Accelerated MRI via Variable Density Sampling and Compressed Sensing

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Solution Overview

Problem

Current cine DENSE imaging techniques face challenges with long image acquisition times and low signal-to-noise ratio (SNR), which complicates the analysis of myocardial strain due to cardiac motion and the need to preserve phase information.

Innovation Solution

The method involves accelerated variable-density sampling with phase-contrast displacement encoding, combined with parallel imaging and compressed sensing for magnetic resonance data acquisition and reconstruction, utilizing techniques like variable-density spiral sampling and Block LOw-rank Sparsity with Motion-guidance (BLOSM) to enhance image quality and reduce artifacts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional cine DENSE imaging is used to maintain high spatial resolution and phase information, then myocardial strain analysis accuracy is improved, but image acquisition time becomes long and signal-to-noise ratio becomes low

Engineering Contradiction:

Improvemyocardial strain analysis accuracyVSAvoidimage acquisition time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The imaging process is divided into multiple segments: (1) acquisition of fully-sampled reference data for a limited field of view, (2) acquisition of accelerated variable-density sampled data for the complete field of view, and (3) reconstruction that combines both datasets. This segmentation allows different sampling strategies to be applied to different portions of the imaging task, resolving the contradiction between comprehensive coverage and acquisition time.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Fully-sampled reference data is acquired first for a limited field of view before the accelerated imaging. This preliminary action provides high-quality reference information that can be combined with the subsequently acquired accelerated data, allowing the main imaging to use aggressive undersampling while maintaining overall image quality through the combination process.

Inventive Principle:

Principle #10Preliminary action

2Measurement precision

If conventional cine DENSE imaging is used to preserve phase information, then displacement encoding accuracy is improved, but signal-to-noise ratio becomes low

Engineering Contradiction:

Improvedisplacement encoding accuracyVSAvoidsignal-to-noise ratio

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The invention merges two types of data: fully-sampled reference data with high signal-to-noise ratio but limited field of view, and accelerated variable-density sampled data with broader coverage but lower signal-to-noise ratio. The combination in the reconstruction process integrates the high-quality reference information with the comprehensive accelerated data, achieving both high displacement encoding accuracy and improved signal-to-noise ratio.

Inventive Principle:

Principle #5Merging (Combining)

3Productivity

If accelerated variable-density sampling is used to reduce image acquisition time, then productivity is improved, but image quality and signal-to-noise ratio worsen

Engineering Contradiction:

Improveimaging speedVSAvoidimage quality

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

Different sampling densities are applied to different regions of k-space: the center region receives full sampling to capture low-frequency information and maintain image quality, while the peripheral regions receive variable-density undersampling to reduce acquisition time. This local differentiation of sampling quality allows accelerated imaging while preserving essential image characteristics.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention transitions from a single sampling strategy to a multi-dimensional approach by combining data from two different sampling regimes (fully-sampled reference and accelerated variable-density sampled). This dimensional expansion in the data acquisition space allows the system to achieve both high speed and high quality by synthesizing information from multiple sources.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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

This approach significantly reduces image acquisition time and improves SNR, allowing for high-quality myocardial strain analysis with accelerated cine DENSE imaging, enabling faster and more reliable clinical assessments.

Implementation Method 1

tissue displacement is encoded as a phase of a stimulated-echo signal

Methodology Applied

Scientific EffectPhase-contrast displacement encoding:

Implementation Method 2

acquiring magnetic resonance data associated with a physiological activity

Methodology Applied

Scientific EffectMagnetic resonance:

Data Source

PatentUS10143384B2Systems and methods for accelerated imaging using variable density sampling and compressed sensing with parallel imaging

Publication Date: 2018.12.04 UNIV OF VIRGINIA PATENT FOUND

AI summary

Some aspects of the present disclosure relate to accelerated imaging using variable-density sampling and compressed sensing with parallel imaging. In one embodiment, a method includes acquiring magnetic resonance data associated with a physiological activity in an area of interest of a subject. The acquiring includes performing accelerated variable-density sampling with phase-contrast displacement encoding. The method also includes reconstructing, from the acquired magnetic resonance data, images corresponding to the physiological activity in the area of interest. The reconstructing includes performing parallel imaging and compressed sensing.