MRI Reference Data Intensity Scaling for SMS-HASTE Reconstruction
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Solution Overview
Problem
The challenge in magnetic resonance imaging is the long recording time and image quality issues due to different relaxation behaviors and contrast differences in reference data recorded at different time portions during SMS-HASTE sequences, leading to slice cross-talk and aliasing.
Innovation Solution
A method that distributes slice stacks into groups, simultaneously excites slices using multiband pulses, records reference data after slice scan data, and adjusts intensity using a scaling factor to align intensity progressions, avoiding recording data from non-included slices and minimizing temporal spacing differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If reference data is recorded at different time portions during SMS-HASTE sequences, then the recording time is reduced, but image quality deteriorates due to different relaxation behaviors and contrast differences
Solution Approach 1:
The patent applies parameter changes by introducing a scaling factor that adjusts the reference data based on the temporal spacing from the multiband excitation pulse. This compensates for relaxation behavior differences and maintains consistent contrast across reference data recorded at different time portions, resolving the contradiction between reduced recording time and maintained image quality
Solution Approach 2:
The patent applies preliminary action by calculating and applying the scaling factor to reference data before the data reconstruction process. This preliminary adjustment ensures that contrast differences are corrected in advance, preventing image quality deterioration while maintaining the accelerated recording timeline
2Reliability
If reference data is recorded after slice scan data, then movement artifacts are reduced, but temporal spacing differences cause contrast inconsistency
Solution Approach 1:
The patent calculates the scaling factor based on the specific temporal spacing between the multiband excitation pulse and each reference data recording time. This parameter adjustment compensates for relaxation differences caused by the time delay, maintaining contrast consistency while preserving the movement artifact reduction benefit of post-scan reference data recording
3Productivity
If multiband excitation pulses are used to simultaneously excite multiple slices, then recording time is reduced, but slice cross-talk and aliasing occur
Solution Approach 1:
The patent uses coil sensitivity data obtained from reference data as feedback to separate the compressed slice scan data set into individual slice data sets. This feedback mechanism resolves the slice cross-talk and aliasing caused by simultaneous multiband excitation, maintaining both recording speed and slice separation accuracy
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 enhances image quality by reducing movement artifacts and slice cross-talk, ensuring consistent contrast and efficient data reconstruction, even with single-shot techniques like HASTE.
Implementation Method 1
nuclear spins of the examination object, in particular a patient, are subjected in the examination region to the most homogeneous possible strong main magnet field, in which they become aligned. The nuclear spins can be excited by radiofrequency excitation pulses
Implementation Method 2
The spatial encoding of the recorded magnetic resonance signals can therein be achieved by means of a commonly-used gradient switching in two directions (two-dimensional gradient encoding)
Data Source
AI summary
A computer-implemented method for operating a magnetic resonance facility for recording a magnetic resonance data set may include, after the recording of all the reference data, before the establishment of the calibration data, an intensity adjustment of the reference data with respect to the different temporal position of time portions in which they were recorded is performed for the recording of the associated slice scan data. The intensity adjustment may include establishing a representative intensity value for each reference data set of a slice, forming an intensity progression for each time portion from the intensity values of the reference data sets recorded in the time portion, establishing a scaling of the intensity progressions relative to one another, and performing the intensity adjustment based on the scaling.