Abstract
In dual-energy CT (DECT), two different x-ray spectra are used to acquire two image
datasets of the same region, to allow the analysis of energy-dependent changes in
the attenuation of different materials. Each type of material demonstrates a relatively
specific change in attenuation between images obtained with a high-energy spectrum
and those obtained with a low-energy spectrum. Based on the relatively specific change
in attenuation with two different energies, material composition information can be
obtained to allow tissue characterization. The DECT ability of material differentiation
allows bone removal in various CT angiography studies and bone marrow edema depiction,
while with material optimization, metal artefacts can be significantly reduced to
almost nil. DECT allows material separation to differentiate uric acid crystals from
calcium to determine the composition of urinary calculi and to diagnose gout. Using
the DECT ability of material decomposition, iodine maps can be generated, which are
useful in the evaluation of any enhancing lesion in the body without the need to obtain
a plain scan and allow perfusion maps to be created in cases of pulmonary thromboembolism.
Keywords
Dual energy CT - iodine map - material - metal artefact - uric acid
