def __call__(
self,
kspace: np.ndarray,
mask: np.ndarray,
target: np.ndarray,
attrs: Dict,
fname: str,
slice_num: int,
) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor, str, int, float,
torch.Tensor]:
"""
Args:
kspace: Input k-space of shape (num_coils, rows, cols) for
multi-coil data.
mask: Mask from the test dataset.
target: Target image.
attrs: Acquisition related information stored in the HDF5 object.
fname: File name.
slice_num: Serial number of the slice.
Returns:
tuple containing:
masked_kspace: k-space after applying sampling mask.
mask: The applied sampling mask
target: The target image (if applicable).
fname: File name.
slice_num: The slice index.
max_value: Maximum image value.
crop_size: The size to crop the final image.
"""
if target is not None:
target = to_tensor(target)
max_value = attrs["max"]
else:
target = torch.tensor(0)
max_value = 0.0
kspace = to_tensor(kspace)
seed = None if not self.use_seed else tuple(map(ord, fname))
acq_start = attrs["padding_left"]
acq_end = attrs["padding_right"]
crop_size = torch.tensor(
[attrs["recon_size"][0], attrs["recon_size"][1]])
if self.mask_func:
masked_kspace, mask = apply_mask(kspace, self.mask_func, seed,
(acq_start, acq_end))
else:
masked_kspace = kspace
shape = np.array(kspace.shape)
num_cols = shape[-2]
shape[:-3] = 1
mask_shape = [1] * len(shape)
mask_shape[-2] = num_cols
mask = torch.from_numpy(
mask.reshape(*mask_shape).astype(np.float32))
mask = mask.reshape(*mask_shape)
mask[:, :, :acq_start] = 0
mask[:, :, acq_end:] = 0
return (
masked_kspace,
mask.byte(),
target,
fname,
slice_num,
max_value,
crop_size,
)
def __call__(
self,
kspace: np.ndarray,
sensitivity_map: np.ndarray,
mask: np.ndarray,
eta: np.ndarray,
target: np.ndarray,
attrs: Dict,
fname: str,
slice_idx: int,
) -> Tuple[torch.Tensor, Union[Union[List, torch.Tensor], torch.Tensor],
Union[Optional[torch.Tensor], Any], Union[List, Any], Union[
Optional[torch.Tensor], Any], Union[torch.Tensor, Any], str,
int, Union[Union[List, torch.Tensor], Any], ]:
"""
Apply the data transform.
Parameters
----------
kspace: The kspace.
sensitivity_map: The sensitivity map.
mask: The mask.
eta: The initial estimation.
target: The target.
attrs: The attributes.
fname: The file name.
slice_idx: The slice number.
Returns
-------
The transformed data.
"""
kspace = to_tensor(kspace)
# This condition is necessary in case of auto estimation of sense maps.
if sensitivity_map is not None and sensitivity_map.size != 0:
sensitivity_map = to_tensor(sensitivity_map)
# Apply zero-filling on kspace
if self.kspace_zero_filling_size is not None and self.kspace_zero_filling_size not in (
"", "None"):
padding_top = np.floor_divide(
abs(int(self.kspace_zero_filling_size[0]) - kspace.shape[1]),
2)
padding_bottom = padding_top
padding_left = np.floor_divide(
abs(int(self.kspace_zero_filling_size[1]) - kspace.shape[2]),
2)
padding_right = padding_left
kspace = torch.view_as_complex(kspace)
kspace = torch.nn.functional.pad(kspace,
pad=(padding_left, padding_right,
padding_top, padding_bottom),
mode="constant",
value=0)
kspace = torch.view_as_real(kspace)
sensitivity_map = fft2(
sensitivity_map,
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
)
sensitivity_map = torch.view_as_complex(sensitivity_map)
sensitivity_map = torch.nn.functional.pad(
sensitivity_map,
pad=(padding_left, padding_right, padding_top, padding_bottom),
mode="constant",
value=0,
)
sensitivity_map = torch.view_as_real(sensitivity_map)
sensitivity_map = ifft2(
sensitivity_map,
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
)
# Initial estimation
eta = to_tensor(
eta) if eta is not None and eta.size != 0 else torch.tensor([])
