Noninvasive Characterization of Postprandial Intestinal Blood Flow Using Multispectral Optoacoustic Tomography

Detailed Summary

Inflammatory activities in the gastrointestinal tract are accompanied by an increase in blood flow in the intestinal wall layers of the respective organs. Also in chronic inflammatory bowel diseases, the release of vasoactive inflammatory mediators leads to vasodilation and consecutive increase of blood flow in the bowel wall. So far, these changes in blood flow can be detected by power Doppler sonography without being part of routine clinical diagnostics. Another promising option for non-invasive measurement of blood flow in the intestinal wall is Multispectral Optoacoustic Tomography (MSOT). Previous studies have shown that MSOT can be used to quantitatively measure hemoglobin in the bowel wall and thus provide information on blood flow and inflammatory activity in the intestines of patients with Crohn's disease. This is currently being further investigated in a pivotal study (Euphoria, H2020) and could lead to the possibility of non-invasive assessment of disease activity in inflammatory bowel disease (IBD) in the future. The regional blood flow in the intestinal wall and the distribution of gastrointestinal blood flow are also subject to strong postprandial changes. During absorption of food components, blood flow increases sequentially in the respective sections of the gastrointestinal tract, leading to postprandial hyperemia. Because postprandial hyperemia is particularly regulated locally by the presence of dietary components, there is a relationship between the sequential increase in blood flow in the intestinal wall and the peristaltic transport of chyme through the gastrointestinal tract. Postprandial hyperemia could also lead to an increase in the optoacoustic hemoglobin signal of the intestinal wall and thus have an impact on the assessment of inflammatory activity in IBD using MSOT. Additionally, MSOT allows the identification of non-absorbable exogenous chromophores, such as indocyanine green (ICG), which could allow co-localization of the chyme in the intestinal lumen after oral application of ICG. This pilot study investigates whether postprandial blood flow changes can be quantitatively measured using MSOT and whether these changes occur simultaneously with the gastrointestinal passage of the chyme as measured by the ICG signal in the intestinal lumen.

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