Optoacoustic Imaging: An Emerging Modality for the Gastrointestinal Tract  Nicolas Bézière, Vasilis Ntziachristos  Gastroenterology  Volume 141, Issue 6, Pages 1979-1985 (December 2011) DOI: 10.1053/j.gastro.2011.10.006 Copyright © 2011 AGA Institute Terms and Conditions

Figure 1 Tumor detection capacity of different imaging modalities in the GI tract. Autofluorescence imaging (AFI), confocal endomicroscopy (CEM), narrow band imaging (NBI) and two photon microscopy (TEM) rely on direct optical observation, whereas optoacoustic imaging (OI) relies on ultrasound detection, allowing for a much better penetration depth. Gastroenterology 2011 141, 1979-1985DOI: (10.1053/j.gastro.2011.10.006) Copyright © 2011 AGA Institute Terms and Conditions

Figure 2 Absorption spectra of blood (A); indocyanine green in plasma (green), gold nanorods (orange) and carbon nanotubes (black; B) in the near infra-red. Oxygenated (purple) and deoxygenated (blue) blood have markedly different absorption spectra, a feature that can be exploited to measure blood oxygenation using multispectral OI as suggested by the red dotted lines (A). Indocyanine green absorbs light in the near infra-red region of the spectra with a clear peak around 800 nm (green). Gold nanorods (orange) display a large absorption peak, whereas carbon nanotubes (black) absorb light evenly in the near infra-red wavelengths (B). Gastroenterology 2011 141, 1979-1985DOI: (10.1053/j.gastro.2011.10.006) Copyright © 2011 AGA Institute Terms and Conditions

Figure 3 Current performance of different modalities of OI. Structural image of a mouse ear microvasculature in vivo (A(i)) using optoacoustic tomography and oxygen saturation mapping of the same area (A(ii)).6 Large intestinal tract of a rat (B) imaged by endoscopic OI to locate blood vessels (BV) using a moving laser beam (LB) and showing a wall thickness of approximately 1 mm.7 Perfusion of a mouse kidney with indocyanide green followed by in vivo multispectral optoacoustic tomography at 800 nm (C(i)) and using image difference to highlight indocyanine green distribution (C(ii)).10 Mouse tumor images obtained by multispectral optoacoustic tomography using gold nanorods as a contrast agent; anatomic image acquired at 800 nm (D(i)), AuNP detected using multispectral acquisition overlaid on the anatomic image (D(ii)). Gastroenterology 2011 141, 1979-1985DOI: (10.1053/j.gastro.2011.10.006) Copyright © 2011 AGA Institute Terms and Conditions