Contrast enhancement in emission tomography by way of synergistic PET/CT image combination
Computer Methods and Programs in Biomedicine. 2008-06-01; 90(3): 191-201
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1. Comput Methods Programs Biomed. 2008 Jun;90(3):191-201. doi:
10.1016/j.cmpb.2007.12.009. Epub 2008 Mar 4.
Contrast enhancement in emission tomography by way of synergistic PET/CT image
Boussion N(1), Hatt M, Lamare F, Rest CC, Visvikis D.
(1)INSERM, U650, Laboratoire du traitement de l’information médicale , CHU
Morvan, 29609 Brest, France.
The display of image fusion is well accepted as a powerful tool in visual image
analysis and comparison. In clinical practice, this is a mandatory step when
studying images from a dual PET/CT scanner. However, the display methods that are
implemented on most workstations simply show both images side by side, in
separate and synchronized windows. Sometimes images are presented superimposed in
a single window, preventing the user from doing quantitative analysis. In this
article a new image fusion scheme is presented, allowing performing quantitative
analysis directly on the fused images.METHODS: The objective is to preserve the
functional information provided by PET while incorporating details of higher
resolution from the CT image. The process relies on a discrete wavelet-based
image merging: both images are decomposed into successive details layers by using
the “à trous” transform. This algorithm performs wavelet decomposition of images
and provides coarser and coarser spatial resolution versions of them. The
high-spatial frequencies of the CT, or details, can be easily obtained at any
level of resolution. A simple model is then inferred to compute the lacking
details of the PET scan from the high frequency detail layers of the CT. These
details are then incorporated in the PET image on a voxel-to-voxel basis, giving
the fused PET/CT image.
RESULTS: Aside from the expected visual enhancement, quantitative comparison of
initial PET and CT images with fused images was performed in 12 patients. The
obtained results were in accordance with the objectives of the study, in the
sense that the organs’ mean intensity in PET was preserved in the fused image.
CONCLUSION: This alternative approach to PET/CT fusion display should be of
interest for people interested in a more quantitative aspect of image fusion. The
proposed method is actually complementary to more classical visualization tools.
PMID: 18291555 [Indexed for MEDLINE]