Magnetic Resonance Imaging of Gastric Motility in Conscious Rats

Area of Science:

• Gastroenterology
• Medical Imaging
• Physiology

Background:

• Gastrointestinal (GI) magnetic resonance imaging (MRI) allows simultaneous assessment of gastric peristalsis, emptying, and intestinal transit.
• Anesthesia in animal GI MRI confounds physiological interpretation and translation to human studies.
• Establishing GI MRI in conscious animals is crucial for accurate preclinical research.

Purpose of the Study:

• To establish a protocol for gastrointestinal (GI) magnetic resonance imaging (MRI) in conscious rats.
• To characterize and compare GI motor functions in awake versus anesthetized rats.

Main Methods:

• Fourteen Sprague-Dawley rats were trained for awake, minimally stressed MRI acquisition.
• GI MRI was performed in the same rats under both awake and anesthetized conditions after consuming a contrast-enhanced meal.

Main Results:

• Awake rats exhibited stable physiology during MRI, with 23.7% gastric emptying at 48 min and robust peristaltic contractions.
• Anesthesia significantly reduced gastric emptying by approximately 50%, primarily due to decreased peristaltic amplitude.
• Awake rats demonstrated faster small intestinal filling and stronger motility compared to anesthetized rats.

Conclusions:

• Gastrointestinal (GI) MRI is feasible in awake rats, providing reliable physiological data.
• Significant differences in gastric and intestinal motility exist between awake and anesthetized states.
• This awake GI MRI protocol offers a novel framework for preclinical GI physiology and pathophysiology studies.