Non-invasive measurement of accelerated gastrointestinal transit in pediatric patients using Contrast-enhanced Multispectral optoacoustic tomography.

Functional intestinal disorders are common; however, current imaging modalities are limited. Contrast-enhanced Multispectral optoacoustic tomography (CE-MSOT) represents a novel, non-invasive, and radiation-free imaging technique that enables assessment of gastrointestinal transit time through the use of orally administered contrast agents. This could aid in symptom evaluation and diagnostic clarification in bowel disorders. A clinical pilot-study was conducted (Registry: ClinicalTrials.gov, TRN: NCT06617364, Registration date: 24 September 2024) involving 10 pediatric patients presenting with gastrointestinal complaints undergoing a lactose hydrogen breath test. CE-MSOT was performed following the oral administration of Indocyanine Green (ICG) as a contrast agent. In the terminal ileum and sigmoid colon multispectral optoacoustic tomography (MSOT) signals were spectrally unmixed to isolate ICG-specific signals. The appearance of ICG in these segments was used to estimate gastrointestinal transit time. ICG signals were detected in the terminal ileum as early as 13 min after oral administration (median: 80 min), and in the sigmoid colon as early as 41 min (median: 125 min).