MRI Pulse Sequence Timing for Slice Crosstalk Control
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Solution Overview
Problem
Magnetic resonance imaging (MRI) experiences slice cross-talk due to finite bandwidth of RF excitation pulses, leading to signal loss and contrast changes, particularly in multi-layer MR measurements, which users cannot effectively address without knowledge of underlying physical relationships.
Innovation Solution
A method for determining and adjusting time intervals between adjacent layer excitations in MRI pulse sequences based on pulse sequence parameters, tissue parameters, and quality parameters to prevent or reduce crosstalk artifacts, using a magnetic resonance system with a control device and distance determination unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If layer spacing is reduced to increase measurement coverage, then productivity is improved, but slice cross-talk increases causing signal loss and contrast changes
Solution Approach 1:
The system performs preliminary calculation of minimum time intervals between adjacent layer excitations based on pulse sequence parameters and tissue characteristics before data acquisition. This preliminary action prevents slice cross-talk by ensuring adequate recovery time is allocated between excitations of adjacent layers, while still allowing tight spacing for efficient coverage.
Solution Approach 2:
The patent dynamically adjusts the time intervals between excitations of adjacent layers based on calculated minimum intervals derived from pulse sequence parameters and tissue properties. This dynamic adjustment allows the system to optimize the balance between layer spacing for coverage and time intervals for preventing cross-talk, adapting to different measurement conditions.
2Object-affected harmful factors
If time intervals between layer excitations are increased to prevent cross-talk, then slice cross-talk is reduced, but measurement time is prolonged
Solution Approach 1:
The system calculates and applies specific time interval parameters between excitations of adjacent layers based on pulse sequence parameters and tissue characteristics. By precisely determining the minimum required time interval, the system prevents cross-talk while minimizing the time penalty, avoiding both excessive spacing and insufficient recovery time.
3Object-affected harmful factors
If users manually adjust layer spacing or time intervals to prevent cross-talk, then slice cross-talk can be reduced, but device complexity increases and ease of operation decreases
Solution Approach 1:
The system automatically calculates the minimum time intervals between excitations of adjacent layers based on pulse sequence parameters and tissue characteristics without requiring user intervention. The control device performs these calculations and adjusts the timing parameters automatically, allowing users to benefit from cross-talk prevention without needing specialized knowledge of the underlying physics or manual adjustment capabilities.
4Object-affected harmful factors
If restrictive minimum layer spacing is enforced to prevent cross-talk, then slice cross-talk is reduced, but adaptability decreases
Solution Approach 1:
Instead of enforcing a fixed minimum layer spacing restriction, the system dynamically calculates the minimum time interval between excitations of adjacent layers based on pulse sequence parameters and tissue characteristics. This allows flexible layer spacing adaptation to different measurement requirements while preventing cross-talk through appropriate timing adjustments specific to each measurement configuration.
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
Minimizes crosstalk artifacts while maintaining measurement efficiency by ensuring minimum time intervals between layer excitations, allowing for accurate data acquisition without unnecessary prolongation of the measurement time.
Implementation Method 1
Magnetic resonance imaging (MRI) is a well-known technique used to generate images of the interior of an object. This causes the object's nuclear spins to align with the background magnetic field. To trigger nuclear spin resonances, high-frequency excitation pulses (RF pulses) are applied to the object.
Implementation Method 2
Rapidly switched magnetic gradient fields are superimposed on the background magnetic field to spatially encode the measurement data.
Implementation Method 3
determining a minimum time interval between excitations of adjacent layers performed within the pulse sequence based on pulse sequence parameters, tissue parameters of the examination area of the object
Data Source
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AI summary
In an inventive method for acquiring data from a test object in at least two layers, a measurement protocol is loaded which is intended to acquire the data by means of a pulse sequence. Time intervals between excitations of adjacent layers performed within the pulse sequence and the corresponding minimum intervals are determined. From this, time intervals between excitations of adjacent layers performed within the pulse sequence are determined and adjusted before the measurement protocol is executed with the adjusted time intervals.By determining, in particular automatically, a minimum time interval between excitations of adjacent layers carried out within the pulse sequence and by selectively adjusting, in particular automatically, only the time intervals between excitations of adjacent layers that need adjusting within the pulse sequence, on the one hand, a distortion of measurement results can be cleverly avoided, while on the other hand, the measurement time of the selected measurement protocol is not unnecessarily increased, and the user is not unintentionally restricted in the choice of layers to be excited.