Temperature-Dependent Gradient Pre-emphasis for MRI Trajectory Correction

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Solution Overview

Problem

Magnetic resonance (MR) imaging faces challenges in accurately reconstructing images due to temperature-dependent deviations in gradient waveforms and k-space trajectories, leading to artifacts such as ghosting and geometric distortions, particularly in non-Cartesian trajectories.

Innovation Solution

Developing gradient system characterization functions based on measured temperature deviations, allowing for pre-emphasis corrections to be applied during imaging, which involves setting gradient coils to target temperatures, measuring their behavior, and calculating pre-emphasized gradients to correct for k-space trajectory deviations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If rapid acquisition methods with high gradient amplitudes and slew rates are used, then imaging speed is improved, but k-space trajectory deviations increase causing image artifacts

Engineering Contradiction:

Improveimaging speedVSAvoidk-space trajectory accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The system performs preliminary measurement of the gradient system's impulse response function and derives a pre-emphasis filter before actual imaging. This pre-characterization allows the system to predict and compensate for trajectory deviations that will occur during rapid acquisition, enabling high imaging speed while maintaining k-space trajectory accuracy through pre-applied corrections

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system measures the actual gradient system behavior using an impulse response function and uses this feedback information to derive a pre-emphasis filter. This closed-loop approach continuously characterizes the gradient system's performance and adjusts the gradient waveforms accordingly, allowing rapid acquisition methods to be used while compensating for the resulting trajectory deviations

Inventive Principle:

Principle #23Feedback

2Adaptability or versatility

If temperature variations occur in gradient coils, then system adaptability is improved, but gradient waveform deviations increase causing image artifacts

Engineering Contradiction:

Improvetemperature range operationVSAvoidgradient waveform accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The system measures the impulse response function at different temperature conditions and derives temperature-dependent pre-emphasis filters. By characterizing how the gradient system's frequency response changes with temperature and applying corresponding corrections, the system maintains gradient waveform accuracy across a wide temperature range, enabling adaptable operation without sacrificing precision

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11112472B2Pre-emphasis techniques based on temperature dependent gradient system behavior for trajectory correction in magnetic resonance imaging

Publication Date: 2021.09.07 SIEMENS HEALTHINEERS AG

AI summary

A gradient system characterization function (e.g., a gradient system transfer function) may be developed by measuring a behavior of the MR device at a target temperature and developing at least one gradient system characterization function for a gradient coil of a magnetic resonance (MR) device at the target temperature based on the measured behavior. A patient may be subsequently imaged by the MR device, wherein the imaging process comprises measuring a temperature of a gradient coil, determining a gradient system characterization function at the measured temperature, calculating a pre-emphasized gradient of the gradient coil, and imaging the patient using the pre-emphasized magnetic field component.