# If the target is not given, we need to compute it.
if self.coil_combination_method.upper() == "RSS":
target = rss(
ifft2(
kspace,
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
),
dim=self.coil_dim,
)
elif self.coil_combination_method.upper() == "SENSE":
if sensitivity_map is not None and sensitivity_map.size != 0:
target = sense(
ifft2(
kspace,
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
),
sensitivity_map,
dim=self.coil_dim,
)
elif target is not None and target.size != 0:
target = to_tensor(target)
elif "target" in attrs or "target_rss" in attrs:
target = torch.tensor(attrs["target"])
else:
raise ValueError("No target found")
target = torch.view_as_complex(target)
target = torch.abs(target / torch.max(torch.abs(target)))
seed = tuple(map(ord, fname)) if self.use_seed else None
acq_start = attrs["padding_left"] if "padding_left" in attrs else 0
acq_end = attrs["padding_right"] if "padding_left" in attrs else 0
# This should be outside the condition because it needs to be returned in the end, even if cropping is off.
# crop_size = torch.tensor([attrs["recon_size"][0], attrs["recon_size"][1]])
crop_size = target.shape
if self.crop_size is not None and self.crop_size not in ("", "None"):
# Check for smallest size against the target shape.
h = min(int(self.crop_size[0]), target.shape[0])
w = min(int(self.crop_size[1]), target.shape[1])
# Check for smallest size against the stored recon shape in metadata.
if crop_size[0] != 0:
h = h if h <= crop_size[0] else crop_size[0]
if crop_size[1] != 0:
w = w if w <= crop_size[1] else crop_size[1]
self.crop_size = (int(h), int(w))
target = center_crop(target, self.crop_size)
if sensitivity_map is not None and sensitivity_map.size != 0:
sensitivity_map = (ifft2(
complex_center_crop(
fft2(
sensitivity_map,
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
),
self.crop_size,
),
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
) if self.kspace_crop else complex_center_crop(
sensitivity_map, self.crop_size))
if eta is not None and eta.ndim > 2:
eta = (ifft2(
complex_center_crop(
fft2(
eta,
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
),
self.crop_size,
),
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
) if self.kspace_crop else complex_center_crop(
eta, self.crop_size))
# Cropping before masking will maintain the shape of original kspace intact for masking.
if self.crop_size is not None and self.crop_size not in (
"", "None") and self.crop_before_masking:
kspace = (complex_center_crop(kspace, self.crop_size)
if self.kspace_crop else fft2(
complex_center_crop(
ifft2(
kspace,
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
),
self.crop_size,
),
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
))
# Undersample kspace if undersampling is enabled.
if self.mask_func is None:
masked_kspace = kspace
acc = torch.tensor([np.around(mask.size / mask.sum())
]) if mask is not None else torch.tensor([1])
if mask is None:
mask = torch.ones(
[masked_kspace.shape[-3], masked_kspace.shape[-2]],
dtype=torch.float32 # type: ignore
)
else:
mask = torch.from_numpy(mask)
if mask.shape[0] == masked_kspace.shape[2]: # type: ignore
mask = mask.permute(1, 0)
elif mask.shape[0] != masked_kspace.shape[1]: # type: ignore
mask = torch.ones(
[masked_kspace.shape[-3], masked_kspace.shape[-2]],
dtype=torch.float32 # type: ignore
)
if mask.ndim == 1:
mask = np.expand_dims(mask, axis=0)
if mask.shape[-2] == 1: # 1D mask
mask = torch.from_numpy(mask).unsqueeze(0).unsqueeze(-1)
