MRIStackedNUFFTGPU

class mrinufft.operators.stacked.MRIStackedNUFFTGPU(samples, shape, smaps=None, n_coils=1, n_batchs=1, n_trans=1, z_index='auto', squeeze_dims=False, smaps_cached=False, density=False, backend='cufinufft', **kwargs)

Bases: MRIStackedNUFFT

Stacked NUFFT Operator for MRI using GPU only backend.

This requires cufinufft to be installed.

Parameters:

• samples (array-like) – Sample locations in a 2D kspace

• shape (tuple) – Shape of the image.

• z_index (array-like) – Cartesian z index of masked plan. if “auto” the z_index is computed from the samples, if they are 3D, using the last coordinate.

• smaps (array-like) – Sensitivity maps.

• n_coils (int) – Number of coils.

• n_batchs (int) – Number of batchs.

• **kwargs (dict) – Additional arguments to pass to the backend.

Methods

__init__
adj_op	Adjoint operator.
cg	Conjugate Gradient method to solve the inverse problem.
check_shape	Validate the shapes of the image or k-space data against operator shapes.
compute_density	Compute the density compensation weights and set it.
compute_smaps	Compute the sensitivity maps and set it.
data_consistency	Compute the gradient data consistency.
get_lipschitz_cst	Return the Lipschitz constant of the operator.
make_autograd	Make a new Operator with autodiff support.
op	Forward operator.
with_autograd	Return a Fourier operator with autograd capabilities.
with_off_resonance_correction	Return a new operator with Off Resonnance Correction.

Attributes

autograd_available
available
backend
cpx_dtype	Return complex floating precision of the operator.
density	Density compensation of the operator.
dtype	Return dtype.
interfaces
n_batchs	Number of coils for the operator.
n_coils	Number of coils for the operator.
n_samples	Return number of samples.
ndim	Number of dimensions in image space of the operator.
norm_factor	Norm factor of the operator.
samples	Return samples as a N_slice x N_samples x 3 array.
shape	Shape of the image space of the operator.
smaps	Sensitivity maps of the operator.
uses_density	Return True if the operator uses density compensation.
uses_sense	Return True if the operator uses sensitivity maps.

property norm_factor

Norm factor of the operator.

static _fftz(data)

Apply FFT on z-axis.

static _ifftz(data)

Apply IFFT on z-axis.

op(data, ksp=None)

Forward operator.

Note

This function uses numpy for all CPU arrays, and cupy for all on-gpu array. It will convert all its array argument to the respective array library. The outputs will be converted back to the original array module and device.

adj_op(coeffs, img=None)

Adjoint operator.

Note

This function uses numpy for all CPU arrays, and cupy for all on-gpu array. It will convert all its array argument to the respective array library. The outputs will be converted back to the original array module and device.

get_lipschitz_cst(max_iter=10, **kwargs)

Return the Lipschitz constant of the operator.

Parameters:

• max_iter (int) – Number of iteration to perform to estimate the Lipschitz constant.

• kwargs – Extra kwargs for the cufinufft operator.

Returns:

Lipschitz constant of the operator.

Return type:

float