) button.
This will open the
Image Info dialog.
Fslview is able to display DTI images in a number of ways. To open a DTI image follow the same procedure as described in the image opening tutorial and load a DTI image into Fslview.
DTI image files have a very similar construction to functional image files
therefore when the image is loaded it may be interpretted as a
multi-volume functional image. To ensure that the image is viewed in
DTI Mode select the image in the
Overlay Listview and press the
Image Info() button.
This will open the
Image Info dialog.
Using the DTI Display Combo box change the value from None to Lines or RGB. When Lines is set the DTI vectors are expressed by the direction of many small lines. When RGB is set the DTI vectors are expressed by colours where Red, Green and Blue represent the x,y and z axis respectively. (The usual convention with the head is that the x axis goes from ear to ear, the y axis goes from the back of the head to the nose and the z axis goes from the neck to the top of the head.) Colours such as purple are mixes of red and blue and therefore express vectors that have both x and z components.
When DTI Display is set to RGB the DTI image can be modulated with its anisotropy image. To do this, load the anisotropy image into the Fslview application and then select this image in the Modulation combo box on the Image Info dialog.
The DTI image will now be modulated by the anisotropy image. Where anisotropy values are very low the DTI image will appear more transparent. Where the anisotropy are very high the DTI image will appear more opaque. When the DTI image is highlighted in the Overlay Listview the transparency slider will split into 2 parts. The left hand slider controls the overall transparency. The right hand slider controls the amount of transparency change caused by the modulation. If the right hand slider is set to the furthest point on the right then the modulation will have no effect at all.
The DTI image will be more easily seen if the ansiotropy is set to Invisible. This is done via the controls on the Overlay Listview.