Zero Echo Time fMRI for Low-Noise, Artifact-Resistant Imaging

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Solution Overview

Problem

Conventional Gradient Recalled Echo (GRE)-Echo Planar Imaging (EPI)-based Blood Oxygen Level Dependent (BOLD) functional magnetic resonance imaging (fMRI) suffers from sensitivity to magnetic field inhomogeneity artifacts, high acoustic noise, poor spatial specificity, and low sensitivity, which limits its effectiveness in applications such as pediatric and awake animal studies.

Innovation Solution

Utilizing Zero Echo Time (ZTE) magnetic resonance imaging sequences with optimized pulse sequence parameters and spatial encoding gradients to minimize acquisition delay, reduce acoustic noise, and enhance sensitivity to T1 changes, particularly in tissue oxygenation, thereby improving spatial specificity and sensitivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If GRE-EPI sequence is used for fMRI, then sensitivity to BOLD signal is improved, but sensitivity to magnetic field inhomogeneity artifacts increases

Engineering Contradiction:

ImproveBOLD signal sensitivityVSAvoidmagnetic field inhomogeneity artifacts

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the fundamental imaging parameters by using Zero Echo Time (ZTE) sequence instead of conventional GRE-EPI. This involves setting the echo time to zero and using a radial sampling trajectory in k-space, which fundamentally alters how the MRI signal is acquired and makes the sequence insensitive to magnetic field inhomogeneities while maintaining BOLD signal detection capability.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If GRE-EPI sequence is used for fMRI, then BOLD signal detection is improved, but acoustic noise increases

Engineering Contradiction:

ImproveBOLD signal detectionVSAvoidacoustic noise

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The ZTE sequence uses periodic radial sampling of k-space with optimized timing that minimizes gradient switching frequency and amplitude. The sequence parameters are specifically tuned to reduce the duty cycle of gradient coils while maintaining sufficient sampling rate for functional imaging, thereby dramatically reducing acoustic noise generation.

Inventive Principle:

Principle #19Periodic action

3Adaptability or versatility

If GRE-EPI sequence is used for fMRI, then functional imaging capability is maintained, but spatial specificity to neuronal activation decreases

Engineering Contradiction:

Improvefunctional imaging capabilityVSAvoidspatial specificity

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent exploits the unique parameter space of ZTE sequences, particularly the ability to achieve very short echo times and use low flip angles with long repetition times. This parameter regime enhances the contribution of T1-weighted contrast and arterial blood signal, which provide superior spatial specificity to the site of neuronal activation compared to conventional T2*-weighted BOLD imaging.

Inventive Principle:

Principle #35Parameter changes

4Adaptability or versatility

If GRE-EPI sequence is used for fMRI, then functional imaging is achieved, but sensitivity is limited

Engineering Contradiction:

Improvefunctional imagingVSAvoidsensitivity

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The ZTE sequence enables continuous sampling of the MRI signal with minimal dead time between excitations. The optimized pulse sequence parameters and radial sampling approach maximize the utilization of available signal while minimizing gaps in data acquisition, thereby improving the overall sensitivity and signal-to-noise ratio for functional imaging.

Inventive Principle:

Principle #20Continuity of useful action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

ZTE-fMRI provides improved spatial specificity and sensitivity to neuronal activation, reducing artifacts and noise, allowing for higher resolution and more accurate functional MRI without the need for invasive contrast agents.

Implementation Method 1

Conventional MRI involves the excitation of the hydrogen protons (hereafter termed spins) that are precessing in a strong magnetic field following a radiofrequency (RF) pulse

Methodology Applied

Scientific EffectMagnetic resonance:

Implementation Method 2

In the time between successive RF pulses, the MRI signal is spatially encoded by the gradient magnetic fields which are conventionally switched on and off between every RF pulse repetition

Methodology Applied

Scientific EffectMagnetic field gradient encoding: Magnetic Field

Implementation Method 3

utilizing Zero Echo Time (ZTE) magnetic resonance imaging sequences with optimized pulse sequence parameters and spatial encoding gradients to minimize acquisition delay

Methodology Applied

Scientific EffectZero echo time imaging:

Implementation Method 4

measuring inflow and T1 changes as a proxy of neural activity changes of a subject using the at least one MRI image

Methodology Applied

Scientific EffectT1 relaxation:

Data Source

PatentUS12551131B2Methods and systems for functional magnetic resonance imaging with a Zero Echo Time pulse-sequence

Publication Date: 2026.02.17 THE UNIV OF NORTH CAROLINA AT CHAPEL HILL

AI summary

This specification describes systems and methods for using Zero Echo Time (ZTE) magnetic resonance imaging (MRI) sequences for applications to functional MRI (fMRI). In some examples, a system for functional magnetic resonance imaging includes a magnetic resonance imaging (MRI) scanner and a control console implemented on at least one processor. The control console is configured for executing, using the MRI scanner, a zero echo time (ZTE) pulse sequence; acquiring, using the MRI scanner, magnetic resonance data in response to the ZTE pulse sequence; and constructing at least one MRI image using the magnetic resonance data and measuring tissue oxygenation (PtO2)-related T1 changes as a proxy of neural activity changes of a subject using the at least one MRI image.