Acquisition of data of an examination object by means of magnetic resonance with improved time management
Inventors
Koerzdoerfer, Gregor • Nittka, Mathias • Speier, Peter
Assignees
Publication Number
US-12360189-B2
Publication Date
2025-07-15
Expiration Date
2040-09-25
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Abstract
Techniques are disclosed for acquiring data of an examination object in at least two slices by means of a pulse sequence. Time intervals between excitations of neighboring slices and associated minimum intervals are determined. From these, time intervals to be adapted between excitations of neighboring slices are determined and adapted before a measurement protocol is executed, with the adapted time intervals. Through the determination of a minimum time interval between excitations of neighboring slices and the adaptation of the time intervals between excitations of neighboring slices, a falsification of measurement results can be avoided, measurement time of the chosen measurement protocol is not increased, and the user is not restricted in their choice of the slices to be excited.
Core Innovation
The invention relates to a method for acquiring data of an examination object by means of magnetic resonance imaging in at least two slices. It involves loading a measurement protocol for data acquisition with a pulse sequence, determining the time intervals between excitations of neighboring slices, and establishing minimum time intervals based on pulse sequence parameters, tissue parameters of the examination region, and selectable quality parameters. The time intervals to be adapted are identified as those shorter than the associated minimum time intervals, which are then adapted before execution so that no time interval falls below its minimum. An adapted pulse sequence with these adjusted time intervals is used for data acquisition.
The problem addressed is the slice crosstalk effect inherent in multi-slice magnetic resonance measurements, especially with small distances between slices. Real slice excitation profiles caused by RF excitation pulses of finite bandwidth excite spins outside the intended slice, resulting in undesired magnetization and pre-saturation effects in neighboring slices. This leads to signal losses, changes in contrast, and falsification of quantitative parameter maps. Users typically lack the detailed knowledge or slice excitation profiles to avoid these artifacts, and existing restrictions such as enforced minimum slice distances limit user flexibility.
The disclosed method automatically determines appropriate minimum time intervals between excitations of neighboring slices based on relevant parameters to avoid crosstalk artifacts while not unnecessarily increasing overall measurement time. Adaptations to time intervals involve inserting wait times between excitations or re-sorting slice excitation order while maintaining the predetermined chronological order. This approach preserves user freedom in slice selection and avoids significant interference with the measurement protocol, enabling artifact reduction without incurring substantial complexity or measurement time penalties.
Claims Coverage
The patent contains two independent claims: one directed to a method for acquiring magnetic resonance data with adapted time intervals between spatially adjacent slice excitations, and another directed to a magnetic resonance apparatus configured to perform this method. Additionally, there is an independent claim relating to a non-transitory computer-readable medium embodying computer program instructions for executing the method.
Method for time-adapted slice excitation in MR imaging
A method comprising loading a measurement protocol for acquiring data in at least two slices within a pulse sequence applied in a predetermined chronological excitation order; determining time intervals between excitations of spatially adjacent slices; determining a threshold time interval based on pulse sequence, tissue, and selectable quality parameters; identifying intervals below this threshold as to be adapted; adapting these intervals while maintaining the excitation order so that all adapted intervals meet or exceed the threshold; and acquiring data using the adapted pulse sequence.
Magnetic resonance apparatus configured for time-adapted slice excitation
An MR apparatus comprising a magnet, gradient circuitry, RF circuitry, and a controller configured to load a measurement protocol with a pulse sequence in a predetermined slice excitation order, determine time intervals between spatially adjacent slice excitations, determine threshold intervals based on pulse sequence, tissue, and quality parameters, identify intervals below this threshold, adapt these while maintaining excitation order to respect the threshold, and acquire data with the adapted pulse sequence.
Computer-readable medium with instructions for monitoring and adapting time intervals
A non-transitory computer-readable medium storing instructions executable by a controller of an MR apparatus to perform: loading a measurement protocol for at least two slices in a predetermined excitation order; determining time intervals between spatially adjacent slice excitations; determining threshold time intervals based on pulse sequence, tissue, and quality parameters; identifying and adapting intervals below threshold while maintaining excitation order; and acquiring data using the adapted pulse sequence.
The independent claims collectively cover the automatic determination and adaptation of time intervals between excitations of neighboring slices in magnetic resonance imaging, based on physical and quality parameters, to reduce crosstalk artifacts without decreasing efficiency or user flexibility, implemented as a method, an apparatus, and computer-readable instructions.
Stated Advantages
Avoidance of falsification of measurement results caused by slice crosstalk and pre-saturation effects.
Measurement time of the chosen measurement protocol is not unnecessarily increased, preserving efficiency.
Users are not restricted in their choice of slices to be excited, maintaining flexibility.
Automatic and explicit adaptation of time intervals allows artifact-free data acquisition without requiring detailed user knowledge.
Minimal intervention into the pulse sequence is sufficient (e.g., insertion of wait times), avoiding complex recalculations or re-sorting iterations.
Documented Applications
Acquisition of MR data from anatomical examination regions such as head, heart, liver, joints, or whole body with slice-selective excitation in multi-slice magnetic resonance imaging.
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