A rapid approach for quantitative magnetization transfer imaging in thigh muscles using the pulsed saturation method

Area of Science:

• Medical Imaging
• Biophysics
• Musculoskeletal Imaging

Background:

• Quantitative magnetization transfer (qMT) imaging of skeletal muscle faces challenges including fat content, low signal-to-noise ratios (SNRs), and motion artifacts.
• These factors can introduce bias and errors in parameter fitting, affecting diagnostic accuracy.

Purpose of the Study:

• To systematically investigate technical factors confounding skeletal muscle qMT imaging.
• To propose and validate solutions to improve the accuracy and reliability of qMT parameter estimation in skeletal muscle.

Main Methods:

• Numerical simulations were used to assess the impact of fat components and identify optimal sampling points for a rapid two-parameter model.
• Fat-signal suppression (water-selective excitation) was recommended to mitigate fat contamination.
• A rapid two-parameter model was adapted and evaluated against a five-parameter model in healthy controls and polymyositis patients.

Main Results:

• Numerical simulations confirmed that fat components significantly underestimate the pool size ratio (F).
• The rapid two-parameter model demonstrated improved accuracy and precision for estimating F, consistent with simulations.
• Experimental qMT data fitting validated the model's performance in clinical populations.

Conclusions:

• Fat-signal suppression is crucial for accurate qMT imaging in skeletal muscle.
• The rapid two-parameter modeling approach is effective for skeletal muscle qMT, reducing scan time and allowing for signal averaging.
• This optimized approach enhances the reliability of qMT imaging for skeletal muscle research and clinical applications.