K-space Data Acquisition Using Forward Reverse Phase Encoding Gradients
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Solution Overview
Problem
Magnetic resonance imaging (MRI) techniques, particularly echo planar imaging (EPI), face challenges with geometric distortion and reduced image resolution due to partial k-space acquisition methods, which affect diffusion weighted imaging (DWI) and result in fuzziness and the Gibbs ring effect.
Innovation Solution
A k-space data acquisition method that involves acquiring data using both forward and reverse phase encoding gradients, combining the data to form complete k-space with non-zero filling, and applying phase and distortion corrections to improve image resolution and reduce artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If partial k-space acquisition is used to reduce echo time and improve signal-to-noise ratio, then scan time is reduced by half, but image resolution is reduced and obvious fuzziness occurs in the phase encoding direction
Solution Approach 1:
The patent segments k-space acquisition into two separate acquisitions: one with forward phase encoding gradient and another with reverse phase encoding gradient. Each acquisition captures half of the k-space data, and the two segments are later combined to form complete k-space data, thereby achieving full image resolution while maintaining reduced scan time
Solution Approach 2:
The patent applies reverse phase encoding gradient in the second acquisition to invert the phase encoding direction. This allows the second half of k-space data to be acquired with opposite phase encoding, and when combined with the first acquisition data, the complementary information fills in the missing details, eliminating fuzziness while maintaining fast imaging
2Ease of manufacture
If direct zero-filling reconstruction is used to fill unsampled k-space with zeroes, then reconstruction is simple, but Gibbs ring effect occurs due to data truncation
Solution Approach 1:
The patent converts the potential harm of data truncation into a benefit by using the reverse phase encoding acquisition to capture the missing k-space data that would otherwise be zero-filled. The reverse phase encoding naturally acquires the complementary information needed to avoid truncation artifacts while maintaining reconstruction simplicity
3Productivity
If echo planar imaging method is used to achieve fast imaging, then measurement time is short, but geometric distortion occurs in the images
Solution Approach 1:
The patent uses reverse phase encoding gradient to acquire the second half of k-space data with inverted phase encoding direction. This inversion compensates for the geometric distortion inherent in EPI by capturing complementary spatial information that, when combined with the forward encoding data, corrects the distortion while maintaining fast imaging speed
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 method enhances image quality by correcting distortions and maintaining a high signal-to-noise ratio, reducing the need for complex calculations and avoiding image loss, thus improving diagnostic capabilities in MRI systems.
Implementation Method 1
Magnetic resonance imaging (MRI) is a technology in which the phenomenon of magnetic resonance is utilized for the purpose of imaging
Implementation Method 2
operating an MRI scanner to acquired and enter data in an upper-half portion of k-space in a memory under a forward phase encoding gradient of the MRI scanner
Data Source
AI summary
In a method and apparatus to acquire magnetic resonance data from a subject and to enter the acquired data into k-space, data entered in an upper-half portion of k-space are acquired under a forward phase encoding gradient of the scanner so as to obtain a first portion of k-space data, and data in a lower-half portion of k-space are acquired under a reverse phase encoding gradient of the scanner so as to obtain a second portion of k-space data. The first portion of k-space data and the second portion of k-space data are combined to form complete k-space data, wherein the first portion of k-space data and the second portion of k-space data each constitute at least half of the complete k-space data.