Data Importation

The first step is to import your own data into the DTI Track module. We developped a specific file format to handle in an easy way DT-MRI sequences. This format is called a ``DTI Study'' (extension .dts), and stores in a human readable way all information regarding your data: number of images, images, gradient sequence, parameters used for the processing, saved tensor and fiber files, etc. You only need to import your data once, and then you will be able to reuse it without going through the importation process again.

To import your DTI dataset, click on the ``new .dts'' icon and a wizard will popup to guide you through the process.

Figure 3.2: DTI importer wizard. This wizard guides you to import your data before studying a DTI analysis. On the left is shown the welcoming screen while on the right is shown the importation screen where are written the names of the DWI and their associated gradients. All this information will be stored in a DTI-study.

Click Next to proceed to the import screen (Fig. 3.2, right).

Click on the ``Open'' button to load the DTI sequence (Fig. 3.2, right). Select all volume images that compose your dataset. The images will be sorted in alpha order afterwards. Then click on the ``Load Sequence'' button to load the gradients used for the acquisition. There has to be the same number of gradients as the number of volume images. Note that the gradient sequence must match the list of images after being sorted: the first image corresponds to the first gradient in the text list, etc (see appendix for details on the gradient list file). Also note that you have to put a B0 image at the top. The software can only support one B0 image for the moment. Please do not import several B0 images. You can also give additional information to your study. For instance you can set the name of the patient, or specify a registration matrix between the DWI and any other image to map the reconstructed fibers onto this new image (such as the T1 image). For more details on the registration matrix see appendix.

Figure 3.3: The last step of the importer wizard. This screen helps you to obtain the radiologic conventions. You can flip the image around the xyz axes in order to match the conventions, click next to validate your choice. All images (DWI, T1) will be flipped to respect the radiologic conventions.

On the next screen you will be able to change orientation of your DWI regarding radiologic conventions (see Fig. 3.3). Click on Flip R-L, Flip A-P, or Flip I-S to flip the volume respectively around the Right-Left axis, the Anterior-Posterior axis or the Inferior-Superior axis. Once the radiologic convention are obtained, click next to validate your choice.

The last screen of this import wizard shows you a summary of the DTI-study. Please check if the information is correct. ``Axes Flipped'' show the axes flipped in order to match radiologic conventions, respectively the Righ-Left axis, the Anterior-Posterior axis, and Inferiro-Superior axis (1 means that the axis has been flipped). You can now save the DTI-study with the ``save'' button. This file has to be stored in the same folder where the DWI are (it will be done automatically). You can now click finish. Your DTI-study has been succesfully created.

At any time you can save any change of parameters or DTI results (tensors, fibers and fiber bundles) into the DTI-study file by clicking ``save .dts'' button. You will be able to retrieve all your information directly by openning the DTI-study.

If you want to move the DTI-study file (extension .dts) to another folder, make sure you also move tensors (sudyname_tensors.inr.gz), fibers (studyname_fibers.fib), bundles ( *.fib) and all the DWI with it, otherwise you will not be able to open the study correctly.