Precision limits of tissue microstructure characterization by Magnetic Resonance Imaging

TL;DR

This paper derives the fundamental precision limits for microstructure characterization in tissues using MRI, showing that optimal control of MRI sequences can significantly improve diagnostic capabilities and reduce measurement time.

Contribution

It introduces a quantum information theory-based framework to determine the ultimate precision limits of MRI microstructure probing and suggests optimal control strategies to reach these limits.

Findings

Optimal MRI pulse sequences can attain the ultimate precision limits.

Measurement time and number can be drastically reduced.

Enhanced diagnostic information can be achieved.

Abstract

Characterization of microstructures in live tissues is one of the keys to diagnosing early stages of pathology and understanding disease mechanisms. However, the extraction of reliable information on biomarkers based on microstructure details is still a challenge, as the size of features that can be resolved with non-invasive Magnetic Resonance Imaging (MRI) is orders of magnitude larger than the relevant structures. Here we derive from quantum information theory the ultimate precision limits for obtaining such details by MRI probing of water-molecule diffusion. We show that already available MRI pulse sequences can be optimized to attain the ultimate precision limits by choosing control parameters that are uniquely determined by the expected size, the diffusion coefficient and the spin relaxation time $T_{2}$. By attaining the ultimate precision limit per measurement, the number of measurements and the total acquisition time may be drastically reduced compared to the present state of the art. These results will therefore allow MRI to advance towards unravelling a wealth of diagnostic information.