MR Acquisition Control for Sliding MultiSlice Distortion
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Solution Overview
Problem
The preparation and implementation of MR measurements with continuous table feed are hindered by specific requirements related to the number of slices and user parameters, particularly in the Sliding MultiSlice (SMS) technique, due to nonlinearity of gradient fields and inhomogeneity of the B0 field, leading to image distortions and complexities in workflow control.
Innovation Solution
The method automatically determines the number of slices excited and read out per repetition of the basic sequence based on parameters affecting image contrast and resolution, subdividing k-space into segments to ensure consistent data acquisition, reducing acquisition-dependent differences and simplifying the workflow by automating the selection of k-space lines and table speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the number of slices excited and read out per repetition is manually preset by the user, then the ease of operation is improved, but the device complexity increases due to the need to satisfy specific correlations between number of slices, k-space segments, table speed, and additional parameters
Solution Approach 1:
The control device automatically determines the number of slices excited and read out per repetition based on user-selected parameters (image contrast, resolution, k-space segments), eliminating the need for manual configuration of complex parameter correlations. The system serves itself by deriving the slice count from higher-level user intentions rather than requiring direct specification of all interdependent parameters.
2Manufacturing precision
If the number of k-space segments per slice is increased to reduce acquisition-dependent differences, then the image quality is improved, but the measurement time increases
Solution Approach 1:
The control device dynamically adjusts the number of k-space segments per slice based on the selected table speed and other measurement parameters. When higher table speeds are chosen to reduce measurement time, the system automatically increases the number of k-space segments to maintain image quality, creating a dynamic balance between speed and precision rather than using fixed values.
3Productivity
If the table speed is increased to reduce measurement time, then the productivity is improved, but the acquisition-dependent differences due to gradient nonlinearity and B0 inhomogeneity increase
Solution Approach 1:
The system changes multiple parameters simultaneously - when table speed is increased to improve productivity, the control device automatically adjusts the number of k-space segments per slice and other acquisition parameters to compensate for increased distortion from gradient nonlinearity and B0 inhomogeneity, maintaining image quality while achieving faster measurement.
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 reduces image distortions, simplifies the preparation of MR measurements, and enhances the signal-to-noise ratio by ensuring consistent data acquisition across slices, thereby improving the quality and consistency of MR images.
Implementation Method 1
MR signals are acquired from a predetermined volume segment given continuous feed of the patient bed. The volume segment is subdivided into parallel slices with a constant slice interval, such that the direction of the table feed is perpendicular to the slice plane.
Data Source
AI summary
In a method and a device to control the workflow of an MR measurement in a magnetic resonance system, a predetermined volume segment is subdivided into parallel slices with a predetermined slice interval and measured with a continuous table feed. Apart from a start phase and an end phase of the MR measurement, multiple slices of the examination subject are excited and read out in every repetition of the underlying basic sequence, and these multiple slices are located in an active volume inside the magnetic resonance system. The number of slices excited and read out per repetition of the underlying basic sequence is selected automatically depending in particular on the parameters determining an image contrast and an image resolution, and thus cannot be freely set by a user of the magnetic resonance system.