Contrast-enhanced multispectral optoacoustic tomography for the assessment of the gastrointestinal transit in patients with cystic fibrosis

Cystic fibrosis (CF) affects the gastrointestinal tract, but assessing gastrointestinal transit usually requires invasive procedures or exposure to ionizing radiation. Contrast-enhanced multispectral optoacoustic tomography (CE-MSOT) offers a novel, non-invasive, and radiation-free approach to assess gastrointestinal function by orally administered dyes. In this clinical pilot-study five patients with cystic fibrosis and four healthy volunteers received CE-MSOT before and 6-times hourly after a standardized breakfast with Indocyanin green (ICG) as dye. The gastric antrum, terminal ileum and sigmoid colon were recorded and MSOT signals spectrally unmixed to detect ICG signals to determine the transit time. ICG excretion was confirmed by fluorescence imaging of stool samples. MSOT ICG signals were detected earlier in the terminal ileum of CF patients, reaching a maximum after 120 min (p = 0.0079), compared to 240 min (p = 0.0286) in healthy controls after ICG intake (p = 0.0159). In CF patients, ICG signal was further detected in the sigmoid colon from 240 min onwards (p = 0.0079 after 300 min). But, no significant changes in the ICG signal were observed in the sigmoid colon of controls. Furthermore, signals of ICG were verified in 12 of 19 stool samples by fluorescence imaging. In this study, we demonstrated the potential of CE-MSOT for functional imaging of the intestine in CF patients and revealed faster intestinal transit in CF patients compared to healthy controls.