Respiratory Gated MRI Data Acquisition for Artifact Reduction
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Solution Overview
Problem
Existing magnetic resonance imaging (MRI) techniques face challenges in accurately acquiring data due to respiratory movement, leading to artifacts like ghosting, blurring, and intensity losses, particularly in thoracic and abdominal regions, which can result in overlooked lesions and inefficient measurement processes.
Innovation Solution
A method that incorporates both respiratory position and phase measurements to determine whether individual MRI measurements should be included in the final data set for image reconstruction, using navigator measurements to assess the momentary respiratory phase and adjust the acquisition accordingly, thereby reducing the overall variation in respiratory position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If respiratory gating is used to reduce artifacts, then image quality is improved, but measurement time is extended
Solution Approach 1:
The k-space is divided into multiple segments, and respiratory gating is applied selectively to specific segments rather than the entire measurement process. This allows artifact reduction in critical regions while maintaining faster acquisition in other regions, resolving the contradiction between image quality and measurement time.
Solution Approach 2:
Different gating strategies are applied to different k-space segments based on their sensitivity to respiratory artifacts. Segments more susceptible to artifacts receive gating, while less sensitive segments are acquired without gating, optimizing the balance between image quality and measurement time.
2Reliability
If respiratory triggering with navigators is used, then respiratory movement is synchronized, but the scanning rate is limited by the navigator sequence duration
Solution Approach 1:
The measurement process is segmented into navigator acquisition phases and imaging acquisition phases. By separating these functions temporally and spatially, the system can perform rapid imaging during exhalation phases without being constrained by the continuous navigator sequencing requirement, thereby increasing the scanning rate while maintaining respiratory synchronization.
3Speed
If external sensors are used for respiration detection, then scanning rate can be increased, but the imaging measurement must be uninterrupted
Solution Approach 1:
The system uses self-navigated respiratory gating where the MR signals themselves (navigators) are used to detect respiratory movement and control the gating, eliminating the need for external sensors. This self-service approach allows flexible measurement scheduling and interruption without requiring additional hardware or continuous external monitoring.
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 the variation in respiratory position during data acquisition, leading to improved image quality by minimizing artifacts and enhancing the efficiency of the MRI process.
Implementation Method 1
the examination subject is placed in a magnetic resonance imaging scanner, in a strong, static, homogenous base magnetic field, also called a B0 field
Implementation Method 2
the examination subject is irradiated with high frequency excitation pulses (RF pulses), the triggered magnetic resonance signals are detected
Implementation Method 3
For the spatial encoding of the measurement data, rapidly activated magnetic gradient fields are superimposed on the base magnetic field
Data Source
AI summary
In a method for acquisition of a measurement data set of a respirating examination subject by magnetic resonance technology, the measurement data set is acquired by numerous individual measurements, wherein, for each individual measurement, a respiratory position and a respiratory phase are determined, based on which it is decided whether the individual measurement is to be included in the final measurement data set from which an image data set is reconstructed.