Open AccessUpdate on Multienergy CT: Physics, Principles, and Applications
Author(s) -
Prabhakar Rajiah,
Anushri Parakh,
Fernando Uliana Kay,
Dhiraj Baruah,
Avinash Kambadakone,
Shuai Leng
Publication year - 2020
Publication title -
radiographics
Language(s) - English
Resource type - Journals
eISSN - 1527-1323
pISSN - 0271-5333
DOI - 10.1148/rg.2020200038
Subject(s) - detector , medicine , dual energy , energy (signal processing) , biomedical engineering , computer science , physics , optics , pathology , bone mineral , osteoporosis , quantum mechanics
Multienergy CT involves acquisition of two or more CT measurements with distinct energy spectra. Using the differential attenuation of tissues and materials at different x-ray energies, multienergy CT allows distinction of tissues and materials beyond that possible with conventional CT. Multienergy CT technologies can operate at the source or detector level. Dual-source, rapid tube-voltage switching, and dual-layer detector CT are the most commonly used multienergy CT technologies. Most of the currently available technologies typically use two energy levels, commonly referred to as dual-energy CT . With use of two or more energy bins, photon-counting detector CT can perform multienergy CT beyond current dual-energy CT technologies. Multienergy CT postprocessing can be performed in the projection or image domain using two-material or multimaterial decomposition. The most commonly used multienergy CT images are virtual monoenergetic images (VMIs), iodine maps, virtual noncontrast (VNC) images, and uric acid images. Low-energy VMIs are used to boost contrast signal and enhance lesion conspicuity. High-energy VMIs are used to decrease some artifacts. Iodine maps are used to evaluate perfusion, characterize lesions, and evaluate response to therapy. VNC images are used to characterize lesions and save radiation dose by eliminating true noncontrast images from multiphasic acquisitions. Uric acid images are used for characterization of renal calculi and gout. Online supplemental material is available for this article. © RSNA, 2020.