PET/CT is a widely used dual-modality imaging technique that has been clearly shown to improve tumor
localization and hence patient outcomes. The standard means by which PET/CT images are displayed for
review is alpha-blending which results in a merge of the two images using a variable parameter, α, to select the
relative proportion of each image displayed. In this work, we present a new fusion technique based on Gram-
Schmidt spectral sharpening to display the physiological information found in the PET image along with the
anatomical details from the higher resolution CT image.
A selected color table is applied to the PET data to create a mult-channel (multiband) RGB image. This
image, up-scaled to the resolution of the CT data, along with the original PET data which represents a lower
resolution single-channel (panchromatic) image, is processed via Gram-Schmidt orthogonalization. Then, the
higher resolution CT data, modified to more closely match the PET statistics, is substituted for the first vector
of the new orthogonal set. Finally, an inverse Gram-Schmidt process restores the data and results in a new RGB
image which is the fusion of the original PET/CT data.
We show that this new image provides a clear indication of PET activity while preserving the details of the
CT image. We compare these images with alpha-blended images as well as color-based and PCA-based spectral