N.V. Anisimov1, L.L. Gervits2

1 Lomonosov Moscow State University (Moscow, Russia)

2 A.N. Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences (Moscow, Russia)

1 anisimovnv@mail.ru, 2 gervits@ineos.ac.ru

This study demonstrates the feasibility of assessing gastrointestinal (GI) motor functions using fluorine-19 magnetic resonance imaging (19F MRI) with ingestible capsules commonly used for oral drug delivery. These capsules feature shells designed to dissolve in either the stomach or the small intestine.

In our experiments, the capsules were filled with liquid, biologically inert perfluorocarbons (PFCs), which served as a contrast agent. By acquiring the 19F MRI signal at short, regular intervals, we were able to track the capsule's location in real time and monitor the dynamics of the contrast agent's concentration. The signal decay rate is linked to the intensity of biochemical and mechanical processes in the GI tract responsible for digesting food. This intensity may, in turn, differ between healthy and pathological states.

The experiments were carried out on a 0.5-T MR scanner Bruker Tomikon S50. The protocol involved a subject swallowing a capsule filled with perfluorodecalin. 19F MRI scans were then performed using a 3D GRE sequence (TR/TE=50/3.5 ms) with a resolution of 5×5×10 mm³ in the coronal plane every 2 minutes. Depending on the ability to distinguish the capsule signal from the background noise, the total scanning time varied from 40 to 80 minutes. A subsequent single 1H MRI scan was acquired to coregister the 19F signal locations with anatomical structures.

The movement and disintegration dynamics of the enteric-soluble capsule were highly variable. As gastric fullness was suspected to be a primary cause, follow-up experiments with gastro-soluble capsules were conducted under two conditions: fasting and postprandial. The resulting data were used to plot the temporal changes in the MRI signal under these different scenarios.

Our findings indicate that the intensity of capsule shell disintegration and subsequent content distribution depends on the subject's posture and the time since their last meal. Specifically, the intensity was reduced when the subject was in a supine position and was higher under fasting conditions compared to the postprandial state. We hypothesize that certain features of the signal dynamics may be attributed to hunger motility. Furthermore, we note the potential of using other PFCs, such as perfluorotributylamine, which provides a stronger 19F MRI signal, as future tracers.

Anisimov N.V., Gervits L.L. Fluorine-19 magnetic resonance imaging of the gastrointestinal tract. Technologies of Living Systems. 2026. V. 23. № 2. Р. 37-45. DOI: https://doi.org/10.18127/j20700997-202602-03 (In Russian).

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