided by SVOT can be used for visualizing rapid biodynamics, monitoring responses to treatments and stimuli, tracking perfusion, and quantifying total body accumulation and clearance dynamics of molecular agents and drugs. Depending on the imaging procedure, the protocol requires 1-2 h to complete by users trained in animal handling and biomedical imaging.

Automated summary

The authors propose spiral volumetric optoacoustic tomography (SVOT) for visualizing contrast agent perfusion and biodistribution in mice. The method overcomes the limitations of current whole-body imaging by providing optical contrast and unprecedented spatial and temporal resolution. SVOT allows visualization of deep-seated structures in living tissues and real-time imaging of biodynamics at the whole-organ level.