A new MR-compatible loading device to study in vivo muscle damage development in rats due to compressive loading

Area of Science:

• Biomedical Engineering
• Tissue Mechanics
• Medical Imaging

Background:

• Pressure ulcers are a significant clinical challenge.
• Understanding the aetiology of pressure ulcers requires studying muscle tissue response to mechanical loading.
• Non-invasive methods for evaluating tissue damage are needed.

Purpose of the Study:

• To develop an MR-compatible device for studying the effects of mechanical loading on muscle tissue.
• To investigate the aetiology of pressure ulcers by evaluating muscle damage under controlled loading conditions.
• To correlate MRI findings with histological outcomes.

Main Methods:

• Development of an MR-compatible loading device for applying controlled pressure to rat tibialis anterior muscle.
• Utilizing T2-weighted Magnetic Resonance Imaging (MRI) for non-invasive tissue evaluation during and after loading.
• Employing two loading protocols: high pressure (150 kPa) for 2 hours and low pressure (50 kPa) for 4 hours.
• Histological examination of muscle tissue post-MRI to assess damage and inflammatory response.

Main Results:

• High-pressure loading (150 kPa, 2h) resulted in increased MRI signal intensity post-load, indicating tissue damage.
• Sustained signal intensity increase observed 20 hours after high-pressure loading.
• Histological analysis confirmed severe muscle necrosis and inflammatory response following high-pressure loading.
• Low-pressure loading (50 kPa, 4h) did not produce observable changes in MRI signal intensity.

Conclusions:

• The developed MR-compatible loading device enables high-quality, non-invasive assessment of muscle tissue response to mechanical stress.
• Higher pressure, even for shorter durations, is a significant factor in inducing muscle necrosis and contributes to pressure ulcer development.
• This methodology facilitates further research into the multifactorial aetiology of pressure ulcers.