MR Imaging Readout Gradient Pulse Timing and Frequency Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Magnetic Resonance (MR) imaging systems experience interference effects, particularly at the start of selection periods, which affect the quality of the reconstructed MR images.
Innovation Solution
Introducing a random component during the processing of MR signals by randomly or pseudo-randomly delaying selection periods and/or shifting the center frequency for frequency implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If readout gradient pulses are switched with ADC activation during readout periods, then MR signals can be acquired and processed, but interference effects and artifacts occur at the beginning of readout periods
Solution Approach 1:
The invention applies preliminary action by introducing a delay between the start of the readout gradient pulse and the activation of the ADC. This delay allows the gradient pulse to establish a stable linear ramp phase before signal acquisition begins, preventing interference effects and artifacts that would otherwise occur at the beginning of the readout period. The delay time is specifically chosen to ensure the gradient has reached a stable state before ADC switching.
Solution Approach 2:
The invention applies dynamics by making the delay time variable rather than fixed. The delay time is adjusted based on the specific readout gradient pulse characteristics and timing requirements, allowing optimal synchronization between gradient pulse establishment and ADC activation. This dynamic adjustment ensures consistent signal quality across different readout periods while maintaining flexibility in the acquisition sequence.
2Measurement precision
If readout gradient pulses have linearly rising edges (gradient ramps), then position coding can be achieved, but disturbances occur at the beginning of readout periods
Solution Approach 1:
The invention applies preliminary action by introducing a delay between the start of the readout gradient pulse and the activation of the ADC. This delay allows the gradient pulse to establish a stable linear ramp phase before signal acquisition begins, preventing interference effects and artifacts that would otherwise occur at the beginning of the readout period. The delay time is specifically chosen to ensure the gradient has reached a stable state before ADC switching.
3Productivity
If ADC and NCOs are switched simultaneously, then readout and frequency conversion can proceed, but glitches occur at the beginning of readout periods
Solution Approach 1:
The invention applies preliminary action by introducing a delay between the start of the readout gradient pulse and the activation of the ADC. This delay allows the gradient pulse to establish a stable linear ramp phase before signal acquisition begins, preventing interference effects and artifacts that would otherwise occur at the beginning of the readout period. The delay time is specifically chosen to ensure the gradient has reached a stable state before ADC switching.
Solution Approach 2:
The invention applies beforehand cushioning by using the delay period as a buffer that absorbs the harmful effects of simultaneous switching. During this delay interval, the system allows the gradient pulse to stabilize without ADC activation, effectively cushioning against the glitches that would result from immediate simultaneous switching of ADC and NCOs.
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 interference effects and artifacts in the MR images by introducing incoherence between different selection periods, thereby improving the quality of the reconstructed images.
Implementation Method 1
The precession, or transition of the spins from this excited state to a lower-energy state, generates an alternating electromagnetic field in response, which can be detected as an MR signal via receiving antennas
Implementation Method 2
Using magnetic gradient fields, for example as gradient pulses, a position coding can be imprinted on the signals
Implementation Method 3
Magnetic resonance (MR) imaging systems are imaging devices that use a strong external magnetic field to align the nuclear spins of an object under investigation
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
In a method for MR imaging, for each of a plurality of readout gradient pulses (19a, 19b, 19c, 24a, 24b, 24c, 24d, 24e, 24f) during a respective readout period (20a, 20b, 20c, 22a, 22b, 22c, 22d, 22e, 22f) (4, 6) an MR signal is acquired and an MR image is generated depending on this. A start time of the respective readout period (20a, 20b, 20c, 22a, 22b, 22c, 22d, 22e, 22f) with respect to a start time of the respective readout gradient pulse (19a, 19b, 19c, 24a, 24b, 24c, 24d, 24e, 24f) is delayed by a delay duration which is randomly or pseudorandomly selected from two or more predefined time values, and/or to generate the MR image the acquired MR signals are processed, wherein the processing includes a frequency conversion according to a center frequency which is randomly or pseudorandomly selected from two or more predefined frequency values.