Functional optoacoustic human angiography with handheld video rate three dimensional scanner

Abstract

Optoacoustic imaging provides a unique combination of high optical contrast and excellent spatial resolution, making it ideal for simultaneous imaging of tissue anatomy as well as functional and molecular contrast in deep optically opaque tissues. We report on development of a portable clinical system for three-dimensional optoacoustic visualization of deep human tissues at video rate. Studies in human volunteers have demonstrated powerful performance in delivering high resolution volumetric multispectral optoacoustic tomography (vMSOT) images of tissue morphology and function, such as blood oxygenation parameters, in real time. Whilst most imaging modalities currently in clinical use are not able to deliver volumetric data with comparable time resolution, the presented imaging approach holds promise to attain new diagnostic and treatment monitoring value for multiple indications, such as cardiovascular and peripheral vascular disease, disorders related to the lymphatic system, breast lesions, arthritis and inflammation.

Keywords: Cardiovascular diagnostics; Functional and molecular imaging; Optoacoustic imaging.

Fig. 1

Layout and color photograph of the clinical hand-held vMSOT probe for high resolution 3D (volumetric) imaging at video rate.

Fig. 2

Video-rate optoacoustic tracking of deep tissue vasculature in vivo, acquired by translating the probe over forearm of a healthy volunteer. (a) Single frame volumetric (maximum intensity projection along the depth direction) images acquired at distinctive time points. (b) A combined volumetric image of a larger region color-coded for depth and the corresponding imaged region (c).

Fig. 3

Multispectral tomographic reconstructions of the wrist region. (a) Volumetric (maximum intensity projection along the depth direction) images acquired at 5 different wavelengths in the near-infrared. Two main types of vessels (arteries and veins) can be readily identified by their spectral behavior. (b) Map of blood oxygen saturation, as calculated from images acquired at the different wavelengths. (c) Extinction (absorption) spectra of major tissue chromophores in arbitrary units. The curves for hemoglobin are shown for 100% oxygenation (continuous red line), 75% oxygenation (dashed red line), 50% oxygenation (dashed black line), 25% oxygenation (dashed blue line) and 0% oxygenation (continuous blue line). (d) Color photograph of the imaged region.

Fig. 4

Tomographic reconstructions of the vasculature in human finger in the region as indicated in the photograph on the left. The snapshots are shown for seven consecutive seconds around the time point when the rubber band, blocking the blood flow, was removed from the finger (ca. 42 s after the start of image acquisition).