Quantitative CT characterization of body fluids with spectral ρZ projection method

We have performed a clinical study on the characterization of body fluids with the spectral ρZ projection algorithm. It converts dual-energy CT scans into density ρ and atomic number Z information. We provide data on a total of 56 samples of 6 different classes. Blood, gall, pus and urine, as well as mixtures of blood + pus and blood + ethylendiamintetra acetate (EDTA, a blood anti-coagulant) have been investigated. For standard measurements with 80 kV and 140 kV tube voltages we encounter larger overlaps of the HU attenuation values. Gall fluid and pus are the only distinguishable substances. For the ρZ projected image data, we find blood, pus and the blood + pus mixtures to be clearly distinguishable in the two-dimensional ρZ plane. Gall fluid shows a small overlap to pus. The density and the atomic number values have standard deviations in the order of Δρ = 10 mg/cm
³
and ΔZ = 0.1. The theoretical density and atomic number values for blood and water are reproduced with very small deviations in the range of Δρ = -20 mg/cm
³
and ΔZ = 0.02.