Interleaved Stimulated Echo MRI Sub-Volume Acquisition
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Solution Overview
Problem
Magnetic resonance imaging techniques using stimulated echoes require longer scan times due to the need for synchronized radiation of three RF pulses, limiting the efficiency of data acquisition.
Innovation Solution
Interleaving the generation and acquisition of echo signals in different sub-volumes during the mixing time of a stimulated echo experiment, allowing additional RF pulses to be applied outside the coherence path of the prepared spin coherences, enabling simultaneous data acquisition from multiple sub-volumes without impairing the prepared spin coherences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If stimulated echo methods are used to image tissues with short T2 relaxation times or at ultra-high fields, then image quality is improved, but scan time increases significantly
Solution Approach 1:
The imaging volume is divided into multiple sub-volumes (e.g., slices or slabs) that can be excited and imaged independently. By segmenting the volume and using separate RF pulse trains for each sub-volume, the method enables parallel acquisition while maintaining the stimulated echo sequence benefits for each segment, thereby reducing total scan time without compromising image quality
Solution Approach 2:
Multiple stimulated echo acquisitions for different sub-volumes are merged into a single integrated scan sequence. The method combines multiple RF pulse trains and data acquisition streams into one coordinated process, allowing simultaneous or interleaved imaging of multiple sub-volumes within the same scan time frame, thus reducing overall acquisition time while maintaining image quality
2Reliability
If three RF pulses are radiated in synchronized manner to generate stimulated echo, then echo signal is obtained, but scan time increases
Solution Approach 1:
The method employs periodic RF pulse trains where the three RF pulses for stimulated echo are repeated in a systematic periodic manner across multiple sub-volumes. By organizing the pulse sequence periodically and interleaving different sub-volume acquisitions, the method maintains reliable echo signal generation while reducing the total number of sequential operations required, thereby decreasing scan time
Solution Approach 2:
The scan sequence is designed to maintain continuous useful action by eliminating idle periods between RF pulse trains. While one sub-volume is being excited and imaged, other sub-volumes are simultaneously prepared or being acquired. This continuous utilization of the MRI system across multiple parallel streams maintains echo signal reliability while maximizing time efficiency and reducing total scan duration
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 scan time by a factor of two to five or more, particularly in diffusion imaging, while maintaining image quality, and is adaptable for various scan parameters and high-field strengths.
Implementation Method 1
the object's nuclear spins align along the main magnetic field. To trigger nuclear spin resonances, radiofrequency (RF) pulses are radiated into the object e.g. for excitation or refocusing signals by the nuclear spin resonances that are triggered are measured
Implementation Method 2
the object to be imaged is positioned in a magnetic resonance scanner in a strong, static, homogeneous basic magnetic field, also known as a B0 field, having field strengths of 0.2 to 7 tesla or more, so that the object's nuclear spins align along the main magnetic field
Implementation Method 3
For spatially encoding the scan data, rapidly switched magnetic gradient fields are superimposed on the basic magnetic field
Data Source
AI summary
In a method and magnetic resonance (MR) apparatus for acquiring MR scan data of an object by execution of a scan sequence in which pulses, at least three RF pulses are radiated for generating an echo signal in a first sub-volume, at a point in time between two of the at least three RF pulses associated with the first sub-volume, at least one other RF pulse is radiated so as to generate an echo signal in another sub-volume, the other sub-volume being different from the first sub-volume. The resulting the echo signals are received and entered into k-space so as to form a datafile that is accessible for reconstructing image data of the object.