else: # 2D mask
# Crop loaded mask.
if self.crop_size is not None and self.crop_size not in (
"", "None"):
mask = center_crop(mask, self.crop_size)
mask = mask.unsqueeze(0).unsqueeze(-1)
if self.shift_mask:
mask = torch.fft.fftshift(mask, dim=[-3, -2])
masked_kspace = masked_kspace * mask
mask = mask.byte()
elif isinstance(self.mask_func, list):
masked_kspaces = []
masks = []
accs = []
for m in self.mask_func:
_masked_kspace, _mask, _acc = apply_mask(
kspace,
m,
seed,
(acq_start, acq_end),
shift=self.shift_mask,
half_scan_percentage=self.half_scan_percentage,
center_scale=self.mask_center_scale,
)
masked_kspaces.append(_masked_kspace)
masks.append(_mask.byte())
accs.append(_acc)
masked_kspace = masked_kspaces
mask = masks
acc = accs
else:
masked_kspace, mask, acc = apply_mask(
kspace,
self.mask_func[0], # type: ignore
seed,
(acq_start, acq_end),
shift=self.shift_mask,
half_scan_percentage=self.half_scan_percentage,
center_scale=self.mask_center_scale,
)
mask = mask.byte()
# Cropping after masking.
if self.crop_size is not None and self.crop_size not in (
"", "None") and not self.crop_before_masking:
masked_kspace = (complex_center_crop(masked_kspace, self.crop_size)
if self.kspace_crop else fft2(
complex_center_crop(
ifft2(
masked_kspace,
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
),
self.crop_size,
),
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
))
mask = center_crop(mask.squeeze(-1), self.crop_size).unsqueeze(-1)
# Normalize by the max value.
if self.normalize_inputs:
if isinstance(self.mask_func, list):
masked_kspaces = []
for y in masked_kspace:
if self.fft_normalization in ("orthogonal",
"orthogonal_norm_only",
"ortho"):
imspace = ifft2(
y,
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
)
imspace = imspace / torch.max(torch.abs(imspace))
masked_kspaces.append(
fft2(
imspace,
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
))
elif self.fft_normalization == "fft_norm":
imspace = ifft2(
y,
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
)
masked_kspaces.append(
fft2(
imspace,
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
))
elif self.fft_normalization == "backward":
imspace = ifft2(y,
centered=self.fft_centered,
normalization="backward",
spatial_dims=self.spatial_dims)
masked_kspaces.append(
fft2(
imspace,
centered=self.fft_centered,
normalization="backward",
spatial_dims=self.spatial_dims,
))
else:
imspace = torch.fft.ifftn(torch.view_as_complex(y),
dim=[-2, -1],
norm=None)
imspace = imspace / torch.max(torch.abs(imspace))
masked_kspaces.append(
torch.view_as_real(
torch.fft.fftn(imspace,
dim=[-2, -1],
norm=None)))
masked_kspace = masked_kspaces
elif self.fft_normalization in ("orthogonal",
"orthogonal_norm_only", "ortho"):
imspace = ifft2(
masked_kspace,
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
)
imspace = imspace / torch.max(torch.abs(imspace))
masked_kspace = fft2(
imspace,
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
)
elif self.fft_normalization == "fft_norm":
masked_kspace = fft2(
ifft2(
masked_kspace,
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
),
centered=self.fft_centered,
normalization=self.fft_normalization,
spatial_dims=self.spatial_dims,
)
elif self.fft_normalization == "backward":
masked_kspace = fft2(
ifft2(
masked_kspace,
centered=self.fft_centered,
normalization="backward",
spatial_dims=self.spatial_dims,
),
centered=self.fft_centered,
normalization="backward",
spatial_dims=self.spatial_dims,
)
else:
imspace = torch.fft.ifftn(torch.view_as_complex(masked_kspace),
dim=[-2, -1],
norm=None)
imspace = imspace / torch.max(torch.abs(imspace))
masked_kspace = torch.view_as_real(
torch.fft.fftn(imspace, dim=[-2, -1], norm=None))
if sensitivity_map.size != 0:
sensitivity_map = sensitivity_map / torch.max(
torch.abs(sensitivity_map))
if eta.size != 0 and eta.ndim > 2:
eta = eta / torch.max(torch.abs(eta))
target = target / torch.max(torch.abs(target))
return kspace, masked_kspace, sensitivity_map, mask, eta, target, fname, slice_idx, acc
