Special Edition: Spectral CT, March 2015
Special Editors: G. Wang, A. Butler, H. Yu, M. Campbell
IEEE Trans Med Imaging, vol. 34, issue 3, March 2015
Now, x-ray CT gains a spectral dimension, and sees colorful opportunities. This special issue on spectral CT includes 15 high-quality papers from leading groups around the world. These papers are briefly summarized in the editorial for your convenience.
It is emphasized that spectral CT could enable CT for better functional and even molecular imaging. Current molecular imaging modalities, especially PET, SPECT, MRI, and optical imaging, have gone a long way towards peeking into biological processes at the molecular and cellular levels, but they are still far from capturing the whole picture. PET and SPECT, although sensitive, are slow, non-specific, and require radioactive tracers. MRI has great soft tissue contrast (proton density, T1, T2, flow, chemical shift, elasticity, and temperature) but long imaging time is needed for high spatial resolution, and it cannot be used for patients with claustrophobia, pacemakers or aneurysm clips. While metabolites have characteristic peaks of involved nuclei, MRI is generally not quantitative for complex or dynamic parts of the body. Optical molecular tomography is sensitive and specific but its limited penetration depth prevents its use for most clinical tasks. Now, given chemically-specific and/or functionalized contrast agents that are already available or still under development, spectral CT with photon-counting detectors promises to complement existing modalities with functional and molecular information that are not possible from conventional CT.