%0 Book Section %B Medical Imaging 2002: Visualization, Image-Guided Procedures, and Display %D 2002 %T Virtual dissection of the colon: technique and first experiments with artificial and cadaveric phantoms %A Emese Balogh %A Erich Sorantin %A László Gábor Nyúl %A Kálmán Palágyi %A Attila Kuba %A Georg Werkgartner %A Ekke Spuller %E Seong Ki Mun %X Virtual dissection refers to a display technique for polypdetection, where the colon is digitally straightened and then flattened using multirow detector Computed Tomograph (CT) images. As compared to virtual colonoscopy where polyps may be hidden from view behind the folds, the unravelled colon is more suitable for polyp detection, because the entire inner surface of the colon is displayed in a single view. The method was tested both on artificial and cadaveric phantoms. All polyps could be recognized on both phantoms. This technique for virtual dissection requires only a minimum of operator interaction. %B Medical Imaging 2002: Visualization, Image-Guided Procedures, and Display %I SPIE %C Bellingham; Washington %P 713 - 721 %8 2002/// %G eng %0 Book Section %B Medical Imaging 2000: Image Display and Visualization %D 2000 %T Standardizing the MR image intensity scales: making MR intensities have tissue-specific meaning %A László Gábor Nyúl %A Jayaram K Udupa %E Seong Ki Mun %X One of the major drawbacks of Magnetic Resonance Imaging (MRI)has been the lack of a standard and quantifiable interpretation of image intensities. Unlike in other modalities such as x-ray computerized tomography, MR images taken for the same patient on the same scanner at different times may appear different from each other due to a variety of scanner-dependent variations, and therefore, the absolute intensity values do not have a fixed meaning. We have devised a two-step method wherein all images can be transformed in such a way that for the same protocol and body region, in the transformed images similar intensities will have similar tissue meaning. Standardized images can be displayed with fixed windows without the need of per case adjustment. More importantly, extraction of quantitative information with fixed windows without the need of per case adjustment. More importantly, extraction of quantitative information about healthy organs or about abnormalities can be considerably simplified. This paper introduces and compares new variants of this standardizing method that can help to overcome some of the problems with the original method. %B Medical Imaging 2000: Image Display and Visualization %I SPIE %C Bellingham; Washington %P 496 - 504 %8 2000/// %G eng %0 Book Section %B Medical Imaging 1999: Image Display %D 1999 %T Approach to standardizing MR image intensity scale %A László Gábor Nyúl %A Jayaram K Udupa %E Seong Ki Mun %E Yongmin Kim %X Despite the many advantages of MR images, they lack a standardimage intensity scale. MR image intensity ranges and the meaning of intensity values vary even for the same protocol (P) and the same body region (D). This causes many difficulties in image display and analysis. We propose a two-step method for standardizing the intensity scale in such a way that for the same P and D, similar intensities will have similar meanings. In the first step, the parameters of the standardizing transformation are 'learned' from an image set. In the second step, for each MR study, these parameters are used to map their histogram into the standardized histogram. The method was tested quantitatively on 90 whole brain FSE T2, PD and T1 studies of MS patients and qualitatively on several other SE PD, T2 and SPGR studies of the grain and foot. Measurements using mean squared difference showed that the standardized image intensities have statistically significantly more consistent range and meaning than the originals. Fixed windows can be established for standardized imags and used for display without the need of per case adjustment. Preliminary results also indicate that the method facilitates improving the degree of automation of image segmentation. %B Medical Imaging 1999: Image Display %I SPIE %C Bellingham; Washington %P 595 - 603 %8 1999/// %G eng