Sensitivity and resolution of two-dimensional NMR diffusion-relaxation measurements

Area of Science:

• Nuclear Magnetic Resonance (NMR) Spectroscopy
• Fluid Characterization
• Diffusion-Relaxation Analysis

Background:

• 2D NMR diffusion-relaxation measurements are crucial for fluid typing.
• Understanding the interplay between diffusion coefficients and relaxation times is key.
• Previous studies have explored various NMR encoding strategies.

Purpose of the Study:

• To analyze the performance of 2D NMR diffusion-relaxation measurements for fluid typing.
• To delineate the determinable diffusion-relaxation plane based on gradient strength and homogeneity.
• To compare single/double echo encoding with stimulated echo diffusion encoding.

Main Methods:

• Analysis of 2D NMR diffusion-relaxation measurements.
• Comparison of single echo, double echo, and stimulated echo diffusion encoding.
• Delineation of diffusion-relaxation plane regions based on gradient parameters.
• Investigation of diffusion coefficient determination with diffusion editing.

Main Results:

• Diffusion coefficient determination requires T2 > T2,cutoff (T2,cutoff∝g(-2/3)D(-1/3)).
• Optimal stimulated echo encoding times depend on T1/T2 ratios, not gradient strength or diffusion coefficients.
• Hahn echo encoding is superior for high gradients; stimulated echo is superior for weak gradients and high T1/T2 ratios.
• Non-uniform gradients affect diffusion distribution determination for fluids with similar T2.

Conclusions:

• The choice of NMR diffusion encoding method significantly impacts fluid typing accuracy.
• Gradient strength, homogeneity, and fluid relaxation properties are critical parameters.
• Understanding these dependencies allows for optimized experimental design in fluid characterization.