Morphing radiologic images: applications on a desktop computer.

Objective: Morphing is an image processing technology that transforms one image into another by generating a series of intermediate synthetic images. The ability to perform morphing, once restricted to high-end graphics workstations, is now widely available for desktop computers. We investigated the potential use of morphing for displaying radiographic images.

Materials And Methods: Morphing was performed with commercially available software (Morph 2.5; Gryphon Software, San Diego, CA) on a Macintosh (Apple Computer, Cupertino, CA) computer. Images from 26 patients with serial radiologic studies were selected, digitized, and morphed. Key points and key surfaces were identified on the images to improve the quality of the morph movie, a process that took approximately 15 min. The images were then morphed into a continuous Quick Time (Apple) movie lasting 5-7 sec. When a sequence contained more than two images, a single movie incorporating all the images was created. The intervals between segments of the movie were made proportional to the actual time elapsed between the images. Images obtained with different techniques (positron emission tomography and MR imaging) were also morphed. Three observers judged the quality of the morph movies as satisfactory, good, or excellent.

Results: Twenty of the 26 movies were judged to be of good or excellent quality. The movie format allowed the rapid display of multiple images in a concise 5- 7-sec time frame. Moreover, the movie allowed the recognition of several simultaneous processes more easily than was possible with static images. Morphing two images of the same anatomic site using different techniques (MR imaging and positron emission tomography) proved to be a simple method of superimposing images.

Conclusion: Morphing is a readily available and easily learned technique for displaying serial studies. The movie format is a more interesting, intuitive, and concise summary of events than can be provided by serial static images. Morphing may be useful for displaying large numbers of serial images in a short time for occasions such as clinical conferences or teaching purposes.