Magnetic Resonance Imaging of Gastric Motility in Conscious Rats

Area of Science:

• Gastrointestinal physiology
• Medical imaging
• Animal models

Background:

• Gastrointestinal (GI) magnetic resonance imaging (MRI) is valuable for assessing GI motility.
• Anesthesia in animal studies confounds GI physiology, limiting translational research.
• A need exists for GI MRI protocols in conscious animals.

Purpose of the Study:

• To develop and validate a method for performing GI MRI in awake rats.
• To compare GI motor functions in awake versus anesthetized rats.

Main Methods:

• Rats were acclimated to remain still and awake during MRI.
• 14 Sprague-Dawley rats underwent GI MRI in both awake and anesthetized states.
• A contrast-enhanced meal was used to visualize GI transit.

Main Results:

• Awake rats exhibited significantly faster gastric emptying (23.7% in 48 min) and stronger peristaltic contractions (velocity 0.72 mm/s, amplitude 40.7%, frequency 5.1 cycles/min).
• Anesthesia reduced gastric emptying by half, primarily by decreasing peristaltic contraction amplitude.
• Awake rats showed quicker intestinal filling and more occlusive propulsive contractions.

Conclusions:

• GI MRI is feasible and effective in awake rats.
• Conscious rats demonstrate superior GI motor function compared to anesthetized counterparts.
• This protocol enhances preclinical GI research by providing more accurate physiological data.