Radiologists feel virtual organs with 3D mouse

20 February 2008

Researchers at Uppsala University have developed a method of analysing images of organs and 'feeling' the resulting virtual organs with a 3D mouse to determine their volume.

Computerized image analysis can be used to determine the size of organs like the liver, or to construct three-dimensional models of organs when surgery or radiation treatment is being planned.

The quality of these images often varies, which makes it difficult for the computer to find the relevant information fully automatically. It is therefore common to use interactive methods in which doctors themselves mark the areas of interest in the image and then let the computer do the rest of the work based on this information.

Erik Vidholm, at the Center for Image Analysis at Uppsala University, has taken part in the development of such interactive methods where the mouse and keyboard are replaced by a 'haptic' pen-like three-dimensional mouse that enables the user to feel the virtual organs. Computer models are adapted to the images of organs and can then be used to measure the volume of the organ, for example, or to calculate changes in shape and migrations.

Erik Vidholm at Uppsala University working with the haptic pen at the specially constructed workstation that can show stereo graphics. Photo: Kristin Norell

Adaptation of a computer model to an image of a liver.
With the aid of the adapted model it is possible to measure
the volume of the liver, for instance, or calculate changes
in shape and migrations

“To get a greater sense of depth in the image we use stereo graphics. When the models are to be adapted to the images, this is done partly automatically on the basis of the content of the image and partly with the input of the user wielding the haptic pen,” he explains.

Erik Vidholm has also developed a method for rapidly visualizing complex image volumes with the aid of modern computer graphics cards. This technology has been used as a component in the development of a method for more readily discovering breast cancer.

Most of these methods have been assembled in a software package that can be freely downloaded via the Internet so that other researchers in medical image analysis can benefit from them. The package is available at:

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