Stradview uses the Stradwin data file format to store additional information about loaded image data. This file has the suffix '.sw' and contains all the relevant settings and parameters associated with the image data. It also contains a reference to the location of the image data which, for DICOM or image formats, is never changed. When you load a file, Stradview also loads the referenced data and temporarily changes the relevant display settings and parameters to match the settings from the file. These parameters revert to their previous values when you close the file.
Detailed information on the format of Stradwin data, settings and configuration files can be found here.
Also see below for details on exporting image data, specific frames and resliced data.
A data set which is a regular 3D array can be exported to either NIfTI or NRRD data format. Both options can either be compressed or raw: the raw version is much quicker to read and write, though can take up much more space. These formats are widely recognised by other medical imaging software. However, such data does not include any objects or landmarks you have created in Stradview: if you want to export these to other software, you will need to do this separately, using the draw and landmarks task pages.
If the data set does not have parallel frames, or the frames are not regularly spaced, then you can use export resliced data first to create a regular 3D Stradwin data set; then load this new data set back into Stradview; then you can export this data to a new format.
If you want to convert the data to a sequence of images, then export specific frames instead.
This feature can be used either to export frames in one of a number of common image formats, or to create a new Stradwin data file with a reduced set of frames. The latter is useful if the data contains frames which are beyond the imaged object, or if you want to 'thin' the whole data set to reduce the size and resolution.
First enter the range of frames that you wish to export. This is a text field which operates in a similar manner to entering a range of pages when printing a document. You can specify individual frames, ranges of frames, ranges of frames with a defined number to skip, or any combination of these. The default is to export the currently displayed frame.
Stradview then prompts for a file name and file type to save the data to. If an image format is selected, then the frames are saved as individual images to files in this format. If more than one frame has been selected, the file name used for each frame is appended with the number of the original frame. Hence a frame range of '1-2' and a file name of 'bscan.jpeg' will cause the data to be saved to files 'bscan1.jpeg' and 'bscan2.jpeg'.
If the selected format is 'Stradwin file', then the selected frames and any corresponding landmarks and object contours, as well as all associated configuration information, will be saved to a Stradwin file. In this case, the new Stradwin file is also loaded into Stradview so that it becomes the current data set. If the existing data has not already been saved, Stradview will warn that it may be lost before completing the export.
Stradwin data files only contain the original data, which is not necessarily regularly spaced nor parallel. The visualisation tools in Stradview are optimised to work directly from such data, in order to maintain the highest possible resolution in every image. Outlining of objects in Stradview is always performed in the original image frames, since the many artefacts common in medical images are much better understood in these frames.
By contrast, most general visualisation tools expect data to be arranged in a regularly spaced grid. This export option is provided to enable non-regular Stradview data to be visualised in such tools. However, it should be noted that visualisations from regular resliced data (other than those exactly aligned with the exported grid) will not be as precise as those available within Stradview, and some care should be exercised when outlining objects in such data.
Regular 3D arrays are exported aligned to the current reslice or orthogonal visualisation, whichever is selected. In the case of orthogonal visualisation, the alignment is with respect to the left of the two reslices. The width and height of each slice of data will be exactly the same as in the displayed reslice, and the number of slices will be chosen to cover the full extent of the 3D data. The data will be exported in the original position sensor coordinates. Using the reslice visualisation, and setting the location with the 'Locate for minimum voxels' button, will ensure that all the data is exported in an orientation which minimises the size of the output data. If you want to keep the current reslice orientation but limit the output data range to a minimum, then use the 'Auto centre and size' button instead.
First select the resolution for the exported data. This can either be chosen as some integer multiple of the current image pixel width, or alternatively fixed slice separations of 1mm to 20mm can be selected. In each case, the approximate size of the exported data file is displayed.
Stradview then prompts for a file name to save the data to. This is in Stradwin format, where each new 'frame' actually corresponds to one slice from the voxelised data. The coordinate system is preserved, so a landmark placed on the original data will still appear in the same location in the voxel array data. Any current landmarks are also exported in addition to the data. If there are any current surfaces, the intersection of these surfaces with each slice is saved with the data. When the exported voxel array is re-loaded into Stradview, these will appear as new object contours.