Rapid, non-invasive measurement of gastric emptying rate using transcutaneous fluorescence spectroscopy.

Gastric emptying rate (GER) signifies the rate at which the stomach empties following ingestion of a meal and is relevant to a wide range of clinical conditions. GER also represents a rate limiting step in small intestinal absorption and so is widely assessed for research purposes. Despite the clinical and physiological importance of gastric emptying, methods used to measure GER possess a series of limitations (including being invasive, slow or unsuitable for certain patient populations). Here, we present a new technique based on transcutaneous (through-the-skin) fluorescence spectroscopy that is fast, non-invasive, and does not require the collection of samples or laboratory-based analysis. Thus, this approach has the potential to allow immediate reporting of clinical results. Using this new method, participants receive an oral dose of a fluorescent contrast agent and a wearable probe detects the uptake of the agent from the gut into the blood stream. Analysis of the resulting data then permits the calculation of GER. We compared our spectroscopic technique to the paracetamol absorption test (a clinically approved GER test) in a clinical study of 20 participants. Results demonstrated good agreement between the two approaches and, hence, the clear potential of transcutaneous fluorescence spectroscopy for clinical assessment of GER.