Ingestible roasted barley for contrast-enhanced photoacoustic imaging in animal and human subjects

Abstract

Photoacoustic computed tomography (PACT) is an emerging imaging modality. While many contrast agents have been developed for PACT, these typically cannot immediately be used in humans due to the lengthy regulatory process. We screened two hundred types of ingestible foodstuff samples for photoacoustic contrast with 1064 nm pulse laser excitation, and identified roasted barley as a promising candidate. Twenty brands of roasted barley were further screened to identify the one with the strongest contrast, presumably based on complex chemical modifications incurred during the roasting process. Individual roasted barley particles could be detected through 3.5 cm of chicken-breast tissue and through the whole hand of healthy human volunteers. With PACT, but not ultrasound imaging, a single grain of roasted barley was detected in a field of hundreds of non-roasted particles. Upon oral administration, roasted barley enabled imaging of the gut and peristalsis in mice. Prepared roasted barley tea could be detected through 2.5 cm chicken breast tissue. When barley tea was administered to humans, photoacoustic imaging visualized swallowing dynamics in healthy volunteers. Thus, roasted barley represents an edible foodstuff that should be considered for photoacoustic contrast imaging of swallowing and gut processes, with immediate potential for clinical translation.

Trans-illumination intestine projection imaging of intestinal motility in mice

“…The results indicate that TIP can visualize the 0.5-mm-inner-diameter tube at up to 8 mm depth. This imaging depth covers the majority of intestines underneath the abdomen wall 13 . The mouse intestine has an average diameter of 4 mm 14 in the resting condition, but the diameter dramatically decreases during contraction.…”

A human photoacoustic imaging reporter gene using the clinical dye indocyanine green

“…Our study extends this work, establishing Oatp1b3 as a multimodality reporter for numerous clinically-relevant modalities such as FLI (Figure 3), and now PAI (Figure 4), and also introduces potential for Oatp1b3 reporter gene imaging on a clinical 3-Tesla MR scanner (Supplementary Figure 3). Extending this system to PAI is important as PAI uniquely offers a non-ionizing and cost-effective method to detect deeply-located engineered cell populations with sensitivity, specificity, and high resolution at sites that are not hindered by optically-scattering materials, though more penetrative PA systems are continuously being developed for such sites 43,44,45,46 . It is important to caution, however, that ICG is endogenously taken up and cleared by the liver and kidneys.…”

Ingestible Contrast Agents for Gastrointestinal Imaging

“…In addition, pineapple juice marked with gadolinium suppresses the signal intensity of the stomach or duodenum . A recent screen of 200 foodstuffs identified roasted barley as a promising photoacoustic contrast agent in mice and humans . Another imaging example is 19 F magnetic resonance imaging, and highly selective images of the GI tract can be generated by using perfluorononane on a mouse model.…”

“…[121] Ar ecent screen of 200 foodstuffs identified roasted barley as ap romisingp hotoacousticc ontrasta gent in mice and humans. [122] Another imaging example is 19 Fm agnetic resonance imaging, and highly selectiveimages of the GI tract can be generated by using perfluorononane on am ouse model. In the study,e ach mouse was orallyg avaged 0.3 mL of perfluorononanea fter fasting for 1h.S ubsequently,a 19 Fr esonator was used for MRI with prone position.…”

“…Therefore, InFroMs represent a novel nanoplatform that can be used for multimodal imaging of the intestine . Beyond that, other novel imaging strategies are adding new possibilities to the field of theranostics and molecular imaging …”