No abstract

A major difficulty arising from whole-body optoacoustic imaging is the long acquisition times associated with recording signals from multiple spatial projections. The acquired signals are also generally weak and the signal-to-noise-ratio is low, problems often solved by signal averaging, which complicates acquisition and increases acquisition times to an extent that makes many in vivo applications challenging or even impossible. Herein we present a fast acquisition multispectral optoacoustic tomography (MSOT) scanner for whole-body visualization of molecular markers in small animals. Multi-wavelength illumination offers the possibility to resolve exogenously administered fluorescent probes, biomarkers, and other intrinsic and exogenous chromophores. The system performance is determined in phantom experiments involving molecular probes and validated by imaging of small animals of various scales.

The characterization of pharmacokinetic and biodistribution profiles is an essential step in the development process of new candidate drugs or imaging agents. Simultaneously, the assessment of organ function related to the uptake and clearance of drugs is of great importance. To this end, we demonstrate an imaging platform capable of high-rate characterization of the dynamics of fluorescent agents in multiple organs using multispectral optoacoustic tomography (MSOT). A spatial resolution of approximately 150 µm through mouse cross-sections allowed us to image blood vessels, the kidneys, the liver and the gall bladder. In particular, MSOT was employed to characterize the removal of indocyanine green from the systemic circulation and its time-resolved uptake in the liver and gallbladder. Furthermore, it was possible to track the uptake of a carboxylate dye in separate regions of the kidneys. The results demonstrate the acquisition of agent concentration metrics at rates of 10 samples per second at a single wavelength and 17 s per multispectral sample with 10 signal averages at each of 5 wavelengths. Overall, such imaging performance introduces previously undocumented capabilities of fast, high resolution in vivo imaging of the fate of optical agents for drug discovery and basic biological research.

Macroscopic visualization of functional and molecular features of cardiovascular disease is emerging as an important tool in basic research and clinical translation of new diagnostic and therapeutic strategies. We showcase the application of Multispectral Optoacoustic Tomography (MSOT) techniques to noninvasively image different aspects of the mouse cardiovascular system macroscopically in real-time and in vivo, an unprecedented ability compared to optical or optoacoustic (photoacoustic) imaging approaches documented so far. In particular, we demonstrate imaging of the carotid arteries, the aorta and the cardiac wall. We further demonstrate the ability to dynamically visualize circulating gold nanorods that can be used to enhance contrast and be extended to molecular imaging applications. We discuss the potential of this imaging ability in cardiovascular disease (CVD) research and clinical applications.