Absolute Receive Sensitivity Maps for MRI Shading Correction

The patent performs preliminary calibration to determine transmit sensitivity maps (B1+) before the actual imaging process. This preliminary measurement allows the system to pre-distort RF pulses and compensate for transmit field inhomogeneities, resolving the contradiction by preparing the necessary correction data in advance rather than requiring complex real-time adjustments during imaging

The patent uses measured transmit sensitivity maps to create feedback loops where the determined B1+ distributions are used to pre-distort subsequent RF pulses. This feedback mechanism allows the system to automatically compensate for transmit field inhomogeneities without requiring manual adjustment or increased hardware complexity

The patent performs preliminary determination of absolute reception sensitivity maps (B1-) using measured subject parameters and coil geometry. This preliminary characterization of receive sensitivity allows the system to compensate for shading artifacts during image reconstruction while maintaining relatively simple processing algorithms, thus resolving the contradiction between processing simplicity and image quality

The patent transforms the approach from using relative sensitivity ratios to using absolute sensitivity values derived from electromagnetic parameter measurements. By changing the parameter basis from relative to absolute measurements incorporating tissue conductivity and permittivity, the system achieves accurate shading correction without proportionally increasing processing complexity

The patent uses a unified electromagnetic simulation approach that simultaneously determines both transmit (B1+) and receive (B1-) sensitivity maps from the same set of measured electromagnetic parameters and coil geometry data. This multi-functional approach allows the system to obtain both sensitivity maps in a single measurement and simulation process, resolving the contradiction by eliminating the need for separate measurement sequences

The patent uses numerical electromagnetic simulation to create virtual models of the RF field distributions based on measured subject parameters. Instead of performing separate physical measurements for each sensitivity map, the system creates computational copies of the electromagnetic fields through simulation, significantly reducing measurement time while maintaining accuracy

The patent measures and incorporates subject-specific electromagnetic parameters (conductivity σ and permittivity ε) into the imaging process. By using these measured parameters to simulate and correct for dielectric effects at high field strengths, the system maintains the signal-to-noise ratio benefits of high field while compensating for the associated shading artifacts through parameter-based correction

The patent replaces physical hardware modifications with computational correction methods. Instead of modifying coil designs or adding physical shielding to address dielectric effects, the system uses numerical simulation and algorithmic correction based on measured electromagnetic parameters, effectively substituting computational processing for mechanical solutions