Patent ID: 11867786
Assignee: UMC UTRECHT HOLDING B.V.
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A method for determining a spatial distribution of at least one tissue parameter within a sample based on a time domain magnetic resonance, TDMR, signal emitted from the sample after excitation of the sample according to an applied pulse sequence, the method comprising:
i) determining a TDMR signal model to approximate the emitted time domain magnetic resonance signal, wherein the TDMR signal model is configured to be dependent on TDMR signal model parameters comprising:
the spatial distribution of the at least one tissue parameter within the sample; and
the applied pulse sequence;

ii) estimating an initial set of TDMR signal model parameters;
iii) determining a residual vector being representative for a difference between the emitted TDMR signal and the TDMR signal model, based on the initial set of TDMR signal model parameters as an input;
iv) determining an updated set of TDMR signal model parameters by
v) calculating a gradient of the residual vector;
vi) calculating a sparse Hessian of the TDMR signal model, the calculated sparse Hessian having a sparsity pattern that is calculated using the applied pulse sequence, thereby knowing in advance the coefficients of the sparse Hessian to be calculated; and
vii) updating the initial set of TDMR signal model parameters based on the calculated gradient and calculated Hessian;
viii) repeating steps iii), iv), v), vi) and vii) using the updated set of TDMR signal model parameters as the input until the difference between the emitted TDMR signal and the TDMR signal model is smaller than a predefined threshold or until a predetermined number of repetitions is completed, thereby obtaining a final updated set of TDMR signal model parameters; and
ix) extracting from the final updated set of TDMR signal model parameters the spatial distribution of the at least one tissue parameter.