MOLLI Registration

This application serves for MOLLI sequence registration. The method uses distance maps of segmented myocardia to estimate the displacement between two images. Therefore the first step necessary to obtain registered images is a segmentation.

Segmentation

The working window has two parts - one for each image. The image on the left part of the window will be referred as a source image, the one on the right side as a target image. When the chosen image is displayed, its brightness and contrast can be adjusted using the color scale under the image. (This change will effect only the visualization of the image).

In order to start the segmentation, it is required to set the center of initial ring, it‘s inner and outer radius. The ring should be positioned so that the myocardium lies between the outer and inner circle of the ring. These parameters can be set by clicking in the displayed image. Every time the parameters are changed, updated ring is displayed in the image.

Another parameters, that can be adjusted to improve the segmentation, are K1 and K2. These values effect the sensitivity to change of image intensity during the detection of outer and inner boundary of the myocardium. For images with higher contrast, the default value can be decreased. For images with similar intensity of myocardium and it‘s surrounding, the value should be increased. Example of such setting can be seen in the following picture.

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When the outcome of segmentation process is not sufficient, the parameters can be modified or set to zero by the ‚Reset‘ button.

Registration

When the myocardium on both source and target images are segmented, as can be seen in the following figure, the images can be registered.

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Registration (source -> target)

If more suitable, the inverse transformation can be determined.

Registration (target -> source)

The following figure shows the source image before deformation on the right and the deformed one on the left.

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