Multispectral Optoacoustic Tomography for the Assessment of Liver Fibrosis and Gastrointestinal Transit in Patients With Cystic Fibrosis

Cystic fibrosis (CF) is the most common hereditary disease in Central Europe, with an incidence of approximately 3,300 to 4,800 new cases. The disease follows an autosomal recessive pattern of inheritance, the cause being a mutation in the cystic fibrosis transmembrane conductance regulator gene (CFTR). In the liver, fibrotic remodeling can lead to liver cirrhosis in the long term. Early detection of CF hepatopathy is essential to therapeutically slow down the progression of fibrotic remodeling mechanisms. Over the past decade, measurements of liver stiffness using Acoustic Radiation Force Impulse Imaging (ARFI) have proven to be a valid tool for measuring fibrotic tissue remodeling in CF in adults and children. Furthermore, in the gastrointestinal tract, serious consequences result from the absence of the CFTR channel. Newborns suffering from CF have a significantly increased risk for the occurrence of meconium ileus and also with advancing age there are symptoms ranging from chronic constipation to DIOS (Distal Intestinal Obstruction Syndrome), due to a reduction of intestinal motility.

By means of new imaging methods, such as multispectral optoacoustic tomography, it is possible to examine not only the body's own substances but also substances foreign to the body. With Multispectral Optoacoustic Imaging (MSOT), similar to conventional sonography, a transducer is placed on the skin and instead of sound, energy is applied to the tissue by means of light flashes. This leads to a constant alternation of minimal expansions and contractions (thermoelastic expansion) of individual tissue components or molecules. Previous studies have shown that quantitative determination of hemoglobin can provide information on blood flow and inflammatory activity in the intestines of adult patients with Crohn's disease. Also, fibrotic changes in the liver can probably be detected with this method, similar to that in muscle tissue. Furthermore, we have recently shown that orally ingested Indocyanine green (ICG) can be detected in the small intestine and thus conclusions can be drawn about gastrointestinal passage, without the use of ionizing radiation. In this study, the degree of liver fibrosis will now be investigated in adult patients with cystic fibrosis using MSOT. In addition, gastrointestinal passage will be studied non-invasively to investigate another affection of the gastrointestinal system.