The Pulseq-CEST Library: definition of preparations and simulations, example data, and example evaluations.

Area of Science:

• Magnetic Resonance Imaging
• Biomedical Engineering
• Medical Physics

Background:

• Chemical Exchange Saturation Transfer (CEST) MRI is widely used but lacks standardization due to complex parameter dependencies.
• Radiofrequency (RF) pulses, gradients, and apparent diffusion coefficient (ADC) significantly influence CEST imaging outcomes.
• A need exists for a common platform to ensure reproducibility and facilitate advancements in CEST MRI.

Purpose of the Study:

• To introduce the Pulseq-CEST Library, a standardized repository for CEST preparation and simulation definitions.
• To provide a common basis for reproducible CEST MRI research, rapid prototyping, and generation of in silico training data for deep learning.
• To address the lack of standardization in CEST MRI acquisition and analysis.

Main Methods:

• The Pulseq-CEST Library utilizes Bloch-McConnell equations to model CEST experiments under various conditions.
• It integrates CEST preparation sequences, Bloch-McConnell parameter sets, simulations, and evaluation scripts.
• The framework allows for systematic testing by holding certain parameters constant while varying others.

Main Results:

• Validation was performed by comparing amide proton transfer weighted (APTw) and water shift and B1 (WASABI) protocols using phantom and simulated data.
• Real and simulated data demonstrated agreement in spectral shapes and local peak characteristics.
• The library successfully supported assessment of new protocols and sample data.

Conclusions:

• The Pulseq-CEST Library offers a flexible solution for standardizing and prototyping CEST MRI sequences.
• It fosters collaborative development and accelerates the invention and dissemination of novel saturation transfer imaging methods.
• The library's open-source nature and expandability support future advancements in CEST, rNOE, and MTC techniques.