Current and Emerging Clinical Applications of Multispectral Optoacoustic Tomography (MSOT) in Oncology

Abstract

Accurate detection and characterization of cancers are key for providing timely intervention and effective treatments. Current imaging technologies are particularly limited when it comes to detecting very small tumors in vivo, i.e., very early cancers or metastases, differentiating viable tumor from surrounding dead tumor tissue, and evaluating tumor metabolism within tissue. Optoacoustic imaging offers potential solutions to these imaging problems because of its ability to image optical absorption properties of both intrinsic tissue chromophores and exogenous contrast agents without the involvement of ionizing radiation. Optoacoustic imaging uses pulsed laser to induce localized thermoelastic expansion that generates acoustic waves detectable by an ultrasound transducer. To date, multispectral optoacoustic tomography (MSOT) has primarily been used in preclinical research; however, its use in translational and clinical research is expanding. This review focuses on current and emerging applications of optoacoustic imaging for molecular imaging of cancer using both exogenous and endogenous contrast agents and sheds light on potential future clinical applications. Clin Cancer Res; 22(14); 3432-9. ©2016 AACR.

Figure 1

Single wavelength images were each captured using MSOT to form a background image. The representative images were taken at 900 nm. The image slices shown represents the region of the liver (A) and kidney (B). The following structures were identified:spinal cord (SC); aorta (A); vena cava (VC); vena porta (VP); liver (L); stomach (ST); kidney (K); spleen (SP).

Figure 2

Oxy- and deoxy-hemoglobin were detected using MSOT. Oxy- and deoxyhemoglobin were visualized within a human wrist using a pre-clinical MSOT instrument. The red color bar represents oxyhemoglobin and the blue color bar represents deoxyhemoglobin. The gray scale image was provided using a 900 nm single wavelength.

Figure 3

Accumulation of a pH responsive ligand-targeted probe within an orthotopic pancreatic tumor. The orthogonal image demonstrates 3D accumulation of V7-750 within the mouse in the xyz-plane. The rainbow color bar represents intensity of the V7-750 probe. Adapted from Kimbrough et al. (1).