Method for Homogenizing a B1 Transmission Field

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This patent describes a method for homogenizing the B1 transmission field used in magnetic resonance imaging (MRI). By using either measured data from a physical phantom or simulated data, the invention optimizes the excitation phases and amplitudes of the transmission coil's elements to minimize field inhomogeneity. This process does not require patient-specific sensitivity maps, can be applied both in low-field and high-field MRI systems, and can potentially improve image quality across different MRI scenarios.

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• Enhancing MRI image quality by correcting B1 field inhomogeneities in both clinical and research MRI scanners.
• Pre-calibration of MRI systems before scanning, reducing the need for patient-specific calibration.
• Optimization of transmit coil settings in high-field MRI where inhomogeneities are most problematic.
• Imaging of human organs (e.g., the brain) with improved diagnostic reliability by reducing artifacts caused by field inhomogeneity.
• Integration into MRI system software for automated B1 shimming routines.

BenefitsContent extracted from patent full text and abstract with AI.

• Reduces or eliminates the need to acquire patient-specific calibration data, saving time per MRI examination.
• Improves the uniformity of the MRI excitation field, leading to better and more reliable image quality.
• Applicable to both low-field and high-field MRI, making it suitable for state-of-the-art imaging equipment.
• Can be implemented using either measured or simulated phantom data, allowing for flexible adaptation based on available resources.
• Considers both the transmit and receive field characteristics for optimal homogenization, improving diagnostic confidence.

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Patent Abstract

The invention relates to a method for homogenising a B1-transmission field, comprising the following steps: a) complex-valued image intensities are measured, if using a phantom, or calculated if simulating a phantom, for each transmission element of the transmission coil, b) this measured or calculated complex-valued image intensity is multiplied, for each transmission channel, by the excitation phase and/or amplitude, c) the individual complex-valued image intensities obtained from step b) are added together to obtain a total image intensity, d) the quality of homogenisation C is ascertained according to formula (1) from the determined real total image intensity by weighting individual characteristic values, where C = measurement of the quality of the B1-transmission field (B1 +), λ1 and λ2 = weighting parameters, std() = standard deviation of the real image intensity I, mean() = mean value of the real image intensity I, (ROI1), (ROI2) = (1) in which the object to be examined is or is at least partially located and the adjoining region (2) which is characterised by low real image intensities, e) C is minimised using calculation methods for extreme value calculation, and f) the transmission phases and/or transmission amplitudes determined in step e) are set as parameters for controlling the B1-transmission field (B1 +).