The purpose of the MRI DWI Parameters tool is to load gradient vector information for diffusion weighted MR images which are not contained in the image data. This information is required for the calculation of diffusion maps and diffusion tensors. When the series is saved as a DICOM object after using the tool, the gradient information is stored together with the images.
Several encoding types are supported and can be chosen from the Gradients and B-Values file selection:
▪Camino b-vector scheme: Text file containing four columns of data: x, y, and z coordinates of b-vectors and a b-value (last column) in s/m2.
▪DSI Studio b-table: Text file containing four columns of data: b-value in s/mm2, then x, y, and z coordinates of b-vectors.
▪FSL b-vector: Text file containing b-vector coordinates in three rows: x, y, and z values respectively. As PMOD does not support b-value files as a separate input you may add the b-values from b-value file as a fourth row in s/mm2.
▪DTI parameter file: Text file (.dpf) from DTI Studio containing b-vector directions and b-values.
▪Gradient directions file: General option for text files with three to five columns. Three-column files are assumed to contain x, y, and z coordinates of b-vectors. Four-column files are assumed to have b-values in the last column. Five-column files are assumed to have gradient indexes in the first column. This option accepts gradient tables exported from the PMOD Info dialog window. B-values are in s/mm2.
▪ParaVision: For loading b-vectors directions and b-values from a Bruker ParaVision Parameter List file.
▪NRRD header: For loading b-vectors directions and b-values from the DWMRI section of a NRRD format header file.
▪PMOD DB: For loading b-vector directions and b-values from the gradient table files stored to a PMOD database. The data in the file is arranged in five columns as in Gradient directions file. A comment line starts with #.