Asymmetric Radial MRI Sampling for Faster Cardiac Cine Imaging

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Solution Overview

Problem

Conventional MRI techniques for cardiac cine imaging require breath-holds and regular heartbeats, limiting their application, and symmetric radial sampling schemes do not fully exploit the complex conjugate symmetry in k-space, leading to suboptimal acquisition times.

Innovation Solution

Implementing an interleaved-angle asymmetric radial sampling scheme with compressed-sensing reconstruction methods to acquire and process cine images, reducing repetition time and data acquisition time without significant degradation in image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If symmetric radial sampling scheme is used, then full echoes are formed for acquisition, but redundancy is introduced by ignoring complex conjugate symmetry in k-space

Engineering Contradiction:

Improvedata completenessVSAvoidacquisition time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies asymmetry by using asymmetric radial sampling schemes that exploit the complex conjugate symmetry properties of k-space. Instead of symmetric sampling that treats all directions equally, the method samples only asymmetric portions of k-space (e.g., sampling one side more than the other), thereby eliminating redundant measurements while maintaining complete image reconstruction capability through compressed sensing algorithms.

Inventive Principle:

Principle #4Asymmetry

2Productivity

If repetition time is reduced, then frame rate is increased, but image quality may degrade

Engineering Contradiction:

Improveframe rateVSAvoidimage quality

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the sampling parameters by transitioning from symmetric to asymmetric radial sampling patterns. This parameter change allows for shorter repetition times because fewer k-space points need to be acquired per frame, thereby increasing frame rate while maintaining image quality through the use of compressed sensing reconstruction that can handle the undersampled asymmetric data.

Inventive Principle:

Principle #35Parameter changes

3Loss of time

If Cartesian bSSFP with partial Fourier is used, then TR is reduced, but reconstruction quality is compromised

Engineering Contradiction:

ImproveTR durationVSAvoidreconstruction quality

Core Design Contradiction:

Loss of timeVSManufacturing precision

Solution Approach 1:

The patent substitutes the conventional Cartesian sampling mechanics with radial sampling mechanics. Instead of acquiring data along Cartesian grid lines with partial Fourier truncation, the method uses radial trajectories that naturally pass through the center of k-space and can be asymmetrically sampled. This substitution enables shorter TR times while maintaining reconstruction quality through compressed sensing, avoiding the quality loss associated with partial Fourier methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS9918639B2Magnetic resonance imaging with asymmetric radial sampling and compressed-sensing reconstruction

Publication Date: 2018.03.20 SIEMENS HEALTHINEERS AG

AI summary

A method for acquiring cine images using a magnetic resonance imaging (MRI) system includes selecting an asymmetric radial sampling scheme providing an asymmetric view of k-space corresponding to a desired image resolution. Radial k-space data is acquired using the asymmetric radial sampling scheme, wherein slice-orientation of the radial k-space data is continuously modified while acquiring the radial k-space data. A plurality of cine images are reconstructed from the radial k-space data using a compressed-sensing